Airworthiness Directives; Boeing Model 747 Airplanes, 5770-5773 [E8-1704]

Download as PDF 5770 Federal Register / Vol. 73, No. 21 / Thursday, January 31, 2008 / Proposed Rules Boeing: Docket No. FAA–2008–0107; Directorate Identifier 2007–NM–087–AD. Comments Due Date (a) We must receive comments by March 17, 2008. Affected ADs (b) None. Applicability (c) This AD applies to Boeing Model 747– 100, 747–100B, 747–100B SUD, 747–200B, 747–200C, 747–200F, 747–300, 747–400, 747–400D, 747–400F, 747SP, and 747SR series airplanes, certificated in any category; as identified in Boeing Service Bulletin 747– 53A2563, Revision 2, dated January 3, 2008. Unsafe Condition (d) This AD results from reports of scribe lines found at lap joints and butt joints, around external doublers and antennas, and at locations where external decals had been cut. We are issuing this AD to detect and correct scribe lines, which can develop into fatigue cracks in the skin and cause sudden decompression of the airplane. Compliance (e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Inspection (f) At the applicable times specified in paragraph 1.E., ‘‘Compliance,’’ of Boeing Service Bulletin 747–53A2563, Revision 2, dated January 3, 2008, except as provided in paragraph (g) of this AD, do detailed exploratory inspections for scribe lines of affected lap and butt splices, wing-to-body fairing locations, and external repair and cutout reinforcement areas, and do all applicable related investigative and corrective actions, by accomplishing all actions specified in the Accomplishment Instructions of the service bulletin, except as provided by paragraph (h) of this AD. Note 1: The inspection exemptions noted in paragraph 1.E. of Boeing Service Bulletin 747–53A2563, Revision 2, dated January 3, 2008, apply to this AD. sroberts on PROD1PC70 with PROPOSALS Exceptions to Service Bulletin Specifications (g) Where Boeing Service Bulletin 747– 53A2563, Revision 2, dated January 3, 2008, specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD. (h) Where Boeing Service Bulletin 747– 53A2563, Revision 2, dated January 3, 2008, specifies to contact Boeing for appropriate action, accomplish applicable actions before further flight using a method approved in accordance with the procedures specified in paragraph (k) of this AD. Report (i) At the applicable time specified in paragraph (i)(1) or (i)(2) of this AD: Submit a report of the findings (both positive and negative) of the inspections required by paragraph (f)(1) of this AD. One approved method for reporting is Appendixes B and C VerDate Aug<31>2005 17:23 Jan 30, 2008 Jkt 214001 as applicable of Boeing Service Bulletin 747– 53A2563, Revision 2, dated January 3, 2008. Send the report to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124–2207. The report must contain, at a minimum, the inspection results, a description of any discrepancies found, the airplane serial number, and the number of flight cycles and flight hours on the airplane. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120–0056. (1) If the inspection was done after the effective date of this AD: Submit the report within 30 days after the inspection. (2) If the inspection was done before the effective date of this AD: Submit the report within 30 days after the effective date of this AD. Actions Accomplished According to Previous Issue of Service Bulletin (j) Actions accomplished before the effective date of this AD according to Boeing Alert Service Bulletin 747–53A2563, dated March 29, 2007, are considered acceptable for compliance with the corresponding actions specified in this AD. Alternative Methods of Compliance (AMOCs) (k)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. (3) An AMOC that provides an acceptable level of safety may be used for any repair or limited return to service (LRTS) plan specified in this AD, if the repair or LRTS plan is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Seattle ACO, to make those findings. To be approved, the repair and LRTS plan must meet the certification basis of the airplane, and the approval must specifically refer to this AD. Issued in Renton, Washington, on January 18, 2008. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E8–1703 Filed 1–30–08; 8:45 am] BILLING CODE 4910–13–P PO 00000 Frm 00009 Fmt 4702 Sfmt 4702 DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2008–0091; Directorate Identifier 2007–NM–311–AD] RIN 2120–AA64 Airworthiness Directives; Boeing Model 747 Airplanes Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). AGENCY: SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 747 airplanes. This proposed AD would require modification of the refuel valve control unit for the reserve fuel tanks. This proposed AD would also require a revision to the FAA-approved maintenance program to incorporate airworthiness limitation (AWL) No. 28– AWL–20 or AWL No. 28–AWL–25, as applicable. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent lightning-induced electrical energy from entering a reserve fuel tank through the refuel valve, which could result in a fuel tank explosion and consequent loss of the airplane. We must receive comments on this proposed AD by March 17, 2008. ADDRESSES: You may send comments by any of the following methods: • Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments. • Fax: 202–493–2251. • Mail: U.S. Department of Transportation, Docket Operations, M– 30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE., Washington, DC 20590. • Hand Delivery: U.S. Department of Transportation, Docket Operations, M– 30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124–2207. DATES: Examining the AD Docket You may examine the AD docket on the Internet at https:// www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through E:\FR\FM\31JAP1.SGM 31JAP1 Federal Register / Vol. 73, No. 21 / Thursday, January 31, 2008 / Proposed Rules 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 Office (telephone 800–647–5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM–140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057–3356; telephone (425) 917–6501; fax (425) 917–6590. SUPPLEMENTARY INFORMATION: Comments Invited We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include ‘‘Docket No. FAA–2008–0091; Directorate Identifier 2007–NM–311–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 because 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 we receive about this proposed AD. sroberts on PROD1PC70 with PROPOSALS Discussion The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled ‘‘Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements’’ (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (‘‘SFAR 88,’’ Amendment 21–78, and subsequent Amendments 21–82 and 21–83). Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate VerDate Aug<31>2005 17:23 Jan 30, 2008 Jkt 214001 that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews. In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: single failures, single failures in combination with a latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action. We have determined that the actions identified in this AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane. Boeing has found that it is possible for unsafe energy to enter a reserve fuel tank through the refuel valve from induced electrical energy on the unshielded wire during a lightning strike. This condition, if not corrected, could result in a fuel tank explosion and consequent loss of the airplane. Relevant Service Information We have reviewed Boeing Alert Service Bulletin 747–28A2291, dated September 27, 2007. The service bulletin describes procedures for modifying the refuel valve control unit for the reserve fuel tanks. The modification includes installing a new angle bracket with two grounding studs, installing bonding ground jumpers between the refuel valve mounting bolts and the grounding studs, and doing a resistance check. We have also reviewed the Boeing 747–100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D6– 13747–CMR, Revision January 2007 (hereafter referred to as ‘‘Document D6– 13747–CMR’’). (For the purposes of PO 00000 Frm 00010 Fmt 4702 Sfmt 4702 5771 Document D6–13747–CMR, the Model 747SR series airplane is basically a Model 747–100 series airplane with certain modifications to improve fatigue life.) Section D of Document D6–13747– CMR describes new AWLs for fuel tank systems. The AWLs include: • AWL inspections, which are periodic inspections of certain features for latent failures that could contribute to an ignition source. • Critical design configuration control limitations (CDCCLs), which are limitation requirements to preserve a critical ignition source prevention feature of the fuel tank system design that is necessary to prevent the occurrence of an unsafe condition. The purpose of a CDCCL is to provide instruction to retain the critical ignition source prevention feature during configuration change that may be caused by alterations, repairs, or maintenance actions. A CDCCL is not a periodic inspection. Section D of Document D6–13747– CMR adds new fuel system AWL No. 28–AWL–20, which is a CDCCL to maintain the design features of the reserve tank fueling valve controller when the fueling valve controller is removed and replaced. We have also reviewed the Boeing 747–400 Maintenance Planning Data (MPD) Document, D621U400–9, Section 9, Revision 24, dated June 2006 (hereafter referred to as the ‘‘Boeing 747–400 MPD’’). Subsection D of the Boeing 747–400 MPD adds new fuel system AWL No. 28–AWL–25, which is a CDCCL to maintain the design features of the reserve tank fueling valve controller when the fueling valve controller is removed and replaced. FAA’s Determination and Requirements of This Proposed AD We are proposing this AD because we evaluated all relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the(se) same type design(s). This proposed AD would require the following actions: • Modification of the refuel valve control unit for the reserve fuel tanks. • Revision to the FAA-approved maintenance program to incorporate AWL No. 28–AWL–20, which would require maintaining the design features of the reserve tank fueling valve controller when the fueling valve controller is removed and replaced on Model 747–100, 747–100B, 747–100B SUD, 747–200B, 747–200C, 747–200F, 747–300, 747SR, and 747SP series airplanes. • Revision to the FAA-approved maintenance program to incorporate E:\FR\FM\31JAP1.SGM 31JAP1 5772 Federal Register / Vol. 73, No. 21 / Thursday, January 31, 2008 / Proposed Rules AWL No. 28–AWL–25, which would require maintaining the design features of the reserve tank fueling valve controller when the fueling valve controlled is removed and replaced on Model 747–400, 747–400D, and 747– 400F series airplanes. This proposed AD would also allow accomplishing the revision to the AWLs section of the Instructions for Continued Airworthiness in accordance with later revisions of the MPD as an acceptable method of compliance if they are approved by the Manager, Seattle Aircraft Certification Office, FAA. Costs of Compliance We estimate that this proposed AD would affect 300 airplanes of U.S. registry. The following table provides the estimated costs, at an average labor rate of $80 per hour, for U.S. operators to comply with this proposed AD. ESTIMATED COSTS Action Work hours Parts Cost per product Modification .................................................................... Maintenance program revision ....................................... Up to 7 ................... 1 ............................. Up to $286 ............. None ...................... Up to $846 ............. $80 ......................... Fleet cost Up to $253,800. $24,000. Authority for This Rulemaking List of Subjects in 14 CFR Part 39 Unsafe Condition 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. Air transportation, Aircraft, Aviation safety, Safety. (d) This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent lightninginduced electrical energy from entering a reserve fuel tank through the refuel valve, which could result in a fuel tank explosion and consequent loss of the airplane. sroberts on PROD1PC70 with PROPOSALS Regulatory Findings We 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 this 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. You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. VerDate Aug<31>2005 17:23 Jan 30, 2008 Jkt 214001 The Proposed Amendment Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows: PART 39—AIRWORTHINESS DIRECTIVES Compliance (e) Comply with this AD within the compliance times specified, unless already done. Modification 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 AD: Boeing: Docket No. FAA–2008–0091; Directorate Identifier 2007–NM–311–AD. Comments Due Date (a) We must receive comments by March 17, 2008. Affected ADs (b) None. Applicability (c) This AD applies to Boeing Model 747– 100, 747–100B, 747–100B SUD, 747–200B, 747–200C, 747–200F, 747–300, 747–400, 747–400D, 747–400F, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747–28A2291, dated September 27, 2007. Note 1: This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (h) of this AD. The request should include a description of changes to the required inspections that will ensure the continued operational safety of the airplane. PO 00000 Frm 00011 Fmt 4702 Sfmt 4702 (f) Within 60 months after the effective date of this AD, modify the refuel valve control unit for the reserve fuel tanks, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 747–28A2291, dated September 27, 2007. Maintenance Program Revision (g) Concurrently with accomplishing the modification required by paragraph (f) of this AD, revise the FAA-approved maintenance program by incorporating the information specified in paragraphs (g)(1) or (g)(2) of this AD, as applicable. (1) For Model 747–100, 747–100B, 747– 100B SUD, 747–200B, 747–200C, 747–200F, 747–300, 747SR, and 747SP series airplanes: Incorporate AWL No. 28–AWL–20 of Section D of the Boeing 747–100/200/300/SP Airworthiness Limitations (AWLs) and Certification Maintenance Requirements (CMRs), D6–13747–CMR, Revision January 2007, into the FAA-approved maintenance program. Accomplishing the revision in accordance with a later revision of Document D6–13747–CMR is an acceptable method of compliance if the revision is approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. (2) For Model 747–400, 747–400D, and 747–400F series airplanes: Incorporate AWL No. 28–AWL–25 of Subsection D of the Boeing 747–400 Maintenance Planning Data (MPD) Document, D621U400–9, Section 9, Revision 24, dated June 2006, into the FAAapproved maintenance program. Accomplishing the revision in accordance with a later revision of the MPD is an acceptable method of compliance if the revision is approved by the Manager, Seattle ACO, FAA. E:\FR\FM\31JAP1.SGM 31JAP1 Federal Register / Vol. 73, No. 21 / Thursday, January 31, 2008 / Proposed Rules Alternative Methods of Compliance (AMOCs) (h)(1) The Manager, Seattle ACO, FAA, ATTN: Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM–140S, 1601 Lind Avenue SW., Renton, Washington 98057– 3356; telephone (425) 917–6501; fax (425) 917–6590; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. (2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. Issued in Renton, Washington, on January 18, 2008. Ali Bahrami, Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. E8–1704 Filed 1–30–08; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. FAA–2008–0090; Directorate Identifier 2007–NM–312–AD] RIN 2120–AA64 Airworthiness Directives; Boeing Model 747 Airplanes Federal Aviation Administration (FAA), DOT. ACTION: Notice of proposed rulemaking (NPRM). sroberts on PROD1PC70 with PROPOSALS AGENCY: SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain Boeing Model 747 airplanes. This proposed AD would require measuring the electrical bond resistance between the motor operated valve (MOV) actuators and airplane structure for the main, center, auxiliary, and horizontal stabilizer fuel tanks as applicable, and corrective action if necessary. This proposed AD would also require a revision to the FAA-approved maintenance program to incorporate airworthiness limitation (AWL) No. 28– AWL–21 or AWL No. 28–AWL–27, as applicable. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent electrical current from flowing through a MOV actuator into a fuel tank, which could create a potential ignition source inside the fuel tank. This condition, in combination with flammable fuel vapors, could result in a VerDate Aug<31>2005 17:23 Jan 30, 2008 Jkt 214001 fuel tank explosion and consequent loss of the airplane. DATES: We must receive comments on this proposed AD by March 17, 2008. ADDRESSES: You may send comments by any of the following methods: • Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments. • Fax: 202–493–2251. • Mail: U.S. Department of Transportation, Docket Operations, M– 30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE., Washington, DC 20590. • Hand Delivery: U.S. Department of Transportation, Docket Operations, M– 30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service information identified in this AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124–2207. Examining the AD Docket You may examine the AD docket on the Internet at https:// www.regulations.gov; or in person at the Docket Management Facility 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 Office (telephone 800–647–5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt. FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM–140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057–3356; telephone (425) 917–6501; fax (425) 917–6590. SUPPLEMENTARY INFORMATION: Comments Invited We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include ‘‘Docket No. FAA–2008–0090; Directorate Identifier 2007–NM–312–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 because of those comments. We will post all comments we receive, without change, to https:// PO 00000 Frm 00012 Fmt 4702 Sfmt 4702 5773 www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD. Discussion The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled ‘‘Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements’’ (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (‘‘SFAR 88,’’ Amendment 21–78, and subsequent Amendments 21–82 and 21–83). Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews. In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: Single failures, single failures in combination with a latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action. We have determined that the actions identified in this AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination E:\FR\FM\31JAP1.SGM 31JAP1

Agencies

[Federal Register Volume 73, Number 21 (Thursday, January 31, 2008)]
[Proposed Rules]
[Pages 5770-5773]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-1704]


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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0091; Directorate Identifier 2007-NM-311-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Boeing Model 747 airplanes. This proposed AD would require 
modification of the refuel valve control unit for the reserve fuel 
tanks. This proposed AD would also require a revision to the FAA-
approved maintenance program to incorporate airworthiness limitation 
(AWL) No. 28-AWL-20 or AWL No. 28-AWL-25, as applicable. This proposed 
AD results from fuel system reviews conducted by the manufacturer. We 
are proposing this AD to prevent lightning-induced electrical energy 
from entering a reserve fuel tank through the refuel valve, which could 
result in a fuel tank explosion and consequent loss of the airplane.

DATES: We must receive comments on this proposed AD by March 17, 2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to https://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at https://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through

[[Page 5771]]

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 Office (telephone 800-
647-5527) is in the ADDRESSES section. Comments will be available in 
the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Sulmo Mariano, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6501; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-0091; 
Directorate Identifier 2007-NM-311-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 because 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 we 
receive about this proposed AD.

Discussion

    The FAA has examined the underlying safety issues involved in fuel 
tank explosions on several large transport airplanes, including the 
adequacy of existing regulations, the service history of airplanes 
subject to those regulations, and existing maintenance practices for 
fuel tank systems. As a result of those findings, we issued a 
regulation titled ``Transport Airplane Fuel Tank System Design Review, 
Flammability Reduction and Maintenance and Inspection Requirements'' 
(66 FR 23086, May 7, 2001). In addition to new airworthiness standards 
for transport airplanes and new maintenance requirements, this rule 
included Special Federal Aviation Regulation No. 88 (``SFAR 88,'' 
Amendment 21-78, and subsequent Amendments 21-82 and 21-83).
    Among other actions, SFAR 88 requires certain type design (i.e., 
type certificate (TC) and supplemental type certificate (STC)) holders 
to substantiate that their fuel tank systems can prevent ignition 
sources in the fuel tanks. This requirement applies to type design 
holders for large turbine-powered transport airplanes and for 
subsequent modifications to those airplanes. It requires them to 
perform design reviews and to develop design changes and maintenance 
procedures if their designs do not meet the new fuel tank safety 
standards. As explained in the preamble to the rule, we intended to 
adopt airworthiness directives to mandate any changes found necessary 
to address unsafe conditions identified as a result of these reviews.
    In evaluating these design reviews, we have established four 
criteria intended to define the unsafe conditions associated with fuel 
tank systems that require corrective actions. The percentage of 
operating time during which fuel tanks are exposed to flammable 
conditions is one of these criteria. The other three criteria address 
the failure types under evaluation: single failures, single failures in 
combination with a latent condition(s), and in-service failure 
experience. For all four criteria, the evaluations included 
consideration of previous actions taken that may mitigate the need for 
further action.
    We have determined that the actions identified in this AD are 
necessary to reduce the potential of ignition sources inside fuel 
tanks, which, in combination with flammable fuel vapors, could result 
in fuel tank explosions and consequent loss of the airplane.
    Boeing has found that it is possible for unsafe energy to enter a 
reserve fuel tank through the refuel valve from induced electrical 
energy on the unshielded wire during a lightning strike. This 
condition, if not corrected, could result in a fuel tank explosion and 
consequent loss of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-28A2291, dated 
September 27, 2007. The service bulletin describes procedures for 
modifying the refuel valve control unit for the reserve fuel tanks. The 
modification includes installing a new angle bracket with two grounding 
studs, installing bonding ground jumpers between the refuel valve 
mounting bolts and the grounding studs, and doing a resistance check.
    We have also reviewed the Boeing 747-100/200/300/SP Airworthiness 
Limitations (AWLs) and Certification Maintenance Requirements (CMRs), 
D6-13747-CMR, Revision January 2007 (hereafter referred to as 
``Document D6-13747-CMR''). (For the purposes of Document D6-13747-CMR, 
the Model 747SR series airplane is basically a Model 747-100 series 
airplane with certain modifications to improve fatigue life.) Section D 
of Document D6-13747-CMR describes new AWLs for fuel tank systems. The 
AWLs include:
     AWL inspections, which are periodic inspections of certain 
features for latent failures that could contribute to an ignition 
source.
     Critical design configuration control limitations 
(CDCCLs), which are limitation requirements to preserve a critical 
ignition source prevention feature of the fuel tank system design that 
is necessary to prevent the occurrence of an unsafe condition. The 
purpose of a CDCCL is to provide instruction to retain the critical 
ignition source prevention feature during configuration change that may 
be caused by alterations, repairs, or maintenance actions. A CDCCL is 
not a periodic inspection.
    Section D of Document D6-13747-CMR adds new fuel system AWL No. 28-
AWL-20, which is a CDCCL to maintain the design features of the reserve 
tank fueling valve controller when the fueling valve controller is 
removed and replaced.
    We have also reviewed the Boeing 747-400 Maintenance Planning Data 
(MPD) Document, D621U400-9, Section 9, Revision 24, dated June 2006 
(hereafter referred to as the ``Boeing 747-400 MPD''). Subsection D of 
the Boeing 747-400 MPD adds new fuel system AWL No. 28-AWL-25, which is 
a CDCCL to maintain the design features of the reserve tank fueling 
valve controller when the fueling valve controller is removed and 
replaced.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the(se) same type 
design(s). This proposed AD would require the following actions:
     Modification of the refuel valve control unit for the 
reserve fuel tanks.
     Revision to the FAA-approved maintenance program to 
incorporate AWL No. 28-AWL-20, which would require maintaining the 
design features of the reserve tank fueling valve controller when the 
fueling valve controller is removed and replaced on Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SR, and 
747SP series airplanes.
     Revision to the FAA-approved maintenance program to 
incorporate

[[Page 5772]]

AWL No. 28-AWL-25, which would require maintaining the design features 
of the reserve tank fueling valve controller when the fueling valve 
controlled is removed and replaced on Model 747-400, 747-400D, and 747-
400F series airplanes.
    This proposed AD would also allow accomplishing the revision to the 
AWLs section of the Instructions for Continued Airworthiness in 
accordance with later revisions of the MPD as an acceptable method of 
compliance if they are approved by the Manager, Seattle Aircraft 
Certification Office, FAA.

Costs of Compliance

    We estimate that this proposed AD would affect 300 airplanes of 
U.S. registry. The following table provides the estimated costs, at an 
average labor rate of $80 per hour, for U.S. operators to comply with 
this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
             Action                        Work hours                       Parts                   Cost per product                 Fleet cost
--------------------------------------------------------------------------------------------------------------------------------------------------------
Modification....................  Up to 7.....................  Up to $286..................  Up to $846..................  Up to $253,800.
Maintenance program revision....  1...........................  None........................  $80.........................  $24,000.
--------------------------------------------------------------------------------------------------------------------------------------------------------

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 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 this 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

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 FAA 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 AD:

Boeing: Docket No. FAA-2008-0091; Directorate Identifier 2007-NM-
311-AD.

Comments Due Date

    (a) We must receive comments by March 17, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-
400F, 747SR, and 747SP series airplanes, certificated in any 
category; as identified in Boeing Alert Service Bulletin 747-
28A2291, dated September 27, 2007.

    Note 1: This AD requires revisions to certain operator 
maintenance documents to include new inspections. Compliance with 
these inspections is required by 14 CFR 91.403(c). For airplanes 
that have been previously modified, altered, or repaired in the 
areas addressed by these inspections, the operator may not be able 
to accomplish the inspections described in the revisions. In this 
situation, to comply with 14 CFR 91.403(c), the operator must 
request approval for an alternative method of compliance according 
to paragraph (h) of this AD. The request should include a 
description of changes to the required inspections that will ensure 
the continued operational safety of the airplane.

Unsafe Condition

    (d) This AD results from fuel system reviews conducted by the 
manufacturer. We are issuing this AD to prevent lightning-induced 
electrical energy from entering a reserve fuel tank through the 
refuel valve, which could result in a fuel tank explosion and 
consequent loss of the airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Modification

    (f) Within 60 months after the effective date of this AD, modify 
the refuel valve control unit for the reserve fuel tanks, by 
accomplishing all of the applicable actions specified in the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
28A2291, dated September 27, 2007.

Maintenance Program Revision

    (g) Concurrently with accomplishing the modification required by 
paragraph (f) of this AD, revise the FAA-approved maintenance 
program by incorporating the information specified in paragraphs 
(g)(1) or (g)(2) of this AD, as applicable.
    (1) For Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747SR, and 747SP series airplanes: 
Incorporate AWL No. 28-AWL-20 of Section D of the Boeing 747-100/
200/300/SP Airworthiness Limitations (AWLs) and Certification 
Maintenance Requirements (CMRs), D6-13747-CMR, Revision January 
2007, into the FAA-approved maintenance program. Accomplishing the 
revision in accordance with a later revision of Document D6-13747-
CMR is an acceptable method of compliance if the revision is 
approved by the Manager, Seattle Aircraft Certification Office 
(ACO), FAA.
    (2) For Model 747-400, 747-400D, and 747-400F series airplanes: 
Incorporate AWL No. 28-AWL-25 of Subsection D of the Boeing 747-400 
Maintenance Planning Data (MPD) Document, D621U400-9, Section 9, 
Revision 24, dated June 2006, into the FAA-approved maintenance 
program. Accomplishing the revision in accordance with a later 
revision of the MPD is an acceptable method of compliance if the 
revision is approved by the Manager, Seattle ACO, FAA.

[[Page 5773]]

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle ACO, FAA, ATTN: Sulmo Mariano, 
Aerospace Engineer, Propulsion Branch, ANM-140S, 1601 Lind Avenue 
SW., Renton, Washington 98057-3356; telephone (425) 917-6501; fax 
(425) 917-6590; has the authority to approve AMOCs for this AD, if 
requested using the procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.

    Issued in Renton, Washington, on January 18, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-1704 Filed 1-30-08; 8:45 am]
BILLING CODE 4910-13-P
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.