E9-14677. Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, and 747SR 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 certain Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, and 747SR series airplanes. This proposed AD would require a one-time general visual inspection for missing fasteners in certain stringer-to-stringer clip joints at the station (STA) 760 through STA 940 frames, and related investigative and corrective actions if necessary. This proposed AD results from a report of broken and cracked frame shear ties, cracks on the frame doubler and frame web, and missing fasteners in the stringer (S)-10L stringer-to-stringer clip joint at the STA 820 frame. We are proposing this AD to detect and correct missing fasteners in the stringer-to-stringer clip joints, which could result in shear tie and skin cracks and rapid in-flight decompression of the airplane.

DATES:

We must receive comments on this proposed AD by August 7, 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: [phone].
• 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; telephone [phone]; fax [phone]; e-mail [e-mail]; 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 [phone]) 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 [phone]; fax [phone].

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-2009-0553; Directorate Identifier 2008-NM-199-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 a report indicating that, during routine maintenance, two operators found broken and cracked frame shear ties at the station (STA) 820 frame between stringer (S)-10AL and S-11L. Also, cracks were found on the frame doubler and frame web near S-11L. Further inspection showed missing fasteners in the S-10L stringer-to-stringer clip joint at the STA 820 frame. The cracks and missing fasteners were found on airplanes that had accumulated 16,087 and 16,421 total flight cycles.

Boeing analysis shows that the cracks were caused by increased load on the shear ties because of the missing fasteners in the stringer-to-stringer clip joint. Boeing investigation shows that similar cracking could occur in the frames adjacent to the tension ties if the stringer clip fasteners are not installed. Cracks in the shear ties, if not detected and corrected, could result in skin cracks and rapid in-flight decompression of the airplane.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2751, dated October 9, 2008. The service bulletin describes procedures for a one-time general visual inspection for missing fasteners in the S-10, S-10A, and S-11 stringer-to-stringer clip joints at the STA 760 through STA 940 frames, detailed and surface high frequency eddy current inspections to detect cracking of the adjacent frame and skin structure, installation of missing fasteners, and repairs of the shear ties, frame web, and/or skin. For airplanes on which the repair was done, the service bulletin describes procedures for detailed inspections to detect cracks of the repairs and the adjacent structure within 10 inches of the repairs. The service bulletin also specifies a detailed inspection of the repair and adjacent structure every 3,000 flight cycles.

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 Service Bulletin.”

Differences Between the Proposed AD and Service Bulletin

The service bulletin 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 84 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per product	Number of U.S.-registered airplanes	Fleet cost
Inspection	4	$80	$0	$320 per inspection cycle	84	$26,880 per inspection cycle.

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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new AD:

Boeing: Docket No. FAA-2009-0553; Directorate Identifier 2008-NM-199-AD.

Comments Due Date

(a) We must receive comments by August 7, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 747-100, 747-100B, 747-200B, 747-200C, 747-200F, and 747SR series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2751, dated October 9, 2008.

Subject

(d) Air Transport Association (ATA) of America Code 53: Fuselage.

Unsafe Condition

(e) This AD results from a report of broken and cracked frame shear ties, cracks on the frame doubler and frame web, and missing fasteners in the stringer (S)-10L stringer-to-stringer clip joint at the station (STA) 820 frame. We are proposing this AD to detect and correct missing fasteners at the stringer-to-stringer clip joints, which could result in shear tie and skin cracks and rapid in-flight decompression of the airplane.

Compliance

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

Inspection for Missing Fasteners

(g) Within 3,000 flight cycles after the effective date of this AD: Do a one-time general visual inspection for missing fasteners in the left and right side S-10, S-10A, and S-11 stringer-to-stringer clip joints at the STA 760 through 940 frames, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2751, dated October 9, 2008. If any fasteners are missing, before further flight, do detailed and surface high frequency eddy current inspections to detect cracking of the adjacent frame and skin structure in accordance with the Accomplishment Instructions of the service bulletin. Install all missing fasteners before further flight.

(h) If any crack is found during the inspection required by paragraph (g) of this AD: Before further flight, repair any cracked shear ties, frame web, and/or skin in accordance with Boeing Service Bulletin 747-53A2751, dated October 9, 2008.

(i) If any repair is done in accordance with paragraph (h) of this AD, before 20,000 total flight cycles or within 3,000 flight cycles from the repair installation, whichever occurs later: Do a detailed inspection of the repair(s) and the adjacent structure within 10 inches of the repair(s) for cracking. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles. If any crack is found during this inspection, before further flight, repair using a method approved in accordance with the procedures specified in paragraph (j) of this AD.

Alternative Methods of Compliance (AMOCs)

(j)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to Attn: Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Or, e-mail information to [e-mail].

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, in the FAA Flight Standards District Office (FSDO), or lacking a principal inspector, your local FSDO. The AMOC approval letter must specifically reference this AD.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it 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. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on June 15, 2009.

Dorr M. Anderson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.