Airworthiness Directives; Boeing 747-200C and -200F Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for all Boeing 747-200C and -200F series airplanes. This proposed AD would require a high frequency eddy current inspection for cracks of certain fastener holes, and corrective action if necessary. This proposed AD would also require repetitive replacements of the upper chords, straps (or angles), and radius fillers of certain upper deck floor beams, and, for any replacement that is done, detailed and open-hole HFEC inspections for cracks of the modified upper deck floor beams, and corrective actions if necessary. This proposed AD results from a report from the manufacturer that the accomplishment of certain existing inspections, repairs, and modifications is not adequate to ensure the structural integrity of the affected 7075 series aluminum alloy upper deck floor beam upper chords on airplanes that have exceeded certain thresholds. We are proposing this AD to prevent cracking of the upper chords and straps (or angles) of the floor beams, which could lead to failure of the floor beams and consequent loss of controllability, rapid decompression, and loss of structural integrity of the airplane.

DATES:

We must receive comments on this proposed AD by August 20, 2009.

ADDRESSES:

You may send comments by any of the following methods:

• Federal eRulemaking Portal: Go to http://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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1, fax 206-766-5680; e-mail me.boecom@boeing.com; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221 or 425-227-1152.

Examining the AD Docket

You may examine the AD docket on the Internet at http://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:

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437; 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-2009-0608; Directorate Identifier 2008-NM-215-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 http://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

We have received reports that operators have found cracks in the upper chords and straps (or angles) of the upper deck floor beams. The airplanes had accumulated between 16,264 and 23,561 total flight cycles. In addition, we received a report from the manufacturer that the accomplishment of certain existing inspections, repairs, and modifications is not adequate to ensure the structural integrity of the affected 7075 series aluminum alloy upper deck floor beam upper chords on airplanes that have exceeded certain thresholds. Cracks in the upper chords or straps (or angles) of an upper deck floor beam that are not found and repaired could become large and fully sever the floor beam. A severed floor beam can lead to large deflection or deformation of the floor and of the adjacent body skin, frames, and stringers, and could result in damage and unintended inputs to the wire bundles and control cables routed through the floor beams which could affect airplane controllability. If not corrected, adjacent severed floor beams could result in consequent loss of controllability, rapid decompression, and loss of structural integrity of the airplane.

Related ADs

As a result of these reports of cracks, Boeing issued Alert Service Bulletin 747-53A2439, dated July 5, 2001. Boeing Alert Service Bulletin 747-53A2439 provides procedures for an open-hole high frequency eddy current (HFEC) or surface HFEC inspection to find fatigue cracking in the upper chord of the upper deck floor beams, and applicable related investigative and corrective actions. The actions in Boeing Alert Service Bulletin 747-53A2439, dated July 5, 2001, are required by AD 2006-08-02, amendment 39-14556 (71 FR 18618, April 12, 2006).

In addition, Boeing has received many reports of cracks in the upper chords and straps (or angles) of the affected floor beams at the fastener locations where the upper chords attach to the body frames. As a result of these reports of cracks, Boeing issued Alert Service Bulletin 747-53A2420, dated March 26, 1998; and Boeing Alert Service Bulletin 747-53A2429, dated March 22, 2001. Boeing Alert Service Bulletin 747-53A2420 provides procedures for detailed and open-hole HFEC inspections of the upper chords of the floor beams, and applicable corrective actions. Boeing Alert Service Bulletin 747-53A2429 provides procedures for detailed and open-hole HFEC inspections and modification of the upper chords of the floor beams, and applicable corrective actions. The actions in Boeing Alert Service Bulletin 747-53A2420, dated March 26, 1998; and Boeing Alert Service Bulletin 747-53A2429, dated March 22, 2001, are required by AD 2005-07-21, amendment 39-14046 (70 FR 18277, April 11, 2005).

To preclude widespread fatigue damage, we have determined that we should not rely solely on the inspections required by AD 2006-08-02 and AD 2005-07-21 indefinitely. We have determined to mandate a modification of the floor beams and related investigative actions in this separate AD action, rather than superseding the related ADs.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2696, dated October 16, 2008. This service bulletin describes procedures for removing the upper chords from the upper deck floor beams at stations (STA) 340 to 440 inclusive, 500, and 520, an open-hole HFEC inspection for cracks of all the fastener holes accessed for upper chord removal, and if any cracking is found, contacting Boeing for repair information, and doing the repair. This service bulletin also describes procedures for fabricating and installing new upper chords and straps (or angles) of the upper deck floor beams at STA 340 to 440 inclusive, 500, and 520 with new upper chords, straps (or angles), and radius fillers.

For any airplane on which a replacement is done, the service bulletin recommends detailed and HFEC inspections for cracks of the modified upper deck floor beams, and for airplanes on which any cracking is found, contacting Boeing for repair instructions and repairing if necessary. For all airplanes, this service bulletin specifies to do detailed and HFEC inspections for cracks of the upper deck floor beams within 15,000 flight cycles after the replacement is done, or within 1,500 flight cycles, whichever occurs later. This service bulletin also specifies replacing the upper chords and straps (or angles) of the upper deck floor beams within 6,000 flight cycles after doing the detailed and HFEC inspections. The service bulletin also specifies repetitive detailed and HFEC inspections within 15,000 flight cycles after the upper chord replacement modification.

Boeing Alert Service Bulletin 747-53A2696 refers to Boeing Alert Service Bulletin 747-53A2429, Revision 2, dated October 16, 2008; and Boeing Alert Service Bulletin 747-53A2439, Revision 2, dated July 17, 2008; as additional sources of information for doing the post-modification inspections.

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 same type design. This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Bulletin.”

Differences Between the Proposed AD and the Service Bulletin

Boeing Alert Service Bulletin 747-53A2696, dated October 16, 2008, specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization whom we have authorized to make those findings.

Costs of Compliance

We estimate that this proposed AD would affect 25 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

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
• Incorporation by reference
• 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.