Airworthiness Directives; Air Tractor, Inc. Models AT-501, AT-502, AT-502A, AT-502B, and AT-503A Airplanes, 45457-45467 [E6-12945]

Download as PDF Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL–401, Washington, DC, or on the Internet at https://dms.dot.gov. The docket number is Docket No. FAA–2006–25261; Directorate Identifier 2006–CE–38–AD. Issued in Kansas City, Missouri, on August 3, 2006. John Colomy, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. E6–12946 Filed 8–8–06; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2004–19961; Directorate Identifier 2004–CE–48–AD] RIN 2120–AA64 Airworthiness Directives; Air Tractor, Inc. Models AT–501, AT–502, AT–502A, AT–502B, and AT–503A Airplanes Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of the comment period. jlentini on PROD1PC65 with PROPOSAL AGENCY: SUMMARY: The FAA proposes to revise an earlier proposed airworthiness directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor) Models AT– 502, AT–502A, AT–502B, and AT–503A airplanes, which proposes to supersede AD 2002–26–05. AD 2002–26–05 lowers the safe life for the wing lower spar caps for Models AT–502, AT–502A, AT– 502B, and AT–503A airplanes and those that incorporate or have incorporated Marburger Enterprises, Inc. (Marburger) winglets. AD 2002–26–05 also requires you to eddy-current inspect the wing lower spar caps immediately before modifying to correct any crack in a bolt hole before it extends to the modified center section of the wing and report the results of the inspection to the FAA if cracks are found. AD 2002–11–05 R1 currently requires similar action on Model AT–501 airplanes. Since issuing the earlier NPRM, we determined that Model AT–501 airplanes should be added to the Applicability section of this proposed AD and that this proposed AD should also supersede AD 2002–11– 05 R1. We have revised the alternative method of compliance (AMOC) to include inspection procedures for airplanes that have or have had Marburger winglets installed. We have also updated the safe life of the replacement and new production spar VerDate Aug<31>2005 20:41 Aug 08, 2006 Jkt 208001 cap based on additional data we have received from the manufacturer. Since these actions impose an additional burden over that proposed in the earlier NPRM, we are reopening the comment period to allow the public the chance to comment on these additional actions. DATES: We must receive any comments on this proposed AD by October 10, 2006. ADDRESSES: Use one of the following addresses to comments on this proposed AD: • DOT Docket Web site: Go to https:// dms.dot.gov and follow the instructions for sending your comments electronically. • Government-wide rulemaking Web site: Go to https://www.regulations.gov and follow the instructions for sending your comments electronically. • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL–401, Washington, DC 20590– 0001. • Fax: (202) 493–2251. • Hand Delivery: Room PL–401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service information identified in this proposed AD, contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; or Marburger Enterprises, Inc., 1227 Hillcourt, Williston, North Dakota 58801; telephone: (800) 893– 1420 or (701) 774–0230; facsimile: (701) 572–2602. FOR FURTHER INFORMATION CONTACT: Direct all questions to: • For the airplanes that do not incorporate and never have incorporated Marburger Enterprises, Inc. winglets: Rob Romero, Aerospace Engineer, FAA, Fort Worth Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193– 0150; telephone: (817) 222–5102; facsimile: (817) 222–5960; e-mail: robert.a.romero@faa.gov; and • For airplanes that incorporate or have incorporated Marburger Enterprises, Inc. winglets: John Cecil, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, 3960 Paramount Boulevard, Lakewood, California 90712; telephone: (562) 627– 5228; facsimile: (562) 627–5210. SUPPLEMENTARY INFORMATION: Comments Invited We invite you to send any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include the docket PO 00000 Frm 00021 Fmt 4702 Sfmt 4702 45457 number, ‘‘FAA–2004–19961; Directorate Identifier 2004–CE–48–AD’’ at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD in light of those comments. We will post all comments we receive, without change, to https:// dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive concerning this proposed AD. Discussion Prior to issuing this supplemental notice of proposed rulemaking (NPRM), we issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Air Tractor Models AT–502, AT–502A, AT–502B, and AT–503A airplanes. That proposal was published in the Federal Register as an NPRM on February 9, 2005 (70 FR 6786). The NPRM proposed to supersede AD 2002–26–05 with a new AD that would retain the actions required in AD 2002–26–05, add additional airplanes to the applicability, and incorporate an AMOC to the actions retained from AD 2002–26–05. AD 2002–26–05, Amendment 39– 12991 (68 FR 18, January 2, 2003), currently applies to certain Air Tractor Models AT–502, AT–502A, AT–502B, and AT–503A airplanes. AD 2002–26– 05 supersedes AD 2002–11–03 and requires the following: • Maintaining the original requirements from AD 2002–11–03 for a lowered safe life, inspection, replacement/modification, and if cracks are found, reporting the results to the FAA; • Further lowering the safe life for the wing lower spar cap established in AD 2002–11–03 for Models AT–502, AT– 502B, and AT–503A airplanes; and • Expanding the applicability of Models AT–502A and AT–502B airplanes to account for future manufactured airplanes. With this supplemental NPRM we are also proposing to supersede AD 2002– 11–05 R1, Amendment 39–14564 (71 FR 19629, April 17, 2006), which currently applies to certain Air Tractor Model AT–501 airplanes. We issued AD 2002– 11–05 R1 to revise AD 2002–11–05 to remove AT–400 series and Models AT– 802 and AT–802A airplanes from the applicability because separate AD actions were issued for those airplanes. E:\FR\FM\09AUP1.SGM 09AUP1 45458 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules AD 2002–11–05 R1 retains the actions required in AD 2002–11–05 for Model AT–501 airplanes. The following is a list of ADs that have been issued to date that are related AD No. 2000–14–51 2001–10–04 2001–10–04 2002–11–05 ..................... ..................... R1 ................ ..................... 2002–13–02 2002–11–03 2002–26–05 2003–06–01 2002–11–05 2006–08–08 2006–08–09 ..................... ..................... ..................... ..................... R1 ................ ..................... ..................... Affected air tractor model airplanes Comments We provided the public the opportunity to participate in developing the proposed AD on Air Tractor Models AT–502, AT–502A, AT–502B, and AT– 503A airplanes. The following presents the comments received on this earlier proposed AD and FAA’s response to each comment: jlentini on PROD1PC65 with PROPOSAL Status AT–501, AT–502, and AT–502A .......................................................................... AT–400, AT–500, and AT–800 Series ................................................................. AT–400, AT–500, and AT–800 Series ................................................................. AT–400, AT–401, AT–401B, AT–402, AT–402A, AT–402B, AT–501, AT–802, and AT–802A. AT–300, AT–301, AT–302, AT–400, and AT–400A Airplanes ............................ AT–502, AT–502A, AT–502B, and AT–503A ...................................................... AT–502, AT–502A, AT–502B, and AT–503A ...................................................... AT–300, AT–301, AT–302, AT–400, and AT–400A ............................................ AT–501 ................................................................................................................. AT–400, AT–401, AT–401B, AT–402, AT–402A, and AT–402B ........................ AT–802 and AT–802A ......................................................................................... You may view these ADs at the following Internet Web site addresses: https://www.airweb.faa.gov/ Regulatory_and_Guidance_Library/ rgAD.nsf/MainFrame?OpenFrameSet or https://www.gpoaccess.gov/fr/ index.html. Comment Issue No. 1: Allow Repetitive Inspection and an Upper Life Limit on the New Cap Lewis Air Service states there is a need to incorporate an alternative solution that includes repetitive inspections and an upper life limit on the new cap. Based on the way the NPRM is currently written, the commenter believes the low cap replacement time is too burdensome and not cost effective. Although we agree that repetitive inspections may reduce the economic impact and minimize the risk of reduced agricultural production, this will not meet the safety intent of this proposed AD. We determined that reliance on critical repetitive inspections carries an unnecessary safety risk when parts replacement or modifications exist. In determining what inspections are critical, the FAA considers (1) the safety consequences of the airplane if the known problem is not detected by the inspection; (2) the reliability of the inspection, such as the probability of not detecting the known problem; (3) whether the inspection area is difficult to access; and (4) the possibility of damage to an adjacent structure as a result of the problem. VerDate Aug<31>2005 to the wing spar inspection and safe life on Air Tractor airplanes: 18:06 Aug 08, 2006 Jkt 208001 Since the initial publication of the earlier proposed AD, Air Tractor has completed fatigue testing on the replacement spar cap. The life of the cap has been updated in this proposed AD to reflect the results of this testing and subsequent analysis. We are not changing this proposed AD based on this comment but are changing it based on new data from the manufacturer. Comment Issue No. 2: Proposed AD Is Not Necessary M&M Air Service states that they operate eight different Air Tractor airplanes and to date have not found any cracks. The commenter indicates that the proposed rulemaking is confusing, not cost beneficial, and excessive. Based on these comments, we infer that the commenter wants the NPRM withdrawn. We do not agree with the commenter. Fatigue analysis/testing/fleet history shows that the wing spar will crack and fail over time. The commenter’s airplanes not cracking to date does not prevent the unsafe condition from developing on the commenter’s airplanes or other airplanes of the same type design in the future. To date, we have received over 50 reports of cracked spar caps on AT–502 series airplanes and one report of complete wing separation. We realize that there are many different wing configurations in-service on these airplanes and each has different requirements. However, analysis shows that the airplane could fail in the affected area based on the design and normal utilization of the type design airplanes. We are not changing this proposed AD based on this comment. PO 00000 Frm 00022 Fmt 4702 Sfmt 4702 Superseded by AD 2001–10–04. Revised by AD 2001–10–04 R1. Superseded by AD 2002–11–05. Revised by AD 2002–11–05 R1. Superseded by AD 2003–06–01. Superseded by AD 2002–26–05. Current. Current. Current. Current. Current. Comment Issue No. 3: Compliance Time To Accommodate Flying Schedules The National Agricultural Aviation Association requests the FAA consider the flying schedules of the airplanes and accommodate a program that can be done during the off-season. The commenter suggests the FAA allow repetitive inspections until an ultimate solution is reached, assuming no cracks are found. We have considered the importance of the financial and operational impact this proposed rulemaking may have on owners and operators and, in this specific case, aerial application businesses. This proposed AD uses inspections to manage the safety of the wing centerline joint instead of reducing the compliance times for replacing parts. However, this approach cannot be used indefinitely. Extending the service life of fatigue-critical, primary structure areas requires not only ensuring the safety of the area being inspected or modified, but also ensuring the safety of the complete structure when extending the service life. Fatigue analysis shows that the safe life is the solution to the unsafe condition, not repetitive inspections over the life of the airplane. For eligible airplanes, we are providing an AMOC that provides an aggressive repetitive inspection program until 8,000 hours time-in-service (TIS), provided no cracks are found. The FAA has shown a history of accommodating flying schedules through AMOCs on previous ADs for this subject. We will continue to consider AMOCs provided they maintain a level of safety acceptable to the FAA. For the replacement spar cap, we have received new data that justifies a much higher safe life than was previously published in the NPRM. E:\FR\FM\09AUP1.SGM 09AUP1 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules We are not changing this proposed AD based on this comment. jlentini on PROD1PC65 with PROPOSAL Comment Issue No. 4: Lack of Wing LifeLimit Information Julie Broussard of Lewis Flying and Maintenance Service, Inc., states that she was never informed in writing of a 1,600 hour safe life or replacement life of 8,000 hours TIS for the AT–502 wing. The commenter also urges the FAA to make the manufacturer ‘‘fix the wing.’’ We issued AD 2002–26–05, Amendment 39–12991 (68 FR 18, January 2, 2003), which applies to Air Tractor Models AT–502, AT–502A, AT– 502B, and AT–503A airplanes. That AD lowers the safe life for the wing lower spar caps to 1,650 hours TIS. AD 2002– 26–05 supersedes AD 2002–11–03, Amendment 39–12764 (67 FR 38371, June 4, 2002). We also issued Special Airworthiness Information Bulletin (SAIB) CE–05–28, dated January 21, 2005, announcing an AMOC to AD 2002–26–05. The AMOC allows an inspection program instead of the safe life replacement program required by AD 2002–26–05, which allows operation of a modified wing up to 8,000 hours TIS, provided no cracks are found during required inspections. We are legally bound to notify the public of an AD through publication in the Federal Register. AD 2002–26–05 was published in the Federal Register on January 2, 2003. In the past, we have sent copies of ADs and SAIBs to registered owners of the affected airplanes, which could be a bank or holding company. This may be the reason the commenter did not receive notification of the change in the safe life limit and replacement schedule. This supplemental NPRM is still only a proposal at this time. The previous NPRM on this subject was published in the Federal Register on February 9, 2005 (70 FR 6786). We will always encourage modifications that incorporate design changes that make critical parts stronger and safer. However, our responsibility is to address the continued operational safety of the airplane fleet, ensure that current design regulations are met, and correct any unsafe conditions. Establishing a safe life and an option of an aggressive repetitive inspection schedule until 8,000 hours TIS (provided no cracks are found) meets the FAA’s responsibility. Further, the replacement spar cap has been substantiated to a much higher safe life than previously published. We are not changing this proposed AD based on this comment. VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 Comment Issue No. 5: New Production Airplanes Have a 27 Percent Increase in Safe Life The National Transportation Safety Board (NTSB) questions the rationale for new production AT–502B airplanes having a 27 percent increase in the safe life limit on the wing from 1,650 hours TIS to 2,100 hours TIS. The commenter also states a concern for the conservatism in the initial and repetitive inspection program. Other items of concern to the commenter are: • The wording proposed in section (e)(2) of the earlier proposed AD may allow for inspections to continue indefinitely. The commenter states that airplanes using the AMOC who find cracks should report them to the FAA. • Airplanes that have been modified with a replacement cap should follow the inspection program for later serial number airplanes. • There has been nothing done to address the use of winglets as it applies to inspection intervals. The safe life for new production AT– 502B airplanes was determined as a result of fatigue testing performed by the manufacturer. The initial and repetitive inspection program was based on a thorough damage tolerance analysis using a validated load spectrum and coupon testing. It should be noted that since publication of the earlier NPRM, the manufacturer has completed more extensive testing, and we are now proposing a safe life for new production AT–502B airplanes that represents much more than the 27 percent increase the commenter states. We do not agree that paragraph (e)(2) of the previously proposed AD allowed for indefinite inspections. Paragraph (e)(2) of the proposed AD refers to Appendix 2, which has clearly defined upper limits on inspection times (8,000 hours TIS for eligible airplanes). We agree that any cracks detected should be reported to the FAA. We are retaining the reporting requirement from the earlier NPRM in this proposed AD. Airplanes with replacement spar caps, as well as new production airplanes, are no longer required to follow an inspection program. We agree that we did not address an inspection program for airplanes with winglets installed. We are revising this proposed AD to include an AMOC inspection program for airplanes that have or have had winglets installed. Further, this proposed AD states that airplanes with the new or replacement spar caps are not eligible to have the winglet STC installed without proper fatigue substantiation. PO 00000 Frm 00023 Fmt 4702 Sfmt 4702 45459 Comment Issue No. 6: Include Model AT–501 Airplanes in the Applicability Leland Snow, President of Air Tractor, Inc., states that Model AT–501 airplanes should be included in the Applicability section and that new airplanes should not have a safe life limit of 3,100 hours TIS. The commenter states the costs for doing the inspection is too low. The inspection typically costs from $450 to $550. Parts cost for the replacement spar cap is approximately $16,500 plus approximately $16,500 for labor (a total of $33,000). The commenter also states that winglets should be removed before allowing the AMOC. We agree with the commenter that Model AT–501 airplanes should be included in the Applicability section. We also agree to update the Cost Impact section. We are revising this proposed AD to include those changes. We do not agree that airplanes with winglets installed should be excluded from the AMOC. We are adding an AMOC inspection program in this proposed AD to cover airplanes that have winglets installed following Supplemental Type Certificate (STC) SA00490LA. Comment Issue No. 7: Torsion Loads John R. Janssen states that torsion loads need to be accounted for to properly address the wing safe life limit for the affected airplanes. We agree with the commenter that the torsion load is a contributing factor to the fatigue life of the wings, as are all the other loads (ground, gust, maneuver, etc.). These loads have been accounted for in the load spectrum that was used in developing the inspection program and the life of the new/replacement spar cap. We are not changing this proposed AD based on this comment. Comment Issue No. 8: Marburger Winglets Lewis Broussard, Owner, Lewis Flying and Maintenance Service, Inc., states that installing Marburger Enterprise, Inc. winglets increases the safe life of the wing. We do not agree with the commenter. We have data that shows adding winglets increases the operating stresses at the wing root and consequently leads to a reduced safe life. We are not changing this proposed AD based on this comment. Comment Issue No. 9: AMOC Should Apply to Airplanes With Winglets Rick Marburger of Marburger Enterprises, Inc., states that airplanes E:\FR\FM\09AUP1.SGM 09AUP1 45460 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules with winglets installed should be included in the AMOC repetitive inspection program. We agree with the commenter. We included procedures in the AMOC repetitive inspection program to address airplanes that have or have had winglets installed. We are revising this proposed AD to incorporate this change. Comment Issue No. 10: Unfair Safe Life Limit for the New Spar Cap Tom Miller of Ingalls Aerial Sprayers, Inc., states the safe life limit of 3,100 hours TIS for the new/replacement spar cap is unfair. Numerous other commenters have similar concerns. The commenters state the new design should be given a safe life limit that is equivalent to the old design, which is 8,000 hours TIS. We agree with the commenters. The 3,100-hour TIS safe life limit was based on data submitted by Air Tractor and approved by the FAA. However, since the earlier proposed AD was published, Air Tractor began a new test program using a recently validated load spectrum to determine a new safe life for this design configuration. That testing has been completed and the new safe life limit is being published in this proposed AD. We are revising this proposed AD to incorporate this change. Relevant Service Information The following service information from AD 2002–11–05 R1 and the previous NPRM are still valid for this supplemental NPRM: • Snow Engineering Drawing Number 21050; • Snow Engineering Service Letters #197 or #205, both revised March 26, 2001; and • Snow Engineering Service Letter #244, dated April 25, 2005. Snow Engineering Co. has a licensing agreement with Air Tractor that allows them to produce technical data for use on Air Tractor products. FAA’s Determination and Requirements of This Proposed AD Since issuing the earlier NPRM, we determined that Model AT–501 airplanes should be added to the Applicability section. We also developed an AMOC to the requirements of AD 2002–26–05 for airplanes that have or have had winglets installed. We are extending the safe life for new production airplanes and replacement spar caps. After examining the circumstances and reviewing all available information related to the incidents described above, we have determined that: • The unsafe condition referenced in this document exists or could develop on other Air Tractor Models AT–501, AT–502, AT–502A, AT–502B, and AT– 503A airplanes of the same type design that are on the U.S. registry; • We should change this proposed AD to include Model AT–501 airplanes in the Applicability section and revise the AMOC. • We should take AD action to correct this unsafe condition. The Supplemental NPRM Adding additional models to the Applicability section goes beyond the scope of what was originally proposed in the earlier NPRM. Therefore, we are reopening the comment period and allowing the public the chance to comment. This proposed AD would supersede AD 2002–26–05 and AD 2002–11–05 R1 with a new AD that would: • Retain the actions required in AD 2002–26–05 and AD 2002–11–05 R1; • Add additional airplanes to the Applicability section; • Incorporate a revised AMOC to include inspection procedures for airplanes that have or have had winglets installed following STC SA00490LA; and • Extend the safe life for new production airplanes and replacement spar caps. The following table summarizes the effects this proposed AD would have on the airplane models affected by this proposed AD: Model AT–501 ................................. AT–502 ................................. AT–502A .............................. AT–502B .............................. • • • • • • • • • • • • • • AT–503A .............................. • • • Supersede AD 2002–11–05 R1. Retain the safe lives from AD 2002–11–05 R1. Provide an AMOC that allows extension of the safe life through an inspection and modification program. Supersede AD 2002–26–05. Retain the safe lives from AD 2002–26–05 and add S/Ns to applicability. AD 2002–26–05 provided safe lives for S/Ns 0003 through 0236. Proposed action applies the same safe life to all S/Ns beginning with 0003. Provide an AMOC that allows extension of the safe life through an inspection and modification program. Supersede AD 2002–26–05. Retain the safe lives from AD 2002–26–05. Provide an AMOC that allows extension of the safe life through an inspection and modification program. Supersede AD 2002–26–05. Retain the safe lives from AD 2002–26–05 for S/Ns 0187 through 0654, except 0643. Increase the safe lives beyond those listed in AD 2002–26–05 for S/Ns 0655 and greater, as well as S/N 0643. Add requirement to cold work outboard wing center splice block bolt holes in the lower spar cap on S/Ns 0643 and 0655 through 0692. Provide an AMOC that allows extension of the safe life through an inspection and modification program for S/Ns 187 through 654, except 643. Supersede AD 2002–26–05. Retain the safe lives from AD 2002–26–05. Provide an AMOC that allows extension of the safe life through an inspection and modification program. jlentini on PROD1PC65 with PROPOSAL Costs of Compliance We estimate that this proposed AD affects approximately 500 airplanes in the U.S. registry. VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 We estimate the following costs to do each proposed inspection: PO 00000 Frm 00024 Fmt 4702 Sfmt 4702 E:\FR\FM\09AUP1.SGM 09AUP1 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules Total cost per airplane Labor cost Parts cost 8 work-hours × $80 per hour = $640 ................. No parts required for inspection ........................ 45461 Total cost on U.S. operators $640 $640 × 500 = $320,000. We estimate the following costs to do the proposed modification: Labor cost Parts cost Total cost per airplane 120 work-hours × $80 per hour = $9,600. Approximately $3,700 .......... Total cost on U.S. operators $13,300 × 500 = $6,650,000.00. $9,600 + $3,700 = $13,300 We estimate the following costs to do the proposed replacement: Labor cost Parts cost Total cost per airplane 254 work-hours × $80 per hour = $20,320 .. Approximately $16,500 .............. $20,320 + $16,500 = $36,820 Authority for This Rulemaking Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency’s authority. We are issuing this rulemaking under the authority described in subtitle VII, part A, subpart III, section 44701, ‘‘General requirements.’’ Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. jlentini on PROD1PC65 with PROPOSAL Regulatory Findings We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. For the reasons discussed above, I certify that the proposed regulation: 1. Is not a ‘‘significant regulatory action’’ under Executive Order 12866; VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 2. Is not a ‘‘significant rule’’ under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and 3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. Examining This Proposed AD Docket You may examine the AD docket that contains the proposed AD, the regulatory evaluation, any comments received, and other information on the Internet at https://dms.dot.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647–5227) is located at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, under the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 as follows: PART 39—AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: PO 00000 Frm 00025 Fmt 4702 Sfmt 4702 Total cost on U.S. operators $36,820 × 500 = $18,410,000.00. Authority: 49 U.S.C. 106(g), 40113, 44701. § 39.13 [Amended] 2. FAA amends § 39.13 by removing Airworthiness Directive (AD) 2002–26– 05, Amendment 39–12991 (68 FR 18, January 2, 2003) and AD 2002–11–05 R1, Amendment 39–14564 (71 FR 19628, April 17, 2006), and by adding a new AD to read as follows: Air Tractor, Inc.: Docket No. FAA–2004– 19961; Directorate Identifier 2004–CE– 48–AD. Comment Due Date (a) We must receive comments on this proposed airworthiness directive (AD) by October 10, 2006. Affected AD (b) This AD supersedes AD 2002–26–05, Amendment 39–12991, and AD 2002–11–05 R1, Amendment 39–14564. Applicability (c) This AD applies to certain Models AT– 501, AT–502, AT–502A, AT–502B, and AT– 503A airplanes. Use Table 1 in paragraph (c)(1) of this AD for airplanes that do not incorporate and never have incorporated Marburger Enterprises, Inc. (Marburger) winglets. Use Table 2 in paragraph (c)(4) of this AD for certain AT–500 series airplanes that incorporate or have incorporated Marburger winglets. (1) The following table applies to airplanes (certificated in any category) that do not incorporate and never have incorporated Marburger winglets along with the safe life (presented in hours time-in-service (TIS)) of the wing lower spar cap for all affected airplane models and serial numbers: E:\FR\FM\09AUP1.SGM 09AUP1 45462 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules TABLE 1.—SAFE LIFE FOR AIRPLANES THAT DO NOT INCORPORATE AND NEVER HAVE INCORPORATED MARBURGER WINGLETS Wing lower spar cap safe life Model Serial Nos. AT–501 .................................... AT–501 .................................... AT–502 .................................... AT–502A ................................. AT–502B ................................. AT–502B ................................. AT–502B ................................. AT–502B ................................. AT–503A ................................. 0002 through 0061 ................................................................................................................ All serial numbers beginning with 0062 ................................................................................ All serial numbers beginning with 0003 ................................................................................ All serial numbers beginning with 0158 ................................................................................ 0187 through 0654, except 0643 .......................................................................................... 0643, and 0655 through 0692 ............................................................................................... 0693 through 0701 ................................................................................................................ All serial numbers beginning with 0702 ................................................................................ All serial numbers beginning with 0067 ................................................................................ (2) If piston-powered airplanes have been converted to turbine power, you must use the limits for the corresponding serial number (S/N) turbine-powered airplanes. (3) Airplanes that have been modified to install lower spar caps, part numbers (P/N) 21058–1 and 21058–2, should use a safe life of 9,800 hours TIS. (4) The following table applies to airplanes (certificated in any category) that incorporate or have incorporated Marburger winglets. These winglets are installed following Supplemental Type Certificate (STC) 4,531 7,693 1,650 1,650 1,650 9,000 9,500 9,800 1,650 hours hours hours hours hours hours hours hours hours TIS. TIS. TIS. TIS. TIS. TIS. TIS. TIS. TIS. SA00490LA. Use the winglet usage factor in Table 2 of this paragraph, the safe life specified in Table 1 in paragraph (c)(1) of this AD, and the instructions included in Appendix 1 to this AD to determine the new safe life of airplanes that incorporate or have incorporated Marburger winglets: TABLE 2.—WINGLET USAGE FACTOR TO DETERMINE THE SAFE LIFE FOR AIRPLANES THAT INCORPORATE OR HAVE INCORPORATED MARBURGER WINGLETS INSTALLED FOLLOWING STC SA00490LA Winglet usage factor Model Serial Nos. AT–501 ..................................... AT–501 ..................................... AT–502 ..................................... AT–502A ................................... AT–502A ................................... AT–502B ................................... 0002 through 0061 ....................................................................................................................... All serial numbers beginning with 0062 ....................................................................................... 0003 through 0236 ....................................................................................................................... 0158 through 0238 ....................................................................................................................... All serial numbers beginning with 0239 ....................................................................................... All serial numbers beginning with 0187 ....................................................................................... (5) Model AT–502B airplanes, S/N 0643, all S/Ns beginning with 0655, and all other airplanes that have been modified with replacement spar caps, P/N 21058–1 and P/ N 21058–2, are not eligible to have STC SA00490LA installed without additional fatigue data being provided to the FAA at the address in paragraph (f) of this AD. Unsafe Condition (d) This AD is the result of service reports and analysis done on wing lower spar caps of Air Tractor, Inc. airplanes. The actions specified by this AD are intended to prevent fatigue cracks from occurring in the wing lower spar cap before the established safe life is reached. Fatigue cracks in the wing lower 1.6 1.6 1.6 1.6 1.2 1.2 spar cap, if not detected and corrected, could result in failure of the spar cap and lead to wing separation and loss of control of the airplane. Compliance (e) To address this problem, you must do the following: jlentini on PROD1PC65 with PROPOSAL Actions Compliance Procedures (1) For all affected airplanes: Modify the applicable airplane records (logbook) as follows to show the reduced safe life for the wing lower spar cap (use the information from Table 1 in paragraph (c)(1), Table 2 in paragraph (c)(4), and Appendix 1 of this AD, as applicable): (i) Incorporate the following into the airplane logbook ‘‘In accordance with AD **–**–** (AD 2002–26–05 or AD 2002–11–05, as applicable) the wing lower spar cap is life limited to ll.’’ Insert the applicable safe life number from the applicable tables in paragraphs (c)(1) and (c)(4) of this AD and Appendix 1 of this AD. (ii) If, as of the time of the logbook entry requirement of paragraph (e)(1)(i) of this AD, your airplane is over or within 50 hours of the safe life, an additional 50 hours TIS after the effective date of this AD is allowed to do the replacement. For airplanes previously affected by AD 2002–26–05: Do the logbook entry within the next 10 hours TIS after January 15, 2003 (the effective date of AD 2002–26– 05). For airplanes not previously affected by AD 2002–26–05: Do the logbook entry within the next 10 hours TIS after the effective date of this AD, unless already done. The logbook language for AT–501 airplanes is referenced as AD 2002–11–05 instead of AD 2002–11–05 R1 to maintain continuity and assures no further action is necessary. Airplane Records Modification: The owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7) may modify the airplane records as specified in paragraph (e)(1) of this AD. Make an entry into the airplane records showing compliance with this portion of the AD in accordance with section 43.9 of the Federal Aviation Regulations (14 CFR 43.9). Spar Cap Replacement: Do the replacement when the safe life is reached following Snow Engineering Drawing Number 21050, Snow Engineering Service Letters #197 or #205, both revised March 26, 2001, as applicable. The owner/operator may not do the spar cap modification/replacement, unless he/she holds the proper mechanic authorization. VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 PO 00000 Frm 00026 Fmt 4702 Sfmt 4702 E:\FR\FM\09AUP1.SGM 09AUP1 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules 45463 Actions Compliance Procedures (2) For all affected airplanes: To extend the safe life of the wing lower spar cap, you may eddy-current inspect and modify the wing lower spar cap. The inspection schedule and modification procedures are included in Appendix 2 to this AD. (3) For all affected airplanes: Report to the FAA any cracks detected as the result of each inspection required by paragraph (e)(2) of this AD on the form in Figure 1 of this AD. The Office of Management and Budget (OMB) approved the information collection requirements contained in this regulation under the provisions of the Paperwork Reduction Act and assigned OMB Control Number 2120– 0056. (4) For Model AT–502B airplanes, S/Ns 502B– 0643, and 502B–0655 through 502B–0692: Cold work the left-hand and right-hand two outboard wing center splice block bolt holes (4 total) in the lower spar cap. (5) For all affected airplanes: Airplanes that have the two-part modification done following the applicable service bulletins (Snow Engineering Service Letters #197 or #205, both revised March 26, 2001; or Snow Engineering Service Letter #244, dated April 25, 2005), but have over-sized outboard bolt holes at the splice block, must obtain an AMOC from FAA as specified in paragraph (f) of this AD to determine applicable inspection intervals. Inspection schedule included as part of the alternative method of compliance (AMOC) in Appendix 2 to this AD. Procedures included as part of the AMOC in Appendix 2 to this AD. Only if cracks are found, send the report within 10 days after the inspection required in paragraph (e)(2) of this AD. Send the form (Figure 1 of this AD) to FAA, Fort Worth Airplane Certification Office, Attn: Rob Romero, 2601 Meacham Boulevard, Fort Worth, Texas 76193–0150; telephone: (817) 222–5102; facsimile: (817) 222–5960. Before accumulating 2,000 hours TIS or within the next 100 hours TIS after the effective date of this AD, whichever occurs later. Following Snow Engineering Service Letter #244, dated April 25, 2005. Not applicable. ................................................. Not applicable. jlentini on PROD1PC65 with PROPOSAL BILLING CODE 4910–13–P VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 PO 00000 Frm 00027 Fmt 4702 Sfmt 4702 E:\FR\FM\09AUP1.SGM 09AUP1 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules jlentini on PROD1PC65 with PROPOSAL BILLING CODE 4910–13–C Alternative Methods of Compliance (AMOC) (f) The Manager, Fort Worth or Los Angeles Airplane Certification Office (ACO), as applicable (see paragraphs (f)(1)(i) and (f)(2)(ii) of this AD below for specific contacts), has the authority to approve VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. (1) For information on any already approved AMOCs, contact: (i) For the airplanes that do not incorporate and never have incorporated Marburger Enterprises, Inc. winglets: Rob Romero, Aerospace Engineer, FAA, Fort Worth PO 00000 Frm 00028 Fmt 4702 Sfmt 4702 Airplane Certification Office, 2601 Meacham Boulevard, Fort Worth, Texas 76193–0150; telephone: (817) 222–5102; facsimile: (817) 222–5960; e-mail: robert.a.romero@faa.gov. (ii) For airplanes that incorporate or have incorporated Marburger Enterprises, Inc. winglets: John Cecil, Aerospace Engineer, Los Angeles Aircraft Certification Office, FAA, E:\FR\FM\09AUP1.SGM 09AUP1 EP09AU06.007</GPH> 45464 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules 3960 Paramount Boulevard, Lakewood, California 90712; telephone: (562) 627–5228; facsimile: (562) 627–5210. (2) AMOCs approved for AD 2001–10–04 and/or AD 2000–14–51 are not considered approved for this AD. (3) AMOCs approved for AD 2001–10–04 R1, AD 2002–11–03, AD 2002–11–05, AD 2002–11–05 R1, or AD 2002–26–05 are considered approved for this AD. Special Flight Permit (g) Under 14 CFR part 39.23, we are limiting the special flight permits for this AD by the following conditions: (1) Operate only in day visual flight rules (VFR). (2) Ensure that the hopper is empty. (3) Limit airspeed to 135 miles per hour (mph) indicated airspeed (IAS). (4) Avoid any unnecessary g-forces. (5) Avoid areas of turbulence. (6) Plan the flight to follow the most direct route. jlentini on PROD1PC65 with PROPOSAL Related Information (h) To get copies of the documents referenced in this AD, contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; or Marburger Enterprises, Inc., 1227 Hillcourt, Williston, North Dakota 58801. To view the AD docket, go to the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL–401, Washington, DC, or on the Internet at https://dms.dot.gov. The docket number is FAA–2004–19961. Appendix 1 to Docket No. FAA–2004–19961 The following provides procedures for determining the safe life for those Models AT–501, AT–502, AT–502A, and AT–502B airplanes that incorporate or have incorporated Marburger Enterprises, Inc. (Marburger) winglets. These winglets are installed in accordance with Supplemental Type Certificate (STC) No. SA00490LA. If you have removed the Marburger winglets before further flight after the effective date of this AD or before the effective date of this AD, do the following: 1. Review your airplane’s logbook to determine your airplane’s time-in-service (TIS) with winglets installed per Marburger STC No. SA00490LA. This includes all time spent with the winglets currently installed and any previous installations where the winglet was installed and later removed. Example: A review of your airplane’s logbook shows that you have accumulated 350 hours TIS since incorporating the Marburger STC. Further review of the airplane’s logbook shows that a previous owner had installed the STC and later removed the winglets after accumulating 150 hours TIS. Therefore, your airplane’s TIS with the winglets installed is 500 hours. If you determine that the winglet STC has never been incorporated on your airplane, then your safe life is presented in Table 1 in paragraph (c)(1) of this AD. Any future winglet installation will be subject to a reduced safe life per these instructions. 2. Determine your airplane’s unmodified safe life from Table 1 in paragraph (c)(1) of this AD. VerDate Aug<31>2005 20:41 Aug 08, 2006 Jkt 208001 Example: Your airplane is a Model AT–502B, serial number (S/N) 0292. From Table 1 in paragraph (c)(1) of this AD, the unmodified safe-life of your airplane is 1,650 hours TIS. All examples from hereon will be based on the Model AT–502B, S/N 0292 airplane. 3. Determine the winglet usage factor from Table 2 in paragraph (c)(4) of this AD. Example: Again, your airplane is a Model AT–502B, S/N 0292. From Table 2 in paragraph (c)(4) of this AD, your winglet usage factor is 1.2. 4. Adjust the winglet TIS to account for the winglet usage factor. Multiply the winglet TIS (result of Step 1 above) by the winglet usage factor (result of Step 3 above). Example: Winglet TIS is 500 hours × a winglet usage factor of 1.2. The adjusted winglet TIS is 600 hours. 5. Calculate the winglet usage penalty. Subtract the winglet TIS (result of Step 1 above) from the adjusted winglet TIS (result of Step 4 above). Example: Adjusted winglet TIS ¥ the winglet TIS = Winglet usage penalty. (600 hours TIS) ¥ (500 hours TIS) = (100 hours TIS). 6. Adjust the safe life of your airplane to account for winglet usage. Subtract the winglet usage penalty (result of Step 5 above) result from the unmodified safe life from Table 1 in paragraph (c)(1) of this AD (the result of Step 2 above). Example: Unmodified safe life ¥ winglet usage penalty = Adjusted safe life. (1,650 hours TIS) ¥ (100 hours TIS) = (1,550 hours TIS). 7. If you remove the winglets from your airplane before further flight or no longer have the winglets installed on your airplane, the safe life of your airplane is the adjusted safe life (result of Step 6 above). Enter this number in paragraph (e)(1)(i) of this AD and the airplane logbook. If you have the Marburger winglets installed as of the effective date of this AD and plan to operate your airplane without removing the winglets, do the following: 1. Review your airplane’s logbook to determine your airplane’s TIS without the winglets installed. Example: A review of your airplane’s logbook shows that you have accumulated 1,500 hours TIS, including 500 hours with the Marburger winglets installed. Therefore, your airplane’s TIS without the winglets installed is 1,000 hours. 2. Determine your airplane’s unmodified safe life from Table 1 in paragraph (c)(1) of this AD. Example: Your airplane is a Model AT–502B, S/N 0292. From Table 1 in paragraph (c)(1) of this AD, the unmodified safe life of your airplane is 1,650 hours TIS. All examples from hereon will be based on the Model AT–502B, S/N 0292 airplane. 3. Determine the winglet usage factor from Table 2 in paragraph (c)(4) of this AD. Example: Again, your airplane is a Model AT–502B, S/N 0292. From Table 2 in PO 00000 Frm 00029 Fmt 4702 Sfmt 4702 45465 paragraph (c)(4) of this AD, your winglet usage factor is 1.2. 4. Determine the potential winglet TIS. Subtract the TIS without the winglets installed (result of Step 1 above) from the unmodified safe life (result of Step 2 above). Example: Unmodified safe life ¥ TIS without winglets = Potential winglet TIS. (1,650 hours TIS) ¥ (1,000 hours TIS) = (650 hours TIS). 5. Adjust the potential winglet TIS to account for the winglet usage factor. Divide the potential winglet TIS (result of Step 4 above) by the winglet usage factor (result of Step 3 above). Example: Potential winglet TIS ÷ winglet usage factor = Adjusted potential winglet TIS. (650 hours TIS) ÷ (1.2) = (541 hours TIS). 6. Calculate the winglet usage penalty. Subtract the adjusted potential winglet TIS (result of Step 5 above) from the potential winglet TIS (result of Step 4 above). Example: Potential winglet TIS ¥ adjusted potential winglet TIS = Winglet usage penalty. (650 hours TIS) ¥ (541 hours TIS) = (109 hours TIS). 7. Adjust the safe life of your airplane to account for the winglet installation. Subtract the winglet usage penalty (result of Step 6 above) from the unmodified safe life from Table 1 in paragraph (c)(1) of this AD (the result of Step 2 above). Example: Unmodified safe life ¥ winglet usage penalty = Adjusted safe life. (1,650 hours TIS) ¥ (109 hours TIS) = (1,541 hours TIS). 8. Enter the adjusted safe life (result of Step 7 above) in paragraph (e)(1)(i) of this AD and the airplane logbook. If you install or remove the Marburger winglets from your airplane in the future, do the following: If, at anytime in the future, you install or remove the Marburger winglets STC from your airplane, you must repeat the procedures in this Appendix to determine the airplane’s safe life. APPENDIX 2—ALTERNATIVE METHOD OF COMPLIANCE (AMOC) TO DOCKET NO. FAA–2004–19961 Optional Inspection Program For all airplanes listed in this AD; except for Model AT–502B airplanes, serial number (S/N) 0643 and all S/Ns beginning with 0655, and those airplanes that have been modified with the replacement spar caps, part number (P/N) 21058–1 and P/N 21058–2; you may begin a repetitive inspection interval program as an alternative to the safe life requirement of this AD with the following provisions: For the Model AT–501 airplanes affected by this AD, you may elect to follow this AMOC program and continue to operate your airplane up to 8,000 hours TIS, provided you comply with this AMOC in its entirety. If at the time of the effective date of this AD, you are over 1,600 hours TIS (the time required for the first inspection), you must inspect within 50 hours TIS. If at the time of the E:\FR\FM\09AUP1.SGM 09AUP1 jlentini on PROD1PC65 with PROPOSAL 45466 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules effective date of this AD, you are over 4,000 hours TIS (the time required for 2-part modification), you must have the modification done within 50 hours TIS. If you choose not to follow this inspection program, then you must replace your lower spar caps and associated hardware at the applicable safe life listed in this AD following the procedures in paragraph (e). For airplanes that do not and never have had Marburger Enterprise, Inc. winglets installed following Supplemental Type Certificate (STC) SA00490LA: 1. Upon accumulating 1,600 hours time-inservice (TIS) or within the next 50 hours TIS after [effective date] (the effective date of AD **–**–**), whichever occurs later, eddycurrent inspect the outboard two lower spar cap bolt holes following Snow Engineering Process Specification #197, page 1, revised June 4, 2002; pages 2 through 5, revised May 3, 2002. The inspection must be done by one of the following: a. A Level 2 or Level 3 inspector that is certified for eddy-current inspection using the guidelines established by the American Society for Nondestructive Testing or MIL– STD–410; or b. A person authorized to do AD work and has completed and passed the Air Tractor, Inc. training course on Eddy Current Inspection on wing lower spar caps. 2. Repeat these inspections at intervals of (as applicable): a. 800 hours TIS (all S/Ns except as noted in b); or b. 600 hours TIS (S/Ns 502B–0187 through 502B–0618 that do not have P/N 20998–1/2 web plate installed). c. If the outboard two lower spar cap bolt holes have been cold worked following Snow Engineering Service Letter #233, dated May 18, 2004, then you may double (1,600 hours TIS or 1,200 hours TIS, as applicable) the inspection interval (See Step 8—re: mid cycle cold work). d. Your logbook entry must include the work done and the inspection intervals that are upcoming, as follows: Following AD **–**–**, at XXXX {insert hours TIS of the initial pre-modification inspection} hours TIS an eddy-current inspection has been performed. As of now, the safe life listed in the AD no longer applies to this airplane. This airplane must be eddy-current inspected at intervals not to exceed {800/600/1,600/1,200, as applicable} hours TIS. The first of these inspections is due at {insert the total number of hours TIS the first of these inspections is due} hours TIS.’’ 3. If at any time a crack is found, and: a. The crack indication goes away by doing the modification following the applicable sheet of Snow Engineering Modification— Wing Centersplice—502, Drawing Number 20989, then you may modify your center splice following Snow Engineering Drawing 20989. After modification, proceed to Step 5. b. The crack indication does not go away by doing the modification following the applicable sheet of Snow Engineering Modification—Wing Centersplice—502, Drawing Number 20989, you must replace all parts and hardware listed in Step 7. c. Report to the FAA any cracks found using the form in Figure 1 of this AD. VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 4. For all S/Ns, upon accumulating 4,000 hours TIS, you must: a. Modify your center splice connection following the applicable sheet of Snow Engineering Modification—Wing Centersplice—502, Drawing Number 20989, unless already done following Snow Engineering Service Letter #197 or #205, both revised March 26, 2001, as applicable. The owners/operator may not do the spar cap modification unless that person holds the proper mechanic authorization. If, as of [effective date] (the effective date of AD **– **–**), your airplane is over or within 50 hours of reaching the 4,000 hour TIS modification requirement, do the modification within the next 50 hours TIS. b. Before doing the modification, do an eddy-current inspection following Snow Engineering Process Specification #197, page 1, revised June 4, 2002; pages 2 through 5, revised May 3, 2002, unless already done following the applicable Snow Engineering Service Letter #197 or #205, both revised March 26, 2001. c. Your logbook entry must include the work done and the inspection intervals that are upcoming, as follows: ‘‘Following AD **–**–**, at XXXX {insert hours TIS of the modification} hours TIS an eddy-current inspection has been done. As of now, the safe life listed in the AD no longer applies to this airplane. This airplane must be eddy-current inspected at {insert the number of hours TIS at modification plus 1,600 hours TIS} hours TIS. 5. For all S/Ns, upon accumulating 1,600 hours TIS after modification, inspect the lefthand and right-hand outboard two lower spar cap bolt holes following Snow Engineering Process Specification #197, page 1, revised June 4, 2002; pages 2 through 5, revised May 3, 2002. 6. Repeat the inspection at intervals of: a. 800 hours TIS; or b. 1,600 hours TIS if the outboard two lower spar cap bolt holes have been cold worked following Snow Engineering Service Letter #234, dated May 18, 2004 (See Step 8). c. Your logbook entry must include the work done and the post-modification inspection intervals that are upcoming, as follows: ‘‘This airplane must be eddy-current inspected at intervals not to exceed {800/ 1,600, as applicable} hours TIS. The first of these inspections is due at {insert the total number of hours TIS the first of these inspections is due} hours TIS.’’ d. If a crack is found at any time, before further flight you must replace the lower spar caps, splice blocks, and wing attach angles and hardware. You must also notify the FAA using the form in Figure 1 of this AD. 7. Upon accumulating 8,000 hours TIS, before further flight you must replace the lower spar caps, splice blocks, and wing attach angles (P/N 20693–1), and associated hardware. No additional time will be authorized for airplanes that are at or over 8,000 hours TIS (see Step 9). 8. (OPTIONAL): If you decide to cold work your bolt holes following Snow Engineering Service Letter #233 or #234, both dated May 18, 2002, at a TIS that does not coincide with a scheduled inspection following this AD, PO 00000 Frm 00030 Fmt 4702 Sfmt 4702 then eddy-current inspect at the time of cold working and then begin the 1,600/1,200 hour TIS inspection intervals (2 times the intervals listed in Steps 2.a., 2.b., and 6.a. listed above). 9. (OPTIONAL): If you have modified your airplane in accordance with Step 4 above before accumulating 4,000 hours TIS, then you may continue to fly your airplane past (modification + 4,000 hours TIS) provided you cut your inspection intervals in half. Make a logbook entry following Step 6.c. above to reflect these reduced inspection intervals. Upon accumulating 8,000 hours TIS, you must comply with Step 7 above. EXAMPLE: An AT–502B airplane had the two-part modification installed at 3,000 hours TIS and the bolt holes have not been cold worked. The first inspection would occur at 4,600 hours TIS. From Step 5, this is modification plus 1,600 hours TIS. Inspections would follow at 5,400 hours TIS, 6,200 hours TIS, and 7,000 hours TIS. From Step 6.a. above, this is 800-hour TIS inspection intervals. Regarding the inspection at 7,000 hours TIS (modification plus 4,000 hours TIS), this relates to the 8,000-hour TIS inspection from Step 7 above, which is modification plus 4,000 hours TIS, except in this example the modification took place at 3,000 hours TIS instead of 4,000 hours TIS as specified in Step 4 above. This airplane may continue to fly if inspected again at 7,400 hours TIS and 7,800 hours TIS, which is 400-hour TIS inspection intervals. This 400-hour TIS inspection interval corresponds to Step 9 where you cut your inspection interval from Step 6.a. in half. Upon accumulating 8,000 hours TIS (this is the same as Step 7 above), you must replace the parts listed in Step 7. For airplanes that have or have had Marburger Enterprise, Inc. winglets installed following Supplemental Type Certificate (STC) SA00490LA: If you have removed the winglets, calculate new, reduced hours for Steps 1, 4, 5, and 7, as applicable, based on the winglet usage factor listed in Table 2 of paragraph (c)(4) and Appendix 2 of this AD. You may repetitively inspect at the same intervals listed in Step 2 above provided that you do not re-install the winglets. EXAMPLE: An AT–502 airplane, S/N 502– 0200, had winglets installed at 200 hours TIS and removed at 800 hours TIS. The winglet usage factor is: 1.6 Calculate equivalent hours: 600 hours TIS with winglets X 1.6 = 960 hours TIS Winglet usage penalty = 960 – 600 = 360 New Step 1 Pre-Modification Initial Inspection Time = 1,600 – 360 = 1,240 hours TIS Retained Step 2 Pre-Modification Inspection Interval: Since the winglets are removed, the Pre-Modification Inspection Interval remains 800 hours TIS. New Step 4 Modification time = 4,000 – 360 = 3,640 hours TIS New Step 5 Post-Modification Initial Inspection time = 3,640 + 1,600 = 5,240 hours TIS. Retained Step 6 Post-Modification Inspection interval: Since the winglets are removed E:\FR\FM\09AUP1.SGM 09AUP1 Federal Register / Vol. 71, No. 153 / Wednesday, August 9, 2006 / Proposed Rules the Post-Modification Inspection interval remains at 800/1,600 hours TIS. New Step 7 replacement time = 8,000 – 360= 7,640 hours TIS Use the Retained Step 2 interval, the New Step 5 time, and the Retained Step 6 interval to make appropriate logbook entries for the pre- and post-modification intervals, using the format presented in Steps 2.d., 4.c., and 6.c. If you have not removed the winglets, then calculate new, reduced hours for Step 1, 2, 4, 5, 6, and 7 above, as applicable, based on the winglet usage factor listed in Table 2 of paragraph (c)(4) of this AD and Appendix 2 of this AD. Repetitively inspect at the appropriate interval listed in the step above divided by the winglet usage factor. EXAMPLE: An AT–502B, S/N 502B–0550, that has not had P/N 20998–1/-2 web plate installed and has had winglets on since new. The winglet usage factor is: 1.2 New Step 1 Pre-modification initial inspection time: 1,600 ÷ ( 1.2 = 1,333 hours TIS. New Step 2 Pre-modification inspection interval: 600 ÷ ( 1.2 = 500 hours TIS. New Step 4 Modification time: 4,000 ÷ ( 1.2 = 3,333 hours TIS. New Step 5 Post-modification initial inspection time: 3,333 + 1,333 (1,600 ÷ (1.2) = 4,666 hours TIS. New Step 6 Post-modification inspection interval: 800 ÷ (1.2 = 667 hours TIS. New Step 7 Replacement time: 8,000 ÷ ( 1.2 = 6,667 hours TIS Use the reduced hours you calculate in New Step 2, New Step 5, and New Step 6 to make appropriate logbook entries for the preand post-modification inspection intervals, using the format presented in Steps 2.d., 4.c., and 6.c above. Issued in Kansas City, Missouri, on August 3, 2006. John R. Colomy, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. E6–12945 Filed 8–8–06; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2004–20007; Directorate Identifier 2004–CE–50–AD] RIN 2120–AA64 Airworthiness Directives; Air Tractor, Inc. Model AT–602 Airplanes Federal Aviation Administration (FAA), DOT. jlentini on PROD1PC65 with PROPOSAL AGENCY: ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of the comment period. You may examine the comments on this proposed AD in the AD docket on the Internet at https://dms.dot.gov. SUMMARY: The FAA proposes to revise an earlier proposed airworthiness directive (AD) that applies to all Air Tractor, Inc. (Air Tractor) Model AT– 602 airplanes. The earlier NPRM would have required you to repetitively inspect (using the eddy current method) the wing center splice joint two outboard fastener holes on both of the wing main spar lower caps for fatigue cracking; repair or replace any wing main spar lower cap where fatigue cracking is found; and report any fatigue cracking found. The NPRM resulted from fatigue cracking at the wing center splice joint outboard fastener hole in one of the wing main spar lower caps. Since issuing the NPRM, the FAA has received and evaluated new information that decreases the compliance time to initially inspect certain serial numbers. This proposed AD includes the new compliance times in the table located in paragraph (e)(2) of this AD. Since these actions impose an additional burden over that proposed in the earlier NPRM, we are reopening the comment period to allow the public the chance to comment on these additional actions. DATES: We must receive any comments on this proposed AD by October 10, 2006. ADDRESSES: Use one of the following to submit comments on this proposed AD: • DOT Docket Web site: Go to https://dms.dot.gov and follow the instructions for sending your comments electronically. • Government-wide rulemaking Web site: Go to https://www.regulations.gov and follow the instructions for sending your comments electronically. • Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL–401, Washington, DC 20590– 0001. • Fax: 1–202–493–2251. • Hand Delivery: Room PL–401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. To get service information identified in this AD, contact Air Tractor, Inc. at P.O. Box 485, Olney, Texas 76374; telephone: (940) 564–5616; or facsimile: (940) 564–5612. FOR FURTHER INFORMATION CONTACT: Andrew McAnaul, Aerospace Engineer, ASW–150 (c/o MIDO–43), 10100 Reunion Place, Suite 650, San Antonio, Texas 78216; telephone: (210) 308– 3365; facsimile: (210) 308–3370. SUPPLEMENTARY INFORMATION: Comments Invited We invite you to send any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include the docket number, ‘‘FAA–2004–20007; Directorate Identifier 2004–CE–50–AD’’ at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments. We will post all comments we receive, without change, to https:// dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed rulemaking. Discussion The FAA received a report of fatigue cracking of the wing main spar lower cap at the wing center splice joint outboard fastener hole on one Air Tractor Model AT–602 airplane. The airplane had 2,895 hours time-in-service (TIS) at the time the cracking was discovered. The fatigue cracking is similar to that found on other Air Tractor airplane model wings. Cracks in the wing main spar lower cap could result in failure of the spar cap and lead to wing separation and loss of control of the airplane. The following table contains AD actions that address the wing spar safe life of the Air Tractor airplane fleet: RELATED AD ACTIONS AD No. Affected Air Tractor model airplanes 2000–14–51 ....................................................... 2001–10–04 ....................................................... AT–501, AT–502, and AT–502A ...................... AT–400, AT–500, and AT–800 Series ............. VerDate Aug<31>2005 18:06 Aug 08, 2006 Jkt 208001 45467 PO 00000 Frm 00031 Fmt 4702 Sfmt 4702 Status Superseded by AD 2001–10–04. Revised by AD 2001–10–04 R1. E:\FR\FM\09AUP1.SGM 09AUP1

Agencies

[Federal Register Volume 71, Number 153 (Wednesday, August 9, 2006)]
[Proposed Rules]
[Pages 45457-45467]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E6-12945]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19961; Directorate Identifier 2004-CE-48-AD]
RIN 2120-AA64

Airworthiness Directives; Air Tractor, Inc. Models AT-501, AT-
502, AT-502A, AT-502B, and AT-503A Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of
Transportation (DOT).

ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of
the comment period.

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to revise an earlier proposed airworthiness
directive (AD) that applies to certain Air Tractor, Inc. (Air Tractor)
Models AT-502, AT-502A, AT-502B, and AT-503A airplanes, which proposes
to supersede AD 2002-26-05. AD 2002-26-05 lowers the safe life for the
wing lower spar caps for Models AT-502, AT-502A, AT-502B, and AT-503A
airplanes and those that incorporate or have incorporated Marburger
Enterprises, Inc. (Marburger) winglets. AD 2002-26-05 also requires you
to eddy-current inspect the wing lower spar caps immediately before
modifying to correct any crack in a bolt hole before it extends to the
modified center section of the wing and report the results of the
inspection to the FAA if cracks are found. AD 2002-11-05 R1 currently
requires similar action on Model AT-501 airplanes. Since issuing the
earlier NPRM, we determined that Model AT-501 airplanes should be added
to the Applicability section of this proposed AD and that this proposed
AD should also supersede AD 2002-11-05 R1. We have revised the
alternative method of compliance (AMOC) to include inspection
procedures for airplanes that have or have had Marburger winglets
installed. We have also updated the safe life of the replacement and
new production spar cap based on additional data we have received from
the manufacturer. Since these actions impose an additional burden over
that proposed in the earlier NPRM, we are reopening the comment period
to allow the public the chance to comment on these additional actions.

DATES: We must receive any comments on this proposed AD by October 10,
2006.

ADDRESSES: Use one of the following addresses to comments on this
proposed AD:
DOT Docket Web site: Go to https://dms.dot.gov and follow
the instructions for sending your comments electronically.
Government-wide rulemaking Web site: Go to https://
www.regulations.gov and follow the instructions for sending your
comments electronically.
Mail: Docket Management Facility, U.S. Department of
Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401,
Washington, DC 20590-0001.
Fax: (202) 493-2251.
Hand Delivery: Room PL-401 on the plaza level of the
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this proposed AD, contact Air
Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374; or Marburger
Enterprises, Inc., 1227 Hillcourt, Williston, North Dakota 58801;
telephone: (800) 893-1420 or (701) 774-0230; facsimile: (701) 572-2602.

FOR FURTHER INFORMATION CONTACT: Direct all questions to:
For the airplanes that do not incorporate and never have
incorporated Marburger Enterprises, Inc. winglets: Rob Romero,
Aerospace Engineer, FAA, Fort Worth Airplane Certification Office, 2601
Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone: (817) 222-
5102; facsimile: (817) 222-5960; e-mail: robert.a.romero@faa.gov; and
For airplanes that incorporate or have incorporated
Marburger Enterprises, Inc. winglets: John Cecil, Aerospace Engineer,
Los Angeles Aircraft Certification Office, FAA, 3960 Paramount
Boulevard, Lakewood, California 90712; telephone: (562) 627-5228;
facsimile: (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or
arguments regarding this proposed AD. Send your comments to an address
listed under the ADDRESSES section. Include the docket number, ``FAA-
2004-19961; Directorate Identifier 2004-CE-48-AD'' at the beginning of
your comments. We specifically invite comments on the overall
regulatory, economic, environmental, and energy aspects of this
proposed AD. We will consider all comments received by the closing date
and may amend this proposed AD in light of those comments.
We will post all comments we receive, without change, to https://
dms.dot.gov, including any personal information you provide. We will
also post a report summarizing each substantive verbal contact we
receive concerning this proposed AD.

Discussion

Prior to issuing this supplemental notice of proposed rulemaking
(NPRM), we issued a proposal to amend part 39 of the Federal Aviation
Regulations (14 CFR part 39) to include an AD that would apply to
certain Air Tractor Models AT-502, AT-502A, AT-502B, and AT-503A
airplanes. That proposal was published in the Federal Register as an
NPRM on February 9, 2005 (70 FR 6786). The NPRM proposed to supersede
AD 2002-26-05 with a new AD that would retain the actions required in
AD 2002-26-05, add additional airplanes to the applicability, and
incorporate an AMOC to the actions retained from AD 2002-26-05.
AD 2002-26-05, Amendment 39-12991 (68 FR 18, January 2, 2003),
currently applies to certain Air Tractor Models AT-502, AT-502A, AT-
502B, and AT-503A airplanes. AD 2002-26-05 supersedes AD 2002-11-03 and
requires the following:
Maintaining the original requirements from AD 2002-11-03
for a lowered safe life, inspection, replacement/modification, and if
cracks are found, reporting the results to the FAA;
Further lowering the safe life for the wing lower spar cap
established in AD 2002-11-03 for Models AT-502, AT-502B, and AT-503A
airplanes; and
Expanding the applicability of Models AT-502A and AT-502B
airplanes to account for future manufactured airplanes.
With this supplemental NPRM we are also proposing to supersede AD
2002-11-05 R1, Amendment 39-14564 (71 FR 19629, April 17, 2006), which
currently applies to certain Air Tractor Model AT-501 airplanes. We
issued AD 2002-11-05 R1 to revise AD 2002-11-05 to remove AT-400 series
and Models AT-802 and AT-802A airplanes from the applicability because
separate AD actions were issued for those airplanes.

[[Page 45458]]

AD 2002-11-05 R1 retains the actions required in AD 2002-11-05 for
Model AT-501 airplanes.
The following is a list of ADs that have been issued to date that
are related to the wing spar inspection and safe life on Air Tractor
airplanes:

----------------------------------------------------------------------------------------------------------------
Affected air tractor model
AD No. airplanes Status
----------------------------------------------------------------------------------------------------------------
2000-14-51..................... AT-501, AT-502, and AT-502A...... Superseded by AD 2001-10-04.
2001-10-04..................... AT-400, AT-500, and AT-800 Series Revised by AD 2001-10-04 R1.
2001-10-04 R1.................. AT-400, AT-500, and AT-800 Series Superseded by AD 2002-11-05.
2002-11-05..................... AT-400, AT-401, AT-401B, AT-402, Revised by AD 2002-11-05 R1.
AT-402A, AT-402B, AT-501, AT-
802, and AT-802A.
2002-13-02..................... AT-300, AT-301, AT-302, AT-400, Superseded by AD 2003-06-01.
and AT-400A Airplanes.
2002-11-03..................... AT-502, AT-502A, AT-502B, and AT- Superseded by AD 2002-26-05.
503A.
2002-26-05..................... AT-502, AT-502A, AT-502B, and AT- Current.
503A.
2003-06-01..................... AT-300, AT-301, AT-302, AT-400, Current.
and AT-400A.
2002-11-05 R1.................. AT-501........................... Current.
2006-08-08..................... AT-400, AT-401, AT-401B, AT-402, Current.
AT-402A, and AT-402B.
2006-08-09..................... AT-802 and AT-802A............... Current.
----------------------------------------------------------------------------------------------------------------

You may view these ADs at the following Internet Web site
addresses: https://www.airweb.faa.gov/Regulatory_and_Guidance_
Library/rgAD.nsf/MainFrame?OpenFrameSet or https://www.gpoaccess.gov/fr/
index.html.

Comments

We provided the public the opportunity to participate in developing
the proposed AD on Air Tractor Models AT-502, AT-502A, AT-502B, and AT-
503A airplanes. The following presents the comments received on this
earlier proposed AD and FAA's response to each comment:

Comment Issue No. 1: Allow Repetitive Inspection and an Upper Life
Limit on the New Cap

Lewis Air Service states there is a need to incorporate an
alternative solution that includes repetitive inspections and an upper
life limit on the new cap. Based on the way the NPRM is currently
written, the commenter believes the low cap replacement time is too
burdensome and not cost effective.
Although we agree that repetitive inspections may reduce the
economic impact and minimize the risk of reduced agricultural
production, this will not meet the safety intent of this proposed AD.
We determined that reliance on critical repetitive inspections carries
an unnecessary safety risk when parts replacement or modifications
exist. In determining what inspections are critical, the FAA considers
(1) the safety consequences of the airplane if the known problem is not
detected by the inspection; (2) the reliability of the inspection, such
as the probability of not detecting the known problem; (3) whether the
inspection area is difficult to access; and (4) the possibility of
damage to an adjacent structure as a result of the problem.
Since the initial publication of the earlier proposed AD, Air
Tractor has completed fatigue testing on the replacement spar cap. The
life of the cap has been updated in this proposed AD to reflect the
results of this testing and subsequent analysis.
We are not changing this proposed AD based on this comment but are
changing it based on new data from the manufacturer.

Comment Issue No. 2: Proposed AD Is Not Necessary

M&M Air Service states that they operate eight different Air
Tractor airplanes and to date have not found any cracks. The commenter
indicates that the proposed rulemaking is confusing, not cost
beneficial, and excessive.
Based on these comments, we infer that the commenter wants the NPRM
withdrawn.
We do not agree with the commenter. Fatigue analysis/testing/fleet
history shows that the wing spar will crack and fail over time. The
commenter's airplanes not cracking to date does not prevent the unsafe
condition from developing on the commenter's airplanes or other
airplanes of the same type design in the future.
To date, we have received over 50 reports of cracked spar caps on
AT-502 series airplanes and one report of complete wing separation. We
realize that there are many different wing configurations in-service on
these airplanes and each has different requirements. However, analysis
shows that the airplane could fail in the affected area based on the
design and normal utilization of the type design airplanes.
We are not changing this proposed AD based on this comment.

Comment Issue No. 3: Compliance Time To Accommodate Flying Schedules

The National Agricultural Aviation Association requests the FAA
consider the flying schedules of the airplanes and accommodate a
program that can be done during the off-season. The commenter suggests
the FAA allow repetitive inspections until an ultimate solution is
reached, assuming no cracks are found.
We have considered the importance of the financial and operational
impact this proposed rulemaking may have on owners and operators and,
in this specific case, aerial application businesses. This proposed AD
uses inspections to manage the safety of the wing centerline joint
instead of reducing the compliance times for replacing parts. However,
this approach cannot be used indefinitely. Extending the service life
of fatigue-critical, primary structure areas requires not only ensuring
the safety of the area being inspected or modified, but also ensuring
the safety of the complete structure when extending the service life.
Fatigue analysis shows that the safe life is the solution to the
unsafe condition, not repetitive inspections over the life of the
airplane. For eligible airplanes, we are providing an AMOC that
provides an aggressive repetitive inspection program until 8,000 hours
time-in-service (TIS), provided no cracks are found.
The FAA has shown a history of accommodating flying schedules
through AMOCs on previous ADs for this subject. We will continue to
consider AMOCs provided they maintain a level of safety acceptable to
the FAA.
For the replacement spar cap, we have received new data that
justifies a much higher safe life than was previously published in the
NPRM.

[[Page 45459]]

We are not changing this proposed AD based on this comment.

Comment Issue No. 4: Lack of Wing Life-Limit Information

Julie Broussard of Lewis Flying and Maintenance Service, Inc.,
states that she was never informed in writing of a 1,600 hour safe life
or replacement life of 8,000 hours TIS for the AT-502 wing. The
commenter also urges the FAA to make the manufacturer ``fix the wing.''
We issued AD 2002-26-05, Amendment 39-12991 (68 FR 18, January 2,
2003), which applies to Air Tractor Models AT-502, AT-502A, AT-502B,
and AT-503A airplanes. That AD lowers the safe life for the wing lower
spar caps to 1,650 hours TIS. AD 2002-26-05 supersedes AD 2002-11-03,
Amendment 39-12764 (67 FR 38371, June 4, 2002). We also issued Special
Airworthiness Information Bulletin (SAIB) CE-05-28, dated January 21,
2005, announcing an AMOC to AD 2002-26-05. The AMOC allows an
inspection program instead of the safe life replacement program
required by AD 2002-26-05, which allows operation of a modified wing up
to 8,000 hours TIS, provided no cracks are found during required
inspections.
We are legally bound to notify the public of an AD through
publication in the Federal Register. AD 2002-26-05 was published in the
Federal Register on January 2, 2003. In the past, we have sent copies
of ADs and SAIBs to registered owners of the affected airplanes, which
could be a bank or holding company. This may be the reason the
commenter did not receive notification of the change in the safe life
limit and replacement schedule.
This supplemental NPRM is still only a proposal at this time. The
previous NPRM on this subject was published in the Federal Register on
February 9, 2005 (70 FR 6786).
We will always encourage modifications that incorporate design
changes that make critical parts stronger and safer. However, our
responsibility is to address the continued operational safety of the
airplane fleet, ensure that current design regulations are met, and
correct any unsafe conditions.
Establishing a safe life and an option of an aggressive repetitive
inspection schedule until 8,000 hours TIS (provided no cracks are
found) meets the FAA's responsibility. Further, the replacement spar
cap has been substantiated to a much higher safe life than previously
published.
We are not changing this proposed AD based on this comment.

Comment Issue No. 5: New Production Airplanes Have a 27 Percent
Increase in Safe Life

The National Transportation Safety Board (NTSB) questions the
rationale for new production AT-502B airplanes having a 27 percent
increase in the safe life limit on the wing from 1,650 hours TIS to
2,100 hours TIS. The commenter also states a concern for the
conservatism in the initial and repetitive inspection program.
Other items of concern to the commenter are:
The wording proposed in section (e)(2) of the earlier
proposed AD may allow for inspections to continue indefinitely. The
commenter states that airplanes using the AMOC who find cracks should
report them to the FAA.
Airplanes that have been modified with a replacement cap
should follow the inspection program for later serial number airplanes.
There has been nothing done to address the use of winglets
as it applies to inspection intervals.
The safe life for new production AT-502B airplanes was determined
as a result of fatigue testing performed by the manufacturer. The
initial and repetitive inspection program was based on a thorough
damage tolerance analysis using a validated load spectrum and coupon
testing.
It should be noted that since publication of the earlier NPRM, the
manufacturer has completed more extensive testing, and we are now
proposing a safe life for new production AT-502B airplanes that
represents much more than the 27 percent increase the commenter states.
We do not agree that paragraph (e)(2) of the previously proposed AD
allowed for indefinite inspections. Paragraph (e)(2) of the proposed AD
refers to Appendix 2, which has clearly defined upper limits on
inspection times (8,000 hours TIS for eligible airplanes).
We agree that any cracks detected should be reported to the FAA. We
are retaining the reporting requirement from the earlier NPRM in this
proposed AD.
Airplanes with replacement spar caps, as well as new production
airplanes, are no longer required to follow an inspection program.
We agree that we did not address an inspection program for
airplanes with winglets installed. We are revising this proposed AD to
include an AMOC inspection program for airplanes that have or have had
winglets installed. Further, this proposed AD states that airplanes
with the new or replacement spar caps are not eligible to have the
winglet STC installed without proper fatigue substantiation.

Comment Issue No. 6: Include Model AT-501 Airplanes in the
Applicability

Leland Snow, President of Air Tractor, Inc., states that Model AT-
501 airplanes should be included in the Applicability section and that
new airplanes should not have a safe life limit of 3,100 hours TIS.
The commenter states the costs for doing the inspection is too low.
The inspection typically costs from $450 to $550. Parts cost for the
replacement spar cap is approximately $16,500 plus approximately
$16,500 for labor (a total of $33,000).
The commenter also states that winglets should be removed before
allowing the AMOC.
We agree with the commenter that Model AT-501 airplanes should be
included in the Applicability section. We also agree to update the Cost
Impact section. We are revising this proposed AD to include those
changes.
We do not agree that airplanes with winglets installed should be
excluded from the AMOC. We are adding an AMOC inspection program in
this proposed AD to cover airplanes that have winglets installed
following Supplemental Type Certificate (STC) SA00490LA.

Comment Issue No. 7: Torsion Loads

John R. Janssen states that torsion loads need to be accounted for
to properly address the wing safe life limit for the affected
airplanes.
We agree with the commenter that the torsion load is a contributing
factor to the fatigue life of the wings, as are all the other loads
(ground, gust, maneuver, etc.). These loads have been accounted for in
the load spectrum that was used in developing the inspection program
and the life of the new/replacement spar cap.
We are not changing this proposed AD based on this comment.

Comment Issue No. 8: Marburger Winglets

Lewis Broussard, Owner, Lewis Flying and Maintenance Service, Inc.,
states that installing Marburger Enterprise, Inc. winglets increases
the safe life of the wing.
We do not agree with the commenter. We have data that shows adding
winglets increases the operating stresses at the wing root and
consequently leads to a reduced safe life.
We are not changing this proposed AD based on this comment.

Comment Issue No. 9: AMOC Should Apply to Airplanes With Winglets

Rick Marburger of Marburger Enterprises, Inc., states that
airplanes

[[Page 45460]]

with winglets installed should be included in the AMOC repetitive
inspection program.
We agree with the commenter. We included procedures in the AMOC
repetitive inspection program to address airplanes that have or have
had winglets installed.
We are revising this proposed AD to incorporate this change.

Comment Issue No. 10: Unfair Safe Life Limit for the New Spar Cap

Tom Miller of Ingalls Aerial Sprayers, Inc., states the safe life
limit of 3,100 hours TIS for the new/replacement spar cap is unfair.
Numerous other commenters have similar concerns. The commenters state
the new design should be given a safe life limit that is equivalent to
the old design, which is 8,000 hours TIS.
We agree with the commenters. The 3,100-hour TIS safe life limit
was based on data submitted by Air Tractor and approved by the FAA.
However, since the earlier proposed AD was published, Air Tractor began
a new test program using a recently validated load spectrum to
determine a new safe life for this design configuration. That testing
has been completed and the new safe life limit is being published in
this proposed AD.
We are revising this proposed AD to incorporate this change.

Relevant Service Information

The following service information from AD 2002-11-05 R1 and the
previous NPRM are still valid for this supplemental NPRM:
Snow Engineering Drawing Number 21050;
Snow Engineering Service Letters 197 or
205, both revised March 26, 2001; and
Snow Engineering Service Letter 244, dated April
25, 2005.
Snow Engineering Co. has a licensing agreement with Air Tractor
that allows them to produce technical data for use on Air Tractor
products.

FAA's Determination and Requirements of This Proposed AD

Since issuing the earlier NPRM, we determined that Model AT-501
airplanes should be added to the Applicability section. We also
developed an AMOC to the requirements of AD 2002-26-05 for airplanes
that have or have had winglets installed. We are extending the safe
life for new production airplanes and replacement spar caps.
After examining the circumstances and reviewing all available
information related to the incidents described above, we have
determined that:
The unsafe condition referenced in this document exists or
could develop on other Air Tractor Models AT-501, AT-502, AT-502A, AT-
502B, and AT-503A airplanes of the same type design that are on the
U.S. registry;
We should change this proposed AD to include Model AT-501
airplanes in the Applicability section and revise the AMOC.
We should take AD action to correct this unsafe condition.

The Supplemental NPRM

Adding additional models to the Applicability section goes beyond
the scope of what was originally proposed in the earlier NPRM.
Therefore, we are reopening the comment period and allowing the public
the chance to comment.
This proposed AD would supersede AD 2002-26-05 and AD 2002-11-05 R1
with a new AD that would:
Retain the actions required in AD 2002-26-05 and AD 2002-
11-05 R1;
Add additional airplanes to the Applicability section;
Incorporate a revised AMOC to include inspection
procedures for airplanes that have or have had winglets installed
following STC SA00490LA; and
Extend the safe life for new production airplanes and
replacement spar caps.
The following table summarizes the effects this proposed AD would
have on the airplane models affected by this proposed AD:

----------------------------------------------------------------------------------------------------------------
Proposed
Model action
-------------------------------------------------------------------------------------------------------- ----------
AT-501....................................... Supersede AD 2002-11-05 R1.
Retain the safe lives from AD 2002-11-05 R1.
Provide an AMOC that allows extension of the
safe life through an inspection and modification
program.
AT-502....................................... Supersede AD 2002-26-05.
Retain the safe lives from AD 2002-26-05 and add
S/Ns to applicability. AD 2002-26-05 provided safe lives
for S/Ns 0003 through 0236. Proposed action applies the
same safe life to all S/Ns beginning with 0003.
Provide an AMOC that allows extension of the
safe life through an inspection and modification
program.
AT-502A...................................... Supersede AD 2002-26-05.
Retain the safe lives from AD 2002-26-05.
Provide an AMOC that allows extension of the
safe life through an inspection and modification
program.
AT-502B...................................... Supersede AD 2002-26-05.
Retain the safe lives from AD 2002-26-05 for S/
Ns 0187 through 0654, except 0643.
Increase the safe lives beyond those listed in
AD 2002-26-05 for S/Ns 0655 and greater, as well as S/N
0643.
Add requirement to cold work outboard wing
center splice block bolt holes in the lower spar cap on
S/Ns 0643 and 0655 through 0692.
Provide an AMOC that allows extension of the
safe life through an inspection and modification program
for S/Ns 187 through 654, except 643.
AT-503A...................................... Supersede AD 2002-26-05.
Retain the safe lives from AD 2002-26-05.
Provide an AMOC that allows extension of the
safe life through an inspection and modification
program.
----------------------------------------------------------------------------------------------------------------

Costs of Compliance

We estimate that this proposed AD affects approximately 500
airplanes in the U.S. registry.
We estimate the following costs to do each proposed inspection:

[[Page 45461]]

----------------------------------------------------------------------------------------------------------------
Total cost per
Labor cost Parts cost airplane Total cost on U.S. operators
----------------------------------------------------------------------------------------------------------------
8 work-hours x $80 per hour = No parts required for $640 $640 x 500 = $320,000.
$640. inspection.
----------------------------------------------------------------------------------------------------------------

We estimate the following costs to do the proposed modification:

--------------------------------------------------------------------------------------------------------------------------------------------------------
Labor cost Parts cost Total cost per airplane Total cost on U.S. operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
120 work-hours x $80 per hour = Approximately $3,700 $9,600 + $3,700 = $13,300 $13,300 x 500 = $6,650,000.00.
$9,600.
--------------------------------------------------------------------------------------------------------------------------------------------------------

We estimate the following costs to do the proposed replacement:

--------------------------------------------------------------------------------------------------------------------------------------------------------
Labor cost Parts cost Total cost per airplane Total cost on U.S. operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
254 work-hours x $80 per hour = Approximately $16,500.. $20,320 + $16,500 = $36,820 $36,820 x 500 = $18,410,000.00.
$20,320.
--------------------------------------------------------------------------------------------------------------------------------------------------------

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in
subtitle VII, part A, subpart III, section 44701, ``General
requirements.'' Under that section, Congress charges the FAA with
promoting safe flight of civil aircraft in air commerce by prescribing
regulations for practices, methods, and procedures the Administrator
finds necessary for safety in air commerce. This regulation is within
the scope of that authority because it addresses an unsafe condition
that is likely to exist or develop on products identified in this
rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship
between the national Government and the States, or on the distribution
of power and responsibilities among the various levels of government.
For the reasons discussed above, I certify that the proposed
regulation:
1. Is not a ``significant regulatory action'' under Executive Order
12866;
2. Is not a ``significant rule'' under the DOT Regulatory Policies
and Procedures (44 FR 11034, February 26, 1979); and
3. Will not have a significant economic impact, positive or
negative, on a substantial number of small entities under the criteria
of the Regulatory Flexibility Act.
We prepared a regulatory evaluation of the estimated costs to
comply with this proposed AD and placed it in the AD docket.

Examining This Proposed AD Docket

You may examine the AD docket that contains the proposed AD, the
regulatory evaluation, any comments received, and other information on
the Internet at https://dms.dot.gov; or in person at the Docket
Management Facility between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays. The Docket Office (telephone (800) 647-5227)
is located at the street address stated in the ADDRESSES section.
Comments will be available in the AD docket shortly after receipt.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the Federal Aviation Administration proposes to amend 14
CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13 [Amended]

2. FAA amends Sec. 39.13 by removing Airworthiness Directive (AD)
2002-26-05, Amendment 39-12991 (68 FR 18, January 2, 2003) and AD 2002-
11-05 R1, Amendment 39-14564 (71 FR 19628, April 17, 2006), and by
adding a new AD to read as follows:

Air Tractor, Inc.: Docket No. FAA-2004-19961; Directorate Identifier
2004-CE-48-AD.

Comment Due Date

(a) We must receive comments on this proposed airworthiness
directive (AD) by October 10, 2006.

Affected AD

(b) This AD supersedes AD 2002-26-05, Amendment 39-12991, and AD
2002-11-05 R1, Amendment 39-14564.

Applicability

(c) This AD applies to certain Models AT-501, AT-502, AT-502A,
AT-502B, and AT-503A airplanes. Use Table 1 in paragraph (c)(1) of
this AD for airplanes that do not incorporate and never have
incorporated Marburger Enterprises, Inc. (Marburger) winglets. Use
Table 2 in paragraph (c)(4) of this AD for certain AT-500 series
airplanes that incorporate or have incorporated Marburger winglets.
(1) The following table applies to airplanes (certificated in
any category) that do not incorporate and never have incorporated
Marburger winglets along with the safe life (presented in hours
time-in-service (TIS)) of the wing lower spar cap for all affected
airplane models and serial numbers:

[[Page 45462]]

Table 1.--Safe Life for Airplanes That Do Not Incorporate and Never Have Incorporated Marburger Winglets
----------------------------------------------------------------------------------------------------------------
Model Serial Nos. Wing lower spar cap safe life
----------------------------------------------------------------------------------------------------------------
AT-501............................... 0002 through 0061...................... 4,531 hours TIS.
AT-501............................... All serial numbers beginning with 0062. 7,693 hours TIS.
AT-502............................... All serial numbers beginning with 0003. 1,650 hours TIS.
AT-502A.............................. All serial numbers beginning with 0158. 1,650 hours TIS.
AT-502B.............................. 0187 through 0654, except 0643......... 1,650 hours TIS.
AT-502B.............................. 0643, and 0655 through 0692............ 9,000 hours TIS.
AT-502B.............................. 0693 through 0701...................... 9,500 hours TIS.
AT-502B.............................. All serial numbers beginning with 0702. 9,800 hours TIS.
AT-503A.............................. All serial numbers beginning with 0067. 1,650 hours TIS.
----------------------------------------------------------------------------------------------------------------

(2) If piston-powered airplanes have been converted to turbine
power, you must use the limits for the corresponding serial number
(S/N) turbine-powered airplanes.
(3) Airplanes that have been modified to install lower spar
caps, part numbers (P/N) 21058-1 and 21058-2, should use a safe life
of 9,800 hours TIS.
(4) The following table applies to airplanes (certificated in
any category) that incorporate or have incorporated Marburger
winglets. These winglets are installed following Supplemental Type
Certificate (STC) SA00490LA. Use the winglet usage factor in Table 2
of this paragraph, the safe life specified in Table 1 in paragraph
(c)(1) of this AD, and the instructions included in Appendix 1 to
this AD to determine the new safe life of airplanes that incorporate
or have incorporated Marburger winglets:

Table 2.--Winglet Usage Factor To Determine the Safe Life for Airplanes That Incorporate or Have Incorporated
Marburger Winglets Installed Following STC SA00490LA
----------------------------------------------------------------------------------------------------------------
Winglet usage
Model Serial Nos. factor
----------------------------------------------------------------------------------------------------------------
AT-501........................................ 0002 through 0061............................... 1.6
AT-501........................................ All serial numbers beginning with 0062.......... 1.6
AT-502........................................ 0003 through 0236............................... 1.6
AT-502A....................................... 0158 through 0238............................... 1.6
AT-502A....................................... All serial numbers beginning with 0239.......... 1.2
AT-502B....................................... All serial numbers beginning with 0187.......... 1.2
----------------------------------------------------------------------------------------------------------------

(5) Model AT-502B airplanes, S/N 0643, all S/Ns beginning with
0655, and all other airplanes that have been modified with
replacement spar caps, P/N 21058-1 and P/N 21058-2, are not eligible
to have STC SA00490LA installed without additional fatigue data
being provided to the FAA at the address in paragraph (f) of this
AD.

Unsafe Condition

(d) This AD is the result of service reports and analysis done
on wing lower spar caps of Air Tractor, Inc. airplanes. The actions
specified by this AD are intended to prevent fatigue cracks from
occurring in the wing lower spar cap before the established safe
life is reached. Fatigue cracks in the wing lower spar cap, if not
detected and corrected, could result in failure of the spar cap and
lead to wing separation and loss of control of the airplane.

Compliance

(e) To address this problem, you must do the following:

------------------------------------------------------------------------
Actions Compliance Procedures
------------------------------------------------------------------------
(1) For all affected For airplanes Airplane Records
airplanes: Modify the previously affected Modification: The
applicable airplane records by AD 2002-26-05: owner/operator
(logbook) as follows to Do the logbook holding at least a
show the reduced safe life entry within the private pilot
for the wing lower spar cap next 10 hours TIS certificate as
(use the information from after January 15, authorized by
Table 1 in paragraph 2003 (the effective section 43.7 of the
(c)(1), Table 2 in date of AD 2002-26- Federal Aviation
paragraph (c)(4), and 05). For airplanes Regulations (14 CFR
Appendix 1 of this AD, as not previously 43.7) may modify
applicable): affected by AD 2002- the airplane
(i) Incorporate the 26-05: Do the records as
following into the airplane logbook entry specified in
logbook ``In accordance within the next 10 paragraph (e)(1) of
with AD **-**-** (AD 2002- hours TIS after the this AD. Make an
26-05 or AD 2002-11-05, as effective date of entry into the
applicable) the wing lower this AD, unless airplane records
spar cap is life limited to already done. The showing compliance
----.'' Insert the logbook language with this portion
applicable safe life number for AT-501 of the AD in
from the applicable tables airplanes is accordance with
in paragraphs (c)(1) and referenced as AD section 43.9 of the
(c)(4) of this AD and 2002-11-05 instead Federal Aviation
Appendix 1 of this AD. of AD 2002-11-05 R1 Regulations (14 CFR
(ii) If, as of the time of to maintain 43.9). Spar Cap
the logbook entry continuity and Replacement: Do the
requirement of paragraph assures no further replacement when
(e)(1)(i) of this AD, your action is necessary. the safe life is
airplane is over or within reached following
50 hours of the safe life, Snow Engineering
an additional 50 hours TIS Drawing Number
after the effective date of 21050, Snow
this AD is allowed to do Engineering Service
the replacement. Letters 197 or 205, both revised
March 26, 2001, as
applicable. The
owner/operator may
not do the spar cap
modification/
replacement, unless
he/she holds the
proper mechanic
authorization.

[[Page 45463]]

(2) For all affected Inspection schedule Procedures included
airplanes: To extend the included as part of as part of the AMOC
safe life of the wing lower the alternative in Appendix 2 to
spar cap, you may eddy- method of this AD.
current inspect and modify compliance (AMOC)
the wing lower spar cap. in Appendix 2 to
The inspection schedule and this AD.
modification procedures are
included in Appendix 2 to
this AD.
(3) For all affected Only if cracks are Send the form
airplanes: Report to the found, send the (Figure 1 of this
FAA any cracks detected as report within 10 AD) to FAA, Fort
the result of each days after the Worth Airplane
inspection required by inspection required Certification
paragraph (e)(2) of this AD in paragraph (e)(2) Office, Attn: Rob
on the form in Figure 1 of of this AD. Romero, 2601
this AD. The Office of Meacham Boulevard,
Management and Budget (OMB) Fort Worth, Texas
approved the information 76193-0150;
collection requirements telephone: (817)
contained in this 222-5102;
regulation under the facsimile: (817)
provisions of the Paperwork 222-5960.
Reduction Act and assigned
OMB Control Number 2120-
0056.
(4) For Model AT-502B Before accumulating Following Snow
airplanes, S/Ns 502B-0643, 2,000 hours TIS or Engineering Service
and 502B-0655 through 502B- within the next 100 Letter 244, dated April
hand and right-hand two effective date of 25, 2005.
outboard wing center splice this AD, whichever
block bolt holes (4 total) occurs later.
in the lower spar cap.
(5) For all affected Not applicable...... Not applicable.
airplanes: Airplanes that
have the two-part
modification done following
the applicable service
bulletins (Snow Engineering
Service Letters 197 or 205, both
revised March 26, 2001; or
Snow Engineering Service
Letter 244, dated
April 25, 2005), but have
over-sized outboard bolt
holes at the splice block,
must obtain an AMOC from
FAA as specified in
paragraph (f) of this AD to
determine applicable
inspection intervals.
------------------------------------------------------------------------

BILLING CODE 4910-13-P

[[Page 45464]]

[GRAPHIC] [TIFF OMITTED] TP09AU06.007

BILLING CODE 4910-13-C

Alternative Methods of Compliance (AMOC)

(f) The Manager, Fort Worth or Los Angeles Airplane
Certification Office (ACO), as applicable (see paragraphs (f)(1)(i)
and (f)(2)(ii) of this AD below for specific contacts), has the
authority to approve AMOCs for this AD, if requested using the
procedures found in 14 CFR 39.19.
(1) For information on any already approved AMOCs, contact:
(i) For the airplanes that do not incorporate and never have
incorporated Marburger Enterprises, Inc. winglets: Rob Romero,
Aerospace Engineer, FAA, Fort Worth Airplane Certification Office,
2601 Meacham Boulevard, Fort Worth, Texas 76193-0150; telephone:
(817) 222-5102; facsimile: (817) 222-5960; e-mail:
robert.a.romero@faa.gov.
(ii) For airplanes that incorporate or have incorporated
Marburger Enterprises, Inc. winglets: John Cecil, Aerospace
Engineer, Los Angeles Aircraft Certification Office, FAA,

[[Page 45465]]

3960 Paramount Boulevard, Lakewood, California 90712; telephone:
(562) 627-5228; facsimile: (562) 627-5210.
(2) AMOCs approved for AD 2001-10-04 and/or AD 2000-14-51 are
not considered approved for this AD.
(3) AMOCs approved for AD 2001-10-04 R1, AD 2002-11-03, AD 2002-
11-05, AD 2002-11-05 R1, or AD 2002-26-05 are considered approved
for this AD.

Special Flight Permit

(g) Under 14 CFR part 39.23, we are limiting the special flight
permits for this AD by the following conditions:
(1) Operate only in day visual flight rules (VFR).
(2) Ensure that the hopper is empty.
(3) Limit airspeed to 135 miles per hour (mph) indicated
airspeed (IAS).
(4) Avoid any unnecessary g-forces.
(5) Avoid areas of turbulence.
(6) Plan the flight to follow the most direct route.

Related Information

(h) To get copies of the documents referenced in this AD,
contact Air Tractor, Incorporated, P.O. Box 485, Olney, Texas 76374;
or Marburger Enterprises, Inc., 1227 Hillcourt, Williston, North
Dakota 58801. To view the AD docket, go to the Docket Management
Facility, U.S. Department of Transportation, 400 Seventh Street,
SW., Nassif Building, Room PL-401, Washington, DC, or on the
Internet at https://dms.dot.gov. The docket number is FAA-2004-19961.

Appendix 1 to Docket No. FAA-2004-19961

The following provides procedures for determining the safe life
for those Models AT-501, AT-502, AT-502A, and AT-502B airplanes that
incorporate or have incorporated Marburger Enterprises, Inc.
(Marburger) winglets. These winglets are installed in accordance
with Supplemental Type Certificate (STC) No. SA00490LA.
If you have removed the Marburger winglets before further flight
after the effective date of this AD or before the effective date of
this AD, do the following:
1. Review your airplane's logbook to determine your airplane's
time-in-service (TIS) with winglets installed per Marburger STC No.
SA00490LA. This includes all time spent with the winglets currently
installed and any previous installations where the winglet was
installed and later removed.

Example: A review of your airplane's logbook shows that you have
accumulated 350 hours TIS since incorporating the Marburger STC.
Further review of the airplane's logbook shows that a previous owner
had installed the STC and later removed the winglets after
accumulating 150 hours TIS. Therefore, your airplane's TIS with the
winglets installed is 500 hours.

If you determine that the winglet STC has never been
incorporated on your airplane, then your safe life is presented in
Table 1 in paragraph (c)(1) of this AD. Any future winglet
installation will be subject to a reduced safe life per these
instructions.
2. Determine your airplane's unmodified safe life from Table 1
in paragraph (c)(1) of this AD.

Example: Your airplane is a Model AT-502B, serial number (S/N) 0292.
From Table 1 in paragraph (c)(1) of this AD, the unmodified safe-
life of your airplane is 1,650 hours TIS.

All examples from hereon will be based on the Model AT-502B, S/N
0292 airplane.
3. Determine the winglet usage factor from Table 2 in paragraph
(c)(4) of this AD.

Example: Again, your airplane is a Model AT-502B, S/N 0292. From
Table 2 in paragraph (c)(4) of this AD, your winglet usage factor is
1.2.

4. Adjust the winglet TIS to account for the winglet usage
factor. Multiply the winglet TIS (result of Step 1 above) by the
winglet usage factor (result of Step 3 above).

Example: Winglet TIS is 500 hours x a winglet usage factor of 1.2.
The adjusted winglet TIS is 600 hours.

5. Calculate the winglet usage penalty. Subtract the winglet TIS
(result of Step 1 above) from the adjusted winglet TIS (result of
Step 4 above).

Example:
Adjusted winglet TIS - the winglet TIS = Winglet usage penalty.
(600 hours TIS) - (500 hours TIS) = (100 hours TIS).

6. Adjust the safe life of your airplane to account for winglet
usage. Subtract the winglet usage penalty (result of Step 5 above)
result from the unmodified safe life from Table 1 in paragraph
(c)(1) of this AD (the result of Step 2 above).

Example:
Unmodified safe life - winglet usage penalty = Adjusted safe
life.
(1,650 hours TIS) - (100 hours TIS) = (1,550 hours TIS).

7. If you remove the winglets from your airplane before further
flight or no longer have the winglets installed on your airplane,
the safe life of your airplane is the adjusted safe life (result of
Step 6 above). Enter this number in paragraph (e)(1)(i) of this AD
and the airplane logbook.
If you have the Marburger winglets installed as of the effective
date of this AD and plan to operate your airplane without removing
the winglets, do the following:
1. Review your airplane's logbook to determine your airplane's
TIS without the winglets installed.

Example: A review of your airplane's logbook shows that you have
accumulated 1,500 hours TIS, including 500 hours with the Marburger
winglets installed. Therefore, your airplane's TIS without the
winglets installed is 1,000 hours.

2. Determine your airplane's unmodified safe life from Table 1
in paragraph (c)(1) of this AD.

Example: Your airplane is a Model AT-502B, S/N 0292. From Table 1 in
paragraph (c)(1) of this AD, the unmodified safe life of your
airplane is 1,650 hours TIS.

All examples from hereon will be based on the Model AT-502B, S/N
0292 airplane.
3. Determine the winglet usage factor from Table 2 in paragraph
(c)(4) of this AD.

Example: Again, your airplane is a Model AT-502B, S/N 0292. From
Table 2 in paragraph (c)(4) of this AD, your winglet usage factor is
1.2.

4. Determine the potential winglet TIS. Subtract the TIS without
the winglets installed (result of Step 1 above) from the unmodified
safe life (result of Step 2 above).

Example:
Unmodified safe life - TIS without winglets = Potential winglet
TIS.
(1,650 hours TIS) - (1,000 hours TIS) = (650 hours TIS).

5. Adjust the potential winglet TIS to account for the winglet
usage factor. Divide the potential winglet TIS (result of Step 4
above) by the winglet usage factor (result of Step 3 above).

Example:
Potential winglet TIS / winglet usage factor = Adjusted
potential winglet TIS.
(650 hours TIS) / (1.2) = (541 hours TIS).

6. Calculate the winglet usage penalty. Subtract the adjusted
potential winglet TIS (result of Step 5 above) from the potential
winglet TIS (result of Step 4 above).

Example:
Potential winglet TIS - adjusted potential winglet TIS = Winglet
usage penalty.
(650 hours TIS) - (541 hours TIS) = (109 hours TIS).

7. Adjust the safe life of your airplane to account for the
winglet installation. Subtract the winglet usage penalty (result of
Step 6 above) from the unmodified safe life from Table 1 in
paragraph (c)(1) of this AD (the result of Step 2 above).

Example:
Unmodified safe life - winglet usage penalty = Adjusted safe
life.
(1,650 hours TIS) - (109 hours TIS) = (1,541 hours TIS).

8. Enter the adjusted safe life (result of Step 7 above) in
paragraph (e)(1)(i) of this AD and the airplane logbook.
If you install or remove the Marburger winglets from your
airplane in the future, do the following:
If, at anytime in the future, you install or remove the
Marburger winglets STC from your airplane, you must repeat the
procedures in this Appendix to determine the airplane's safe life.

APPENDIX 2--ALTERNATIVE METHOD OF COMPLIANCE (AMOC) TO DOCKET NO. FAA-
2004-19961

Optional Inspection Program

For all airplanes listed in this AD; except for Model AT-502B
airplanes, serial number (S/N) 0643 and all S/Ns beginning with
0655, and those airplanes that have been modified with the
replacement spar caps, part number (P/N) 21058-1 and P/N 21058-2;
you may begin a repetitive inspection interval program as an
alternative to the safe life requirement of this AD with the
following provisions:
For the Model AT-501 airplanes affected by this AD, you may
elect to follow this AMOC program and continue to operate your
airplane up to 8,000 hours TIS, provided you comply with this AMOC
in its entirety. If at the time of the effective date of this AD,
you are over 1,600 hours TIS (the time required for the first
inspection), you must inspect within 50 hours TIS. If at the time of
the

[[Page 45466]]

effective date of this AD, you are over 4,000 hours TIS (the time
required for 2-part modification), you must have the modification
done within 50 hours TIS. If you choose not to follow this
inspection program, then you must replace your lower spar caps and
associated hardware at the applicable safe life listed in this AD
following the procedures in paragraph (e).
For airplanes that do not and never have had Marburger
Enterprise, Inc. winglets installed following Supplemental Type
Certificate (STC) SA00490LA:
1. Upon accumulating 1,600 hours time-in-service (TIS) or within
the next 50 hours TIS after [effective date] (the effective date of
AD **-**-**), whichever occurs later, eddy-current inspect the
outboard two lower spar cap bolt holes following Snow Engineering
Process Specification 197, page 1, revised June 4, 2002;
pages 2 through 5, revised May 3, 2002. The inspection must be done
by one of the following:
a. A Level 2 or Level 3 inspector that is certified for eddy-
current inspection using the guidelines established by the American
Society for Nondestructive Testing or MIL-STD-410; or
b. A person authorized to do AD work and has completed and
passed the Air Tractor, Inc. training course on Eddy Current
Inspection on wing lower spar caps.
2. Repeat these inspections at intervals of (as applicable):
a. 800 hours TIS (all S/Ns except as noted in b); or
b. 600 hours TIS (S/Ns 502B-0187 through 502B-0618 that do not
have P/N 20998-1/2 web plate installed).
c. If the outboard two lower spar cap bolt holes have been cold
worked following Snow Engineering Service Letter 233, dated
May 18, 2004, then you may double (1,600 hours TIS or 1,200 hours
TIS, as applicable) the inspection interval (See Step 8--re: mid
cycle cold work).
d. Your logbook entry must include the work done and the
inspection intervals that are upcoming, as follows:
Following AD **-**-**, at XXXX {insert hours TIS of the initial
pre-modification inspection{time} hours TIS an eddy-current
inspection has been performed. As of now, the safe life listed in
the AD no longer applies to this airplane. This airplane must be
eddy-current inspected at intervals not to exceed {800/600/1,600/
1,200, as applicable{time} hours TIS. The first of these
inspections is due at {insert the total number of hours TIS the
first of these inspections is due{time} hours TIS.''
3. If at any time a crack is found, and:
a. The crack indication goes away by doing the modification
following the applicable sheet of Snow Engineering Modification--
Wing Centersplice--502, Drawing Number 20989, then you may modify
your center splice following Snow Engineering Drawing 20989. After
modification, proceed to Step 5.
b. The crack indication does not go away by doing the
modification following the applicable sheet of Snow Engineering
Modification--Wing Centersplice--502, Drawing Number 20989, you must
replace all parts and hardware listed in Step 7.
c. Report to the FAA any cracks found using the form in Figure 1
of this AD.
4. For all S/Ns, upon accumulating 4,000 hours TIS, you must:
a. Modify your center splice connection following the applicable
sheet of Snow Engineering Modification--Wing Centersplice--502,
Drawing Number 20989, unless already done following Snow Engineering
Service Letter 197 or 205, both revised March 26,
2001, as applicable. The owners/operator may not do the spar cap
modification unless that person holds the proper mechanic
authorization. If, as of [effective date] (the effective date of AD
**-**-**), your airplane is over or within 50 hours of reaching the
4,000 hour TIS modification requirement, do the modification within
the next 50 hours TIS.
b. Before doing the modification, do an eddy-current inspection
following Snow Engineering Process Specification 197, page
1, revised June 4, 2002; pages 2 through 5, revised May 3, 2002,
unless already done following the applicable Snow Engineering
Service Letter 197 or 205, both revised March 26,
2001.
c. Your logbook entry must include the work done and the
inspection intervals that are upcoming, as follows:
``Following AD **-**-**, at XXXX {insert hours TIS of the
modification{time} hours TIS an eddy-current inspection has been
done. As of now, the safe life listed in the AD no longer applies to
this airplane. This airplane must be eddy-current inspected at
{insert the number of hours TIS at modification plus 1,600 hours
TIS{time} hours TIS.
5. For all S/Ns, upon accumulating 1,600 hours TIS after
modification, inspect the left-hand and right-hand outboard two
lower spar cap bolt holes following Snow Engineering Process
Specification 197, page 1, revised June 4, 2002; pages 2
through 5, revised May 3, 2002.
6. Repeat the inspection at intervals of:
a. 800 hours TIS; or
b. 1,600 hours TIS if the outboard two lower spar cap bolt holes
have been cold worked following Snow Engineering Service Letter
234, dated May 18, 2004 (See Step 8).
c. Your logbook entry must include the work done and the post-
modification inspection intervals that are upcoming, as follows:
``This airplane must be eddy-current inspected at intervals not
to exceed {800/1,600, as applicable{time} hours TIS. The first of
these inspections is due at {insert the total number of hours TIS
the first of these inspections is due{time} hours TIS.''
d. If a crack is found at any time, before further flight you
must replace the lower spar caps, splice blocks, and wing attach
angles and hardware. You must also notify the FAA using the form in
Figure 1 of this AD.
7. Upon accumulating 8,000 hours TIS, before further flight you
must replace the lower spar caps, splice blocks, and wing attach
angles (P/N 20693-1), and associated hardware. No additional time
will be authorized for airplanes that are at or over 8,000 hours TIS
(see Step 9).
8. (OPTIONAL): If you decide to cold work your bolt holes
following Snow Engineering Service Letter 233 or
234, both dated May 18, 2002, at a TIS that does not
coincide with a scheduled inspection following this AD, then eddy-
current inspect at the time of cold working and then begin the
1,600/1,200 hour TIS inspection intervals (2 times the intervals
listed in Steps 2.a., 2.b., and 6.a. listed above).
9. (OPTIONAL): If you have modified your airplane in accordance
with Step 4 above before accumulating 4,000 hours TIS, then you may
continue to fly your airplane past (modification + 4,000 hours TIS)
provided you cut your inspection intervals in half. Make a logbook
entry following Step 6.c. above to reflect these reduced inspection
intervals. Upon accumulating 8,000 hours TIS, you must comply with
Step 7 above.
EXAMPLE: An AT-502B airplane had the two-part modification
installed at 3,000 hours TIS and the bolt holes have not been cold
worked.
The first inspection would occur at 4,600 hours TIS. From Step
5, this is modification plus 1,600 hours TIS.
Inspections would follow at 5,400 hours TIS, 6,200 hours TIS,
and 7,000 hours TIS. From Step 6.a. above, this is 800-hour TIS
inspection intervals.
Regarding the inspection at 7,000 hours TIS (modification plus
4,000 hours TIS), this relates to the 8,000-hour TIS inspection from
Step 7 above, which is modification plus 4,000 hours TIS, except in
this example the modification took place at 3,000 hours TIS instead
of 4,000 hours TIS as specified in Step 4 above.
This airplane may continue to fly if inspected again at 7,400
hours TIS and 7,800 hours TIS, which is 400-hour TIS inspection
intervals. This 400-hour TIS inspection interval corresponds to Step
9 where you cut your inspection interval from Step 6.a. in half.
Upon accumulating 8,000 hours TIS (this is the same as Step 7
above), you must replace the parts listed in Step 7.
For airplanes that have or have had Marburger Enterprise, Inc.
winglets installed following Supplemental Type Certificate (STC)
SA00490LA:
If you have removed the winglets, calculate new, reduced hours
for Steps 1, 4, 5, and 7, as applicable, based on the winglet usage
factor listed in Table 2 of paragraph (c)(4) and Appendix 2 of this
AD.
You may repetitively inspect at the same intervals listed in
Step 2 above provided that you do not re-install the winglets.
EXAMPLE: An AT-502 airplane, S/N 502-0200, had winglets
installed at 200 hours TIS and removed at 800 hours TIS.

The winglet usage factor is: 1.6
Calculate equivalent hours: 600 hours TIS with winglets X 1.6 = 960
hours TIS
Winglet usage penalty = 960 - 600 = 360
New Step 1 Pre-Modification Initial Inspection Time = 1,600 - 360 =
1,240 hours TIS
Retained Step 2 Pre-Modification Inspection Interval: Since the
winglets are removed, the Pre-Modification Inspection Interval
remains 800 hours TIS.
New Step 4 Modification time = 4,000 - 360 = 3,640 hours TIS
New Step 5 Post-Modification Initial Inspection time = 3,640 + 1,600
= 5,240 hours TIS.
Retained Step 6 Post-Modification Inspection interval: Since the
winglets are removed

[[Page 45467]]

the Post-Modification Inspection interval remains at 800/1,600 hours
TIS.
New Step 7 replacement time = 8,000 - 360= 7,640 hours TIS

Use the Retained Step 2 interval, the New Step 5 time, and the
Retained Step 6 interval to make appropriate logbook entries for the
pre- and post-modification intervals, using the format presented in
Steps 2.d., 4.c., and 6.c.
If you have not removed the winglets, then calculate new,
reduced hours for Step 1, 2, 4, 5, 6, and 7 above, as applicable,
based on the winglet usage factor listed in Table 2 of paragraph
(c)(4) of this AD and Appendix 2 of this AD.
Repetitively inspect at the appropriate interv

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