2010-9112. Airworthiness Directives; The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP 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 Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes. This proposed AD would require repetitive detailed inspections of certain overwing intercostal webs, and related investigative and corrective actions if necessary. This proposed AD results from reports of cracks in overwing intercostal webs. We are proposing this AD to detect and correct such cracking, which could grow and result in a severed intercostal. If an intercostal is severed, cracks could develop in the adjacent frame structure and skin, resulting in a rapid loss of cabin pressure.

DATES:

We must receive comments on this proposed AD by June 7, 2010.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; 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.

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 (ACO), 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-2010-0383; Directorate Identifier 2009-NM-214-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 several reports of cracks in overwing intercostal webs between station (STA) 1160 and STA 1220. Most of the cracks were found near the intercostal lower chord and a few cracks were found near the intercostal upper chord. The cracks ranged from 0.2 inch to 3.5 inches long. The cracks are caused by cyclic buckling of the web from normal flight loads. The earliest report of a web crack occurred on an airplane with 3,697 flight cycles; however, no cracks have been reported in the upper or lower chord of the overwing intercostals. This condition, if not corrected, could result in crack growth and a severed intercostal. If an intercostal is severed, cracks could develop in the adjacent frame structure and skin, resulting in rapid loss of cabin pressure.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009. Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, describes procedures for doing a repetitive detailed inspection for cracking of the left-side and right-side overwing intercostal webs at STAs 1160, 1180, 1200, and 1220, and related investigative and corrective actions if necessary. The related investigative action is doing a detailed inspection for cracking of the upper chord, lower chord, and stiffener of the intercostal and adjacent frame assembly structure if a crack is found in the web of an overwing intercostal. Depending on findings, the corrective actions are replacing any cracked overwing intercostal web (the replacement of the overwing intercostal web includes doing an open-hole HFEC inspection for cracking of the fastener holes common to the replacement); and contacting Boeing for repair instructions of any cracked intercostal upper chord, lower chord, stiffener, or adjacent frame assembly structure, and of any crack found during any open-hole HFEC inspections, and doing the repair.

For any airplane having a STA 1160, 1180, 1200, or 1220 overwing intercostal web that has been replaced in accordance with this service bulletin, Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, specifies procedures for doing repetitive detailed inspections for cracking of the replaced web, and related investigative and corrective actions if necessary. Related investigative actions include doing a detailed inspection for cracking of the upper chord, lower chord, and stiffener of the intercostal, and adjacent frame assembly structure. Corrective actions include replacing any cracked overwing intercostal web; and contacting Boeing for repair instructions of any cracked intercostal upper chord, lower chord, stiffener, or adjacent frame assembly structure, and of any crack found during any open-hole HFEC inspections, and doing the repair.

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 Rule and Service Bulletin.”

Differences Between the Proposed Rule and Service Bulletin

Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, 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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.

Costs of Compliance

We estimate that this proposed AD would affect 86 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Table—Estimated costs

Action	Work hours	Average labor rate per hour	Parts	Cost per product	Number of U.S.-registered airplanes	Fleet cost
Inspection	4	$85	None	$340 per inspection cycle	86	$29,240 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:

The Boeing Company: Docket No. FAA-2010-0383; Directorate Identifier 2009-NM-214-AD.

Comments Due Date

(a) We must receive comments by June 7, 2010.

Affected ADs

(b) None.

Applicability

(c) This AD applies to The Boeing Company Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009.

Subject

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

Unsafe Condition

(e) This AD results from reports of cracks in overwing intercostal webs between station (STA) 1160 and STA 1220. The Federal Aviation Administration is issuing this AD to detect and correct such cracking, which could grow and result in a severed intercostal. If an intercostal is severed, cracks could develop in the adjacent frame structure and skin, resulting in a rapid loss of cabin pressure.

Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Repetitive Inspections of the Overwing Intercostal Web

(g) Before the accumulation of 8,000 total flight cycles, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later: Do a detailed inspection of the left-side and right-side STAs 1160, 1180, 1200, and 1220 overwing intercostal webs, and all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, except as required by paragraph (i) of this AD. Do all applicable related investigative and corrective actions before further flight. If no cracking is found during any detailed inspection, repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.

(h) For any airplane with an overwing intercostal web replaced in accordance with Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009: Within 6,000 flight cycles after the web was replaced, do a detailed inspection of the replacement overwing intercostal web, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, except as required by paragraph (i) of this AD. Do all applicable related investigative and corrective actions before further flight. If no cracking is found during any detailed inspection, repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles.

Exception to Service Bulletin

(i) If any cracking is found during any inspection required by this AD, and Boeing Alert Service Bulletin 747-53A2750, dated August 27, 2009, specifies contacting Boeing for appropriate action: Before further flight, repair the cracking using a method approved in accordance with the procedures provided 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 (ACO), 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Information may be e-mailed 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, or lacking a principal inspector, your local Flight Standards District Office. 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 the Boeing Commercial Airplanes Organization Designation Authorization that 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 April 9, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.