AD 2011-01-15

This AD is effective January 25, 2011.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of January 25, 2011.

We must receive comments on this AD by February 24, 2011.

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 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.

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6440; fax (425) 917-6590; e-mail: nancy.marsh@faa.gov.

We have received reports of cracking in the fuselage skin of the crown skin panel. On one airplane, the crack was 10.75 inches long, midway between stations (STA) 420 and 439, just above the lap joint at stringer 4L (left) of the chem-milled step. The airplane had accumulated 24,631 total flight cycles. On another airplane, there was an opening from a crack in the fuselage above and aft of the passenger entry doorway. One edge of the opening ran approximately 18 inches in the forward-to-aft direction; the other edge ran approximately 12 inches along the chem-milled pocket edge above stringer 4L. Additionally, a 1.3-inch crack was found in the skin forward of the opening in the adjacent skin bay also in the chem-milled step above stringer 4L. The airplane had accumulated 22,450 total flight cycles. The subject cracking is attributed to fatigue. Such cracking could initiate at multiple locations on the interior surface along the chem-milled step edges above the stringer 4L or 4R (right) lap splices of the skin. This condition, if not corrected, could result in pressure venting and consequent rapid decompression of the airplane.

We reviewed Boeing Special Attention Service Bulletin 757-53-0097, dated November 22, 2010. The service information describes procedures for repetitive inspections for cracking of the fuselage skin of the crown skin panel along the chem-milled step at stringers S-4L and S-4R, from STA 297 through 439, as specified in the options below. If any crack is found, the service bulletin recommends contacting Boeing for damage removal and repair instructions.

• Option A Inspection: An external detailed inspection of the STA 297 through 439 crown skin panel at stringers S-4L and S-4R lap joints.

• Option B Inspection: An external sliding probe eddy current inspection of the STA 297 through 439 crown skin panel at stringers S-4L and S-4R lap joints.

• Option C Inspection: An external spot probe medium frequency eddy current inspection of the STA 297 through 439 crown skin panel at stringers S-4L and S-4R lap joints.

The compliance time for all of the initial inspections is before the accumulation of 15,000 total flight cycles, or within 30 days after the original issue date of the service bulletin, whichever occurs later. The repetitive interval is specified below.

• Option A: At intervals not to exceed 30 flight cycles.

• Option B: At intervals not to exceed 300 flight cycles.

• Option C: At intervals not to exceed 200 flight cycles.

The initial external detailed inspection specified in Option A, if done, is repeated until either the Option B or Option C inspection is accomplished within 90 days after the original date of the service bulletin, and thereafter, either the Option B or Option C inspection is repeated. Accomplishing the Option B or Option C inspection would eliminate the need for the Option A inspection.

A detailed external inspection may be applied no more than once for each repeat interval of 300 flight cycles to extend the Option B repeat inspection up to 330 flight cycles, and for each repeat interval of 200 flight cycles to extend the Option C inspection up to 230 flight cycles—not to exceed 30 flight cycles after accomplishing the inspection.

Boeing Special Attention Service Bulletin 757-53-0097, dated November 22, 2010, also includes certain exceptions to the inspection of the edge of the chem-milled pocket under an existing external repair doubler.

We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

This AD requires accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the AD and the Service Information.”

Boeing Special Attention Service Bulletin 757-53-0097, dated November 22, 2010, specifies to contact the manufacturer for instructions on how to repair certain conditions, but this AD would require repairing those conditions in one of the following ways:

• In accordance with a method that we approve; or

• Using data that meet the certification basis of the airplane, and that have been approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.

We consider this AD interim action. An investigation is ongoing and no terminating action has been developed yet.

An unsafe condition exists that requires the immediate adoption of this AD. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because fatigue cracking of the fuselage skin of the crown skin panel could result in pressure venting and consequent rapid decompression of the airplane. Therefore, we find that notice and opportunity for prior public comment are impracticable and that good cause exists for making this amendment effective in less than 30 days.

This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA- 2010-1280; Directorate Identifier 2010-NM-270-AD;” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this 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 AD.

We estimate that this AD affects 683 airplanes of U.S. registry.

We estimate the following costs to comply with this AD:

We have received no definitive data that would enable us to provide a cost estimate for the on-condition actions specified in this AD.

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.

This AD will not have federalism implications under Executive Order 13132. This AD will 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 this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866,

(2) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 14 CFR part 39 as follows:

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

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):