Airworthiness Directives; General Electric Company CF6-45 and CF6-50 Series Turbofan Engines, 77-80 [E7-25458]

Download as PDF Federal Register / Vol. 73, No. 1 / Wednesday, January 2, 2008 / Proposed Rules TABLE 1.—AFFECTED TAY 650–15 ENGINES BY SERIAL NUMBER—Continued Engine serial number 17521 17523 17539 17542 17556 17561 17562 17563 17580 17581 17612 17618 17635 17637 17645 17661 17686 17699 17701 17702 17736 17737 17738 17739 17741 17742 17808 Issued in Burlington, Massachusetts, on December 26, 2007. Peter A. White, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. E7–25457 Filed 12–31–07; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION mstockstill on PROD1PC66 with PROPOSALS Actions and Compliance (e) Unless already done, do the following actions. (1) Prior to accumulating 11,700 flight cycles (FC) since new, and thereafter at intervals not exceeding 11,700 FC of the engine, inspect the low pressure turbine discs stage 2 and stage 3 for corrosion in accordance with Rolls-Royce Deutschland Non-Modification Alert Service Bulletin TAY–72–A1524, Revision 1. (2) For engines that already exceed 11,700 FC on the effective date of this AD, perform the inspection within 90 days after the effective date of this AD. (3) When, during any of the inspections as required by paragraph (e)(1) of this directive, corrosion is found, replace the affected parts using the rejection criteria described in the 16:49 Dec 31, 2007 Other FAA AD Provisions (f) Alternative Methods of Compliance (AMOCs): The Manager, Engine Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Related Information (g) Refer to EASA Airworthiness Directive 2006–0288, dated September 15, 2006, and RRD Alert Service Bulletin TAY–72–A1524, Revision 1, dated September 1, 2006, for related information. (h) Contact Jason Yang, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: jason.yang@faa.gov; telephone (781) 238–7747; fax (781) 238–7199, for more information about this AD. Reason (d) Strip results from some of the engines listed in the applicability section of this directive revealed excessively corroded low pressure turbine discs stage 2 and stage 3. The corrosion is considered to be caused by the environment in which these engines are operated. Following a life assessment based on the strip findings it is concluded that inspections for corrosion attack are required. The action specified by this AD is intended to avoid a failure of a low pressure turbine disk stage 2 or stage 3 due to potential corrosion problems which could result in uncontained engine failure and damage to the airplane. We are proposing this AD to detect corrosion that could cause stage 2 or stage 3 disk of the low pressure turbine to fail and result in an uncontained failure of the engine. VerDate Aug<31>2005 Rolls-Royce TAY 650 Engine Manual—ETAY–3RR. Jkt 214001 Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2006–24145; Directorate Identifier 2006–NE–06–AD] RIN 2120–AA64 Airworthiness Directives; General Electric Company CF6–45 and CF6–50 Series Turbofan Engines Federal Aviation Administration (FAA), Department of Transportation (DOT). ACTION: Supplemental notice of proposed rulemaking (NPRM); reopening of comment period. AGENCY: SUMMARY: This supplemental NPRM revises an earlier proposed airworthiness directive (AD), applicable to certain General Electric Company (GE) CF6–45 and CF6–50 series turbofan engines. That proposed AD would have required inspecting and reworking certain forward and aft centerbodies of the long fixed core exhaust nozzle (LFCEN) assembly. That proposed AD resulted from reports of separation of the forward and aft centerbodies of the LFCEN assembly due to high-imbalance engine conditions. This supplemental NPRM revises the proposed AD to add one engine model, and by replacing the LFCEN instead of repairing the centerbodies. This proposed AD results from the engine manufacturer issuing PO 00000 Frm 00005 Fmt 4702 Sfmt 4702 77 new service information. We are proposing this AD to prevent the forward and aft centerbody of the LFCEN assembly from separating, leading to additional damage to the airplane. DATES: We must receive any comments on this proposed AD by February 19, 2008. ADDRESSES: Use one of the following addresses to comment on this proposed AD. • Federal eRulemaking Portal: Go to https://www.regulations.gov and follow the instructions for sending your comments electronically. • Mail: Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12–140, Washington, DC 20590–0001. • Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. • Fax: (202) 493–2251. You can get the service information identified in this proposed AD from General Electric Company via GEAviation, Attn: Distributions, 111 Merchant St., Room 230, Cincinnati, Ohio 45246, telephone (513) 552–3272; fax (513) 552–3329. FOR FURTHER INFORMATION CONTACT: Robert Green, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: robert.green@faa.gov; telephone (781) 238–7754; fax (781) 238–7199. SUPPLEMENTARY INFORMATION: Comments Invited We invite you to send us any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include ‘‘Docket No. FAA– 2006–24145; Directorate Identifier 2006–NE–06–AD’’ in the subject line 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:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of the Web site, anyone can find and read the comments in any of our dockets, E:\FR\FM\02JAP1.SGM 02JAP1 78 Federal Register / Vol. 73, No. 1 / Wednesday, January 2, 2008 / Proposed Rules Comments Examining the AD Docket You may examine the AD docket on the Internet at https:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647–5527) is the same as the Mail address provided in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. mstockstill on PROD1PC66 with PROPOSALS including, if provided, the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT’s complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477–78). One commenter asks us to provide continued-operation serviceability limits in terms of flight cycles or flight hours and a maximum allowable crack length to allow operators to schedule removing and installing the LFCEN if a crack is found during an in-service, line station inspection. The commenter states that specifying continuedoperation serviceability limits will preclude unscheduled maintenance and costly downtime. We don’t agree that we should provide continued-operation serviceability limits in this proposed AD. An operator’s approved maintenance plan should define the continued-operation serviceability criteria. We didn’t change the proposed NPRM. Discussion On March 27, 2006, we issued a proposal to amend part 39 of the Code of Federal Regulations (14 CFR part 39) to add an AD, applicable to GE CF6–45 and –50 series turbofan engines. The proposed AD published as an NPRM in the Federal Register on March 31, 2006 (71 FR 16246). That NPRM proposed to require reworking the forward and aft centerbodies to add doublers, larger nuts and bolts, and higher strength corrosion resistant nut plates. That rework would be required the next time the forward centerbody and aft centerbody are removed from the engine after the effective date of this proposed AD. Since we issued that NPRM, we determined that the referenced GE rework instructions in GE service bulletin (SB) No. CF6–50 S/B 78–0242 were incompatible with the existing repair in the Engine Manual. GE subsequently superseded SB No. CF6– 50 S/B 78–0242 with SB No. GE CF6– 50 S/B 78–0244, which corrected the error. We also found that we didn’t specify the CF6–50A model engine in the Applicability of the proposed AD. We added the CF6–50A engine model to the Applicability of the proposed AD. Because we expanded the population of affected engines by adding the CF6–50A model, this supplemental NPRM reopens the comment period to include the CF6–50A engine model and references the new rework instructions. This condition, if not corrected, could result in the forward and aft centerbody of the LFCEN assembly separating, leading to additional damage to the airplane. VerDate Aug<31>2005 16:49 Dec 31, 2007 Jkt 214001 We provided the public the opportunity to participate in the development of this proposed AD. We have considered the comments received. Request for Continued Operational Serviceability Limits Request To Remove Requirement To Modify LFCEN to SB CF6–50 S/B 78– 0242 Atlas Air asks us to remove the requirement to use GE SB No. CF6–50 S/B 78–0242 to modify the LFCEN. Atlas Air believes that they can maintain an equivalent level of safety by modifying the forward and aft centerbody as specified in GE SB No. CF6–50 S/B 78–0216, Revision 1, dated October 23, 1987, and adhering to the torque requirements for the aft centerbody bolts as specified in GE SB No. CF6–50 S/B 78–0241, dated January 7, 2003. Atlas Air notes that after the OEM introduced SB No. CF6–50 S/B 78–0216 Revision 1, which instituted the Sixteen-bolt Forward and Aft Centerbody Configuration, 22 events were recorded. But, the OEM has not provided data as to how many of the 22 events occurred on centerbodies modified using only SB No. CF6–50 S/ B 78–0216, Revision 1. Atlas Air also notes that no events of separations of the forward and aft centerbody have occurred since the OEM introduced the increased torque requirements for the forward-to-aft centerbody joint bolts. We don’t agree. Analysis and component tests following release of GE SB No. CF6–50 S/B 78–0216 and SB No. CF6–50 S/B 78–0241 identified several other design shortcomings at fan bladeout imbalance loads. Improvements released through GE SB No. CF6–50 S/ B 78–0242 (and subsequently GE SB No. CF6–50 S/B 78–0244) addressed those design concerns. GE SB No. CF6–50 S/ PO 00000 Frm 00006 Fmt 4702 Sfmt 4702 B 78–0216 and SB No. CF6–50 S/B 78– 0241 don’t address fully the identified LFCEN forward-to-aft centerbody separation issues. Incorporating the modifications defined in GE SB No. CF6–50 S/B 78–0244 would preclude the need to require repetitive on-wing inspections. We didn’t change the proposed NPRM. Request To Change the Compliance Time Atlas Air proposes that we change the compliance time for modifying the forward and aft centerbody as specified in GE SB No. CF6–50 S/B 78–0242 from ‘‘the next time the forward and aft centerbody is removed from the engine’’ to ‘‘each time the forward or aft centerbody is removed and routed for repair.’’ Atlas Air states that the requirement to modify the forward and aft centerbody each time they remove an engine will increase the number of spare centerbodies needed. Atlas Air calculates the need for an additional five forward and aft centerbodies at an additional cost of $696,960. We don’t agree. Incorporating the GE SB No. CF6–50 S/B 78–0244 modifications when the centerbodies are repaired for unserviceable conditions would extend the compliance period unreasonably. The intent of the original compliance recommendation was to align and execute the modifications with engine refurbishments. The intent of the hard-time compliance period recommendation in this superseding NPRM is to complete the modifications within the same time period as the original engine removal recommendations. We didn’t change the proposed NPRM. Request To Change the Costs of Compliance Atlas Air also believes that we underestimated the cost impact of the proposed rule. Atlas Air uses third party labor and does not agree that the $80 per hour rate is the true industry average. Atlas Air also observes that we do include the cost of spare centerbodies that would be required to support the compliance requirements of this rule. Atlas Air used a figure of $100 per hour in their subsequent cost calculation and included required spare parts in their projected compliance costs. We don’t agree. We use the average labor rate established by the Office of Aviation Policy, Plans, and Management Analysis (APO) for estimating the projected cost impact of ADs. We don’t project additional costs associated with spare parts, because ADs address an unsafe condition in a product (in this case an engine) and the unsafe E:\FR\FM\02JAP1.SGM 02JAP1 Federal Register / Vol. 73, No. 1 / Wednesday, January 2, 2008 / Proposed Rules mstockstill on PROD1PC66 with PROPOSALS condition doesn’t exist until the spare parts are on the engine and the engine is in service. However, GE made corrections to SB No. CF6–50 S/B 78–0244, dated July 30, 2007, that included a revision of the projected labor work-hours to complete the modification. GE SB No. CF6–50 S/ B 78–0242, dated September 26, 2005, cited 22 work-hours to complete the modification. That was for one centerbody half. The total labor workhours to modify both centerbodies are 44 work-hours, which is cited in GE SB No. CF6–50 S/B 78–0244, dated July 30, 2007. We changed the Costs of Compliance section in the AD to reflect 44 work-hours per product. Request To Change the Compliance Times One commenter, FedEx, suggests a hard-time limit of 30 months after the effective date of the proposed AD to modify all LFCEN assemblies in accordance with GE SB No. CF6–50 S/ B 78–0242 (subsequently superseded by GE SB No. CF6–50 S/B 78–0244) instead of when the centerbodies are removed when an engine is taken off wing. FedEx believes that the requirement to perform the modification at the next engine change will create an undue burden on line maintenance operations and prolong completing the modifications. Spare engines ship without the LFCEN assembly which is typically transferred to the new engine from the old engine at engine replacement. FedEx states that, under the requirements in the current NPRM, operators will have to pre-position spare LFCEN assemblies with spare engines to remote outstations. This requirement and additional logistics will unduly increase operator spare cost and cost of out of service aircraft. FedEx contends that a hard-time compliance limit will relieve operations from the increased logistics and spare costs and accelerate completion of the modification. With the current requirement to complete the modification when the LFCEN is removed from the engine, accomplishment could take more than 4 years. A fixed time of 30 months, versus at next engine removal, would allow operators to control the modifications at heavy maintenance checks and expedite completion of the modifications directed by this proposed AD. We partially agree. We agree that a hard-time completion recommendation works better than an engine removal basis for the centerbody rework. We don’t agree that 30 months is the appropriated compliance period. We revised the proposed NPRM accordingly, citing a 42 month VerDate Aug<31>2005 16:49 Dec 31, 2007 Jkt 214001 compliance period. The 42 month limit is based on the CF6–50 average time-onwing performance and annual utilization. Request for a Grace Period Two commenters, the Air Transport Association and Northwest Airlines, request a grace period of 12 months after the effective date of the proposed AD to acquire and modify spare forward and aft centerbodies. The commenters state that the available number of modified spare centerbody assemblies is extremely low and the grace period for provisioning would avoid extended aircraft-on-ground situations. We don’t agree that a grace period is necessary, given our response to the previous comment. We didn’t change the proposed NPRM. Differences Between the Service Bulletin and the Component Maintenance Manual Repair Procedure Two commenters identified issues with incorporating GE SB No. CF6–50 S/B 78–0242, dated September 26, 2005. One commenter, Air Nippon Airways, requests that the GE SB recommend the CMM 78–11–02 repair modification for the forward centerbodies and that they be reflected in the FAA AD. Air Nippon Airways notes that the fastener locations on the forward centerbody aft doubler and aft doubler splices defined by GE SB No. CF6–50 S/B 78–0242 and GE Repair Document (RD) 250–206–S1 are different than those defined by the corresponding Component Maintenance Manual (CMM) repair. The aft doubler and aft doubler splices could not be installed on forward centerbodies that had been repaired in accordance with the CMM 78–11–02 Repair 001. In addition, the band doubler specified by the GE SB was already required with the CMM repair. We agree. ANA is correct in their statement that the GE SB No. CF6–50 S/B 78–0242, dated September 26, 2005, and CMM instructions were incompatible. GE subsequently superseded SB No. CF6–50 S/B 78– 0242, dated September 26, 2005, with GE SB No. CF6–50 S/B 78–0244, dated July 30, 2007, which corrects the error by referencing the pre-existing repair for modifying the forward centerbody. We changed the proposed NPRM references to reflect the corrected service bulletin instructions. One commenter, Airbus, reports that since release of the NPRM, docket No. FAA–2007–24145 (Directorate identifier 2006–NE–06–AD), operators report having difficulties implementing GE SB No. CF6–50 S/B 78–0242, dated September 26, 2005, due to a parallel spot-weld repair in Engine Manual PO 00000 Frm 00007 Fmt 4702 Sfmt 4702 79 Repair 78–11–02–300–001. That repair incorporates an aft joint doubler that interferes with the repair required by GE SB No. CF6–50 S/B 78–0242, dated September 26, 2005. Airbus notes that GE was revising SB No. CF6–50 S/B 78– 0242, dated September 26, 2005, to define the proper doublers, update the repair, and contact the service bulletin. Airbus asks if we were informed of this situation and whether it is planned to postpone or review the current proposed rulemaking. We were aware of the identified issues with the original service bulletin recommendations and that GE was revising SB No. CF6–50 S/B 78–0242, dated September 26, 2005. This proposed AD references the revised modifications released by GE SB No. CF6–50 S/B 78–0244, dated July 30, 2007. This proposed AD addresses those accomplishment instruction changes, and address the compliance recommendations proposed by FedEx, the ATA, and Northwest Airlines. We didn’t change the proposed NPRM. Relevant Service Information We have reviewed and approved the technical contents of GE SB No. CF6–50 S/B 78–0244, dated July 30, 2007, that identifies disassembly, inspection, rework, and reassembly procedures for the forward and aft centerbodies. Differences Between the Proposed AD and the Service Information GE SB No. CF6–50 S/B 78–0244, dated July 30, 2007 requires reworking the forward and aft centerbodies when the centerbodies are removed from the engine. This proposed NPRM requires replacing the centerbodies with centerbodies that were modified using the Accomplishment Instructions, Section 3, of GE SB No. CF6–50 S/B 78– 0244, dated July 30, 2007, within 42 months of the effective date of the proposed AD. FAA’s Determination and Requirements of the Proposed AD We evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other products of this same type design. We are proposing this AD, which will require replacing certain forward and aft centerbodies with new or modified forward and aft centerbodies. These replacements are required within 42 months after the effective date of this proposed AD. The proposed AD would require you to use the service information described previously to modify the forward and aft centerbodies before assembling them to the engine. E:\FR\FM\02JAP1.SGM 02JAP1 80 Federal Register / Vol. 73, No. 1 / Wednesday, January 2, 2008 / Proposed Rules Costs of Compliance List of Subjects in 14 CFR Part 39 We estimate that this proposed AD would affect 379 GE CF6–45 and CF6– 50 series turbofan engines installed on airplanes of U.S. registry. We also estimate that it would take about 44 work hours per engine to perform the proposed actions, and that the average labor rate is $80 per work hour. Required parts would cost about $11,000 per engine. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $2,802,360. Air transportation, Aircraft, Aviation safety, Safety. 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. mstockstill on PROD1PC66 with PROPOSALS 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. Would 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. See the ADDRESSES section for a location to examine the regulatory evaluation. VerDate Aug<31>2005 16:49 Dec 31, 2007 Jkt 214001 The Proposed Amendment 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. § 39.13 [Amended] 2. The FAA amends § 39.13 by adding the following new airworthiness directive: General Electric Company: Docket No. FAA– 2006–24145; Directorate Identifier 2006– NE–06–AD. Alternative Methods of Compliance (g) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19. Related Information (h) Contact Robert Green, Aerospace Engineer, Engine Certification Office, FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803; e-mail: robert.green@faa.gov; telephone (781) 238–7754; fax (781) 238– 7199, for more information about this AD. Issued in Burlington, Massachusetts, on December 17, 2007. Peter A. White, Assistant Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. E7–25458 Filed 12–31–07; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Comments Due Date (a) The Federal Aviation Administration (FAA) must receive comments on this airworthiness directive (AD) action by February 19, 2008. Federal Aviation Administration Affected ADs (b) None. RIN 2120–AA64 Applicability (c) This AD applies to General Electric Company (GE) CF6–45A, CF6–45A2, CF6– 50A, CF6–50C, CF6–50CA, CF6–50C1, CF6– 50C2, CF6–50C2B, CF6–50C2D, CF6–50E, CF6–50E1, CF6–50E2, and CF6–50E2B series turbofan engines with long fixed core exhaust nozzle (LFCEN) assembly forward centerbody, part number (P/N) 1313M55G01 or G02, P/N 9076M28G09 or G10, and aft centerbody P/N 1313M56G01 or 9076M46G05, installed. These engines are installed on, but not limited to, Airbus A300 series, Boeing 747 series, McDonnell Douglas DC–10 series, and DC–10–30F (KC–10A, KDC–10) airplanes. Unsafe Condition (d) This AD results from reports of separation of LFCEN assembly forward and aft centerbodies, due to high imbalance engine conditions. We are issuing this AD to prevent the forward and aft centerbody of the LFCEN assembly from separating, leading to additional damage to the airplane. Compliance (e) You are responsible for having the actions required by this AD performed within 42 months after the effective date of this AD, unless the actions have already been done. (f) Replace the forward centerbody, P/N 1313M55G01 or G02, P/N 9076M28G09 or G10, and aft centerbody, P/N 1313M56G01 or 9076M46G05 with a forward and aft centerbody that have been modified using with the Accomplishment Instructions, Section 3, of GE service bulletin No. CF6–50 S/B 78–0244, dated July 30, 2007. PO 00000 Frm 00008 Fmt 4702 Sfmt 4702 14 CFR Part 39 [Docket No. FAA–2007–0372; Directorate Identifier 2007–NM–164–AD] Airworthiness Directives; Construcciones Aeronauticas, S.A., (CASA) Model C–212 Airplanes Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). AGENCY: SUMMARY: We propose to adopt a new airworthiness directive (AD) for the products listed above that would supersede an existing AD. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: On 23 November 2006, Emergency Airworthiness Directive (EAD) Nr. (number) 2006–0351–E was published requiring an inspection to be performed on C–212 aeroplanes having been used for Maritime Patrol or other similar low altitude operations, due to the fact that, after initial examination of the evidences of a recent C– 212 Maritime Patrol aircraft accident, cracks had been found in the centre wing lower skin at STA Y=1030. At the time of the accident, the aircraft had accumulated 17,000 flight hours and 7,300 flight cycles. The cracks were suspected to be caused by fatigue. A more detailed examination in the laboratory, led to think that the initiation of the fatigue cracks was produced by fretting, and EAD 2006–0365–E, superseding EAD E:\FR\FM\02JAP1.SGM 02JAP1

Agencies

[Federal Register Volume 73, Number 1 (Wednesday, January 2, 2008)]
[Proposed Rules]
[Pages 77-80]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-25458]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24145; Directorate Identifier 2006-NE-06-AD]
RIN 2120-AA64


Airworthiness Directives; General Electric Company CF6-45 and 
CF6-50 Series Turbofan Engines

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

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

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

SUMMARY: This supplemental NPRM revises an earlier proposed 
airworthiness directive (AD), applicable to certain General Electric 
Company (GE) CF6-45 and CF6-50 series turbofan engines. That proposed 
AD would have required inspecting and reworking certain forward and aft 
centerbodies of the long fixed core exhaust nozzle (LFCEN) assembly. 
That proposed AD resulted from reports of separation of the forward and 
aft centerbodies of the LFCEN assembly due to high-imbalance engine 
conditions. This supplemental NPRM revises the proposed AD to add one 
engine model, and by replacing the LFCEN instead of repairing the 
centerbodies. This proposed AD results from the engine manufacturer 
issuing new service information. We are proposing this AD to prevent 
the forward and aft centerbody of the LFCEN assembly from separating, 
leading to additional damage to the airplane.

DATES: We must receive any comments on this proposed AD by February 19, 
2008.

ADDRESSES: Use one of the following addresses to comment on this 
proposed AD.
     Federal eRulemaking Portal: Go to https://
www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility, U.S. Department of 
Transportation, 1200 New Jersey Avenue, SE., West Building Ground 
Floor, Room W12-140, Washington, DC 20590-0001.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.
    You can get the service information identified in this proposed AD 
from General Electric Company via GE-Aviation, Attn: Distributions, 111 
Merchant St., Room 230, Cincinnati, Ohio 45246, telephone (513) 552-
3272; fax (513) 552-3329.

FOR FURTHER INFORMATION CONTACT: Robert Green, Aerospace Engineer, 
Engine Certification Office, FAA, Engine & Propeller Directorate, 12 
New England Executive Park, Burlington, MA 01803; e-mail: 
robert.green@faa.gov; telephone (781) 238-7754; fax (781) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send us any written relevant data, views, or 
arguments regarding this proposal. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2006-24145; 
Directorate Identifier 2006-NE-06-AD'' in the subject line 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://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact 
with FAA personnel concerning this proposed AD. Using the search 
function of the Web site, anyone can find and read the comments in any 
of our dockets,

[[Page 78]]

including, if provided, the name of the individual who sent the comment 
(or signed the comment on behalf of an association, business, labor 
union, etc.). You may review the DOT's complete Privacy Act Statement 
in the Federal Register published on April 11, 2000 (65 FR 19477-78).

Examining the AD Docket

    You may examine the AD docket on the Internet at https://
www.regulations.gov; or in person at the Docket Operations office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Operations office (telephone (800) 647-5527) is 
the same as the Mail address provided in the ADDRESSES section. 
Comments will be available in the AD docket shortly after receipt.

Discussion

    On March 27, 2006, we issued a proposal to amend part 39 of the 
Code of Federal Regulations (14 CFR part 39) to add an AD, applicable 
to GE CF6-45 and -50 series turbofan engines. The proposed AD published 
as an NPRM in the Federal Register on March 31, 2006 (71 FR 16246). 
That NPRM proposed to require reworking the forward and aft 
centerbodies to add doublers, larger nuts and bolts, and higher 
strength corrosion resistant nut plates. That rework would be required 
the next time the forward centerbody and aft centerbody are removed 
from the engine after the effective date of this proposed AD.
    Since we issued that NPRM, we determined that the referenced GE 
rework instructions in GE service bulletin (SB) No. CF6-50 S/B 78-0242 
were incompatible with the existing repair in the Engine Manual. GE 
subsequently superseded SB No. CF6-50 S/B 78-0242 with SB No. GE CF6-50 
S/B 78-0244, which corrected the error. We also found that we didn't 
specify the CF6-50A model engine in the Applicability of the proposed 
AD. We added the CF6-50A engine model to the Applicability of the 
proposed AD. Because we expanded the population of affected engines by 
adding the CF6-50A model, this supplemental NPRM reopens the comment 
period to include the CF6-50A engine model and references the new 
rework instructions.
    This condition, if not corrected, could result in the forward and 
aft centerbody of the LFCEN assembly separating, leading to additional 
damage to the airplane.

Comments

    We provided the public the opportunity to participate in the 
development of this proposed AD. We have considered the comments 
received.

Request for Continued Operational Serviceability Limits

    One commenter asks us to provide continued-operation serviceability 
limits in terms of flight cycles or flight hours and a maximum 
allowable crack length to allow operators to schedule removing and 
installing the LFCEN if a crack is found during an in-service, line 
station inspection. The commenter states that specifying continued-
operation serviceability limits will preclude unscheduled maintenance 
and costly downtime. We don't agree that we should provide continued-
operation serviceability limits in this proposed AD. An operator's 
approved maintenance plan should define the continued-operation 
serviceability criteria. We didn't change the proposed NPRM.

Request To Remove Requirement To Modify LFCEN to SB CF6-50 S/B 78-0242

    Atlas Air asks us to remove the requirement to use GE SB No. CF6-50 
S/B 78-0242 to modify the LFCEN. Atlas Air believes that they can 
maintain an equivalent level of safety by modifying the forward and aft 
centerbody as specified in GE SB No. CF6-50 S/B 78-0216, Revision 1, 
dated October 23, 1987, and adhering to the torque requirements for the 
aft centerbody bolts as specified in GE SB No. CF6-50 S/B 78-0241, 
dated January 7, 2003. Atlas Air notes that after the OEM introduced SB 
No. CF6-50 S/B 78-0216 Revision 1, which instituted the Sixteen-bolt 
Forward and Aft Centerbody Configuration, 22 events were recorded. But, 
the OEM has not provided data as to how many of the 22 events occurred 
on centerbodies modified using only SB No. CF6-50 S/B 78-0216, Revision 
1. Atlas Air also notes that no events of separations of the forward 
and aft centerbody have occurred since the OEM introduced the increased 
torque requirements for the forward-to-aft centerbody joint bolts.
    We don't agree. Analysis and component tests following release of 
GE SB No. CF6-50 S/B 78-0216 and SB No. CF6-50 S/B 78-0241 identified 
several other design shortcomings at fan blade-out imbalance loads. 
Improvements released through GE SB No. CF6-50 S/B 78-0242 (and 
subsequently GE SB No. CF6-50 S/B 78-0244) addressed those design 
concerns. GE SB No. CF6-50 S/B 78-0216 and SB No. CF6-50 S/B 78-0241 
don't address fully the identified LFCEN forward-to-aft centerbody 
separation issues. Incorporating the modifications defined in GE SB No. 
CF6-50 S/B 78-0244 would preclude the need to require repetitive on-
wing inspections. We didn't change the proposed NPRM.

Request To Change the Compliance Time

    Atlas Air proposes that we change the compliance time for modifying 
the forward and aft centerbody as specified in GE SB No. CF6-50 S/B 78-
0242 from ``the next time the forward and aft centerbody is removed 
from the engine'' to ``each time the forward or aft centerbody is 
removed and routed for repair.'' Atlas Air states that the requirement 
to modify the forward and aft centerbody each time they remove an 
engine will increase the number of spare centerbodies needed. Atlas Air 
calculates the need for an additional five forward and aft centerbodies 
at an additional cost of $696,960.
    We don't agree. Incorporating the GE SB No. CF6-50 S/B 78-0244 
modifications when the centerbodies are repaired for unserviceable 
conditions would extend the compliance period unreasonably. The intent 
of the original compliance recommendation was to align and execute the 
modifications with engine refurbishments. The intent of the hard-time 
compliance period recommendation in this superseding NPRM is to 
complete the modifications within the same time period as the original 
engine removal recommendations. We didn't change the proposed NPRM.

Request To Change the Costs of Compliance

    Atlas Air also believes that we underestimated the cost impact of 
the proposed rule. Atlas Air uses third party labor and does not agree 
that the $80 per hour rate is the true industry average. Atlas Air also 
observes that we do include the cost of spare centerbodies that would 
be required to support the compliance requirements of this rule. Atlas 
Air used a figure of $100 per hour in their subsequent cost calculation 
and included required spare parts in their projected compliance costs.
    We don't agree. We use the average labor rate established by the 
Office of Aviation Policy, Plans, and Management Analysis (APO) for 
estimating the projected cost impact of ADs. We don't project 
additional costs associated with spare parts, because ADs address an 
unsafe condition in a product (in this case an engine) and the unsafe

[[Page 79]]

condition doesn't exist until the spare parts are on the engine and the 
engine is in service.
    However, GE made corrections to SB No. CF6-50 S/B 78-0244, dated 
July 30, 2007, that included a revision of the projected labor work-
hours to complete the modification. GE SB No. CF6-50 S/B 78-0242, dated 
September 26, 2005, cited 22 work-hours to complete the modification. 
That was for one centerbody half. The total labor work-hours to modify 
both centerbodies are 44 work-hours, which is cited in GE SB No. CF6-50 
S/B 78-0244, dated July 30, 2007. We changed the Costs of Compliance 
section in the AD to reflect 44 work-hours per product.

Request To Change the Compliance Times

    One commenter, FedEx, suggests a hard-time limit of 30 months after 
the effective date of the proposed AD to modify all LFCEN assemblies in 
accordance with GE SB No. CF6-50 S/B 78-0242 (subsequently superseded 
by GE SB No. CF6-50 S/B 78-0244) instead of when the centerbodies are 
removed when an engine is taken off wing. FedEx believes that the 
requirement to perform the modification at the next engine change will 
create an undue burden on line maintenance operations and prolong 
completing the modifications. Spare engines ship without the LFCEN 
assembly which is typically transferred to the new engine from the old 
engine at engine replacement. FedEx states that, under the requirements 
in the current NPRM, operators will have to pre-position spare LFCEN 
assemblies with spare engines to remote outstations. This requirement 
and additional logistics will unduly increase operator spare cost and 
cost of out of service aircraft. FedEx contends that a hard-time 
compliance limit will relieve operations from the increased logistics 
and spare costs and accelerate completion of the modification. With the 
current requirement to complete the modification when the LFCEN is 
removed from the engine, accomplishment could take more than 4 years. A 
fixed time of 30 months, versus at next engine removal, would allow 
operators to control the modifications at heavy maintenance checks and 
expedite completion of the modifications directed by this proposed AD.
    We partially agree. We agree that a hard-time completion 
recommendation works better than an engine removal basis for the 
centerbody rework. We don't agree that 30 months is the appropriated 
compliance period. We revised the proposed NPRM accordingly, citing a 
42 month compliance period. The 42 month limit is based on the CF6-50 
average time-on-wing performance and annual utilization.

Request for a Grace Period

    Two commenters, the Air Transport Association and Northwest 
Airlines, request a grace period of 12 months after the effective date 
of the proposed AD to acquire and modify spare forward and aft 
centerbodies. The commenters state that the available number of 
modified spare centerbody assemblies is extremely low and the grace 
period for provisioning would avoid extended aircraft-on-ground 
situations. We don't agree that a grace period is necessary, given our 
response to the previous comment. We didn't change the proposed NPRM.

Differences Between the Service Bulletin and the Component Maintenance 
Manual Repair Procedure

    Two commenters identified issues with incorporating GE SB No. CF6-
50 S/B 78-0242, dated September 26, 2005.
    One commenter, Air Nippon Airways, requests that the GE SB 
recommend the CMM 78-11-02 repair modification for the forward 
centerbodies and that they be reflected in the FAA AD. Air Nippon 
Airways notes that the fastener locations on the forward centerbody aft 
doubler and aft doubler splices defined by GE SB No. CF6-50 S/B 78-0242 
and GE Repair Document (RD) 250-206-S1 are different than those defined 
by the corresponding Component Maintenance Manual (CMM) repair. The aft 
doubler and aft doubler splices could not be installed on forward 
centerbodies that had been repaired in accordance with the CMM 78-11-02 
Repair 001. In addition, the band doubler specified by the GE SB was 
already required with the CMM repair. We agree. ANA is correct in their 
statement that the GE SB No. CF6-50 S/B 78-0242, dated September 26, 
2005, and CMM instructions were incompatible. GE subsequently 
superseded SB No. CF6-50 S/B 78-0242, dated September 26, 2005, with GE 
SB No. CF6-50 S/B 78-0244, dated July 30, 2007, which corrects the 
error by referencing the pre-existing repair for modifying the forward 
centerbody. We changed the proposed NPRM references to reflect the 
corrected service bulletin instructions.
    One commenter, Airbus, reports that since release of the NPRM, 
docket No. FAA-2007-24145 (Directorate identifier 2006-NE-06-AD), 
operators report having difficulties implementing GE SB No. CF6-50 S/B 
78-0242, dated September 26, 2005, due to a parallel spot-weld repair 
in Engine Manual Repair 78-11-02-300-001. That repair incorporates an 
aft joint doubler that interferes with the repair required by GE SB No. 
CF6-50 S/B 78-0242, dated September 26, 2005. Airbus notes that GE was 
revising SB No. CF6-50 S/B 78-0242, dated September 26, 2005, to define 
the proper doublers, update the repair, and contact the service 
bulletin. Airbus asks if we were informed of this situation and whether 
it is planned to postpone or review the current proposed rulemaking.
    We were aware of the identified issues with the original service 
bulletin recommendations and that GE was revising SB No. CF6-50 S/B 78-
0242, dated September 26, 2005. This proposed AD references the revised 
modifications released by GE SB No. CF6-50 S/B 78-0244, dated July 30, 
2007. This proposed AD addresses those accomplishment instruction 
changes, and address the compliance recommendations proposed by FedEx, 
the ATA, and Northwest Airlines. We didn't change the proposed NPRM.

Relevant Service Information

    We have reviewed and approved the technical contents of GE SB No. 
CF6-50 S/B 78-0244, dated July 30, 2007, that identifies disassembly, 
inspection, rework, and reassembly procedures for the forward and aft 
centerbodies.

Differences Between the Proposed AD and the Service Information

    GE SB No. CF6-50 S/B 78-0244, dated July 30, 2007 requires 
reworking the forward and aft centerbodies when the centerbodies are 
removed from the engine. This proposed NPRM requires replacing the 
centerbodies with centerbodies that were modified using the 
Accomplishment Instructions, Section 3, of GE SB No. CF6-50 S/B 78-
0244, dated July 30, 2007, within 42 months of the effective date of 
the proposed AD.

FAA's Determination and Requirements of the Proposed AD

    We evaluated all pertinent information and identified an unsafe 
condition that is likely to exist or develop on other products of this 
same type design. We are proposing this AD, which will require 
replacing certain forward and aft centerbodies with new or modified 
forward and aft centerbodies. These replacements are required within 42 
months after the effective date of this proposed AD. The proposed AD 
would require you to use the service information described previously 
to modify the forward and aft centerbodies before assembling them to 
the engine.

[[Page 80]]

Costs of Compliance

    We estimate that this proposed AD would affect 379 GE CF6-45 and 
CF6-50 series turbofan engines installed on airplanes of U.S. registry. 
We also estimate that it would take about 44 work hours per engine to 
perform the proposed actions, and that the average labor rate is $80 
per work hour. Required parts would cost about $11,000 per engine. 
Based on these figures, we estimate the total cost of the proposed AD 
to U.S. operators to be $2,802,360.

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. Would 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. See the ADDRESSES section for a location 
to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    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. The FAA amends Sec.  39.13 by adding the following new 
airworthiness directive:

General Electric Company: Docket No. FAA-2006-24145; Directorate 
Identifier 2006-NE-06-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this airworthiness directive (AD) action by February 19, 
2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to General Electric Company (GE) CF6-45A, 
CF6-45A2, CF6-50A, CF6-50C, CF6-50CA, CF6-50C1, CF6-50C2, CF6-50C2B, 
CF6-50C2D, CF6-50E, CF6-50E1, CF6-50E2, and CF6-50E2B series 
turbofan engines with long fixed core exhaust nozzle (LFCEN) 
assembly forward centerbody, part number (P/N) 1313M55G01 or G02, P/
N 9076M28G09 or G10, and aft centerbody P/N 1313M56G01 or 
9076M46G05, installed. These engines are installed on, but not 
limited to, Airbus A300 series, Boeing 747 series, McDonnell Douglas 
DC-10 series, and DC-10-30F (KC-10A, KDC-10) airplanes.

Unsafe Condition

    (d) This AD results from reports of separation of LFCEN assembly 
forward and aft centerbodies, due to high imbalance engine 
conditions. We are issuing this AD to prevent the forward and aft 
centerbody of the LFCEN assembly from separating, leading to 
additional damage to the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within 42 months after the effective date of this AD, 
unless the actions have already been done.
    (f) Replace the forward centerbody, P/N 1313M55G01 or G02, P/N 
9076M28G09 or G10, and aft centerbody, P/N 1313M56G01 or 9076M46G05 
with a forward and aft centerbody that have been modified using with 
the Accomplishment Instructions, Section 3, of GE service bulletin 
No. CF6-50 S/B 78-0244, dated July 30, 2007.

Alternative Methods of Compliance

    (g) The Manager, Engine Certification Office, has the authority 
to approve alternative methods of compliance for this AD if 
requested using the procedures found in 14 CFR 39.19.

Related Information

    (h) Contact Robert Green, Aerospace Engineer, Engine 
Certification Office, FAA, Engine & Propeller Directorate, 12 New 
England Executive Park, Burlington, MA 01803; e-mail: 
robert.green@faa.gov; telephone (781) 238-7754; fax (781) 238-7199, 
for more information about this AD.

    Issued in Burlington, Massachusetts, on December 17, 2007.
Peter A. White,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. E7-25458 Filed 12-31-07; 8:45 am]
BILLING CODE 4910-13-P

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