Airworthiness Directives: Boeing Model 747 Airplanes

As Enacted ( Federal Register)

Cited authorities 2

Cited in

Federal Register: February 23, 2009 (Volume 74, Number 34)

Proposed Rules

Page 8034-8036

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

DOCID:fr23fe09-9

Proposed Rules

Federal Register

This section of the FEDERAL REGISTER contains notices to the public of the proposed issuance of rules and regulations. The purpose of these notices is to give interested persons an opportunity to participate in the rule making prior to the adoption of the final rules.

Page 8034

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration 14 CFR Part 39

Docket No. FAA-2009-0136; Directorate Identifier 2008-NM-171-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 repetitive inspections for cracking of the fuselage frames in section 41, and corrective actions if necessary. This proposed AD results from reports of cracking in fuselage frames made of 2024 aluminum alloy that were installed during previous modification of the frames in section 41 and during production. We are proposing this AD to detect and correct frame cracks, which could result in cracking of the adjacent fuselage skin and consequent rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by April 9, 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 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-2009-0136;

Directorate Identifier 2008-NM-171-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.

Other Related Rulemaking

On January 16, 1990, we issued AD 90-06-06, amendment 39-6490 (55

FR 8374, March 7, 1990), for certain Boeing Model 747 airplanes. That

AD requires incorporation of certain structural modifications. That AD resulted from reports of incidents involving fatigue cracking and corrosion in transport category airplanes that are approaching or have exceeded their design life goal. These incidents jeopardized the airworthiness of the affected airplanes. We issued that AD to correct degradation in the structural capabilities of the affected airplanes.

The requirements in that AD reflect the FAA's decision that long-term continued operational safety should be ensured by actual modification of the airframe rather than repetitive inspection.

On December 26, 2007, we issued AD 2004-07-22 R1, amendment 39- 15326 (73 FR 1052, January 7, 2008), for certain Boeing Model 747 airplanes. That AD requires that the FAA-approved maintenance inspection program be revised to include inspections that will give no less than the required damage tolerance rating for each structural significant item, and repair of cracked structure. That AD resulted from a report of incidents involving fatigue cracking in transport category airplanes that are approaching or have exceeded their design service objective. We issued that AD to ensure the continued structural integrity of all 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.

Discussion

We have received reports of cracking in fuselage frames made of 2024 aluminum alloy material that were installed during previous modification of frames in section 41 required by AD 90-06-06. One crack was in the frame web at body station 340, at a fastener location common to the upper chord of the upper deck floor beams. The other crack was in the frame web and doubler at body station 420 and was also at a fastener location common to the upper deck floor beams. The frame crack in body station 340 was found 9,757 flight

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cycles after the 2024 aluminum alloy frame was installed during modification of the frames in section 41. The frame crack in body station 420 was found 6,441 flight cycles after the 2024 aluminum alloy frame was installed during modification of the frames in section 41.

This condition, if not corrected, could result in cracking of the adjacent fuselage skin and consequent rapid decompression of the airplane.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletins 747-53A2732 and 747-53A2753, both dated August 28, 2008. Boeing Alert Service Bulletins 747-53A2732 and 747-53A2753, both dated August 28, 2008, describe procedures for repetitive internal detailed inspections for cracking of the fuselage frames in section 41, and corrective actions if necessary.

Boeing Alert Service Bulletins 747-53A2732 and 747-53A2753, both dated

August 28, 2008, also describe procedures for an optional special detailed inspection behind the flight engineers panel on the upper deck and the P14 and P15 electrical terminal panels using a borescope. The corrective actions include repairing any crack found during any inspection in accordance with the applicable Work Instructions, or by contacting Boeing for repair data.

The compliance times for the initial inspections specified in

Boeing Alert Service Bulletin 747-53A2732 range from before the accumulation of 10,000 or 20,000 flight cycles depending on airplane configuration and location since modification of the frames in section 41 was done, or for airplanes on which 2024 aluminum alloy material was installed in production, 20,000 total flight cycles, or within 1,500 flight cycles after the date on this service bulletin; whichever occurs latest. The inspections must be repeated at intervals not to exceed 3,000 or 6,000 flight cycles, as applicable.

The compliance times for the initial inspections specified in

Boeing Alert Service Bulletin 747-53A2753 range from before the accumulation of 15,000 or 30,000 total flight cycles depending on airplane configuration, or within 1,000 flight cycles after the date on this service bulletin, whichever occurs later. If no cracks are found or the cracks have been repaired, the inspections must be repeated at intervals not to exceed 2,400 or 3,000 flight cycles, as applicable.

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 these same type designs. 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 Alert Service

Bulletins.''

Differences Between the Proposed AD and Alert Service Bulletins

Boeing Alert Service Bulletins 747-53A2732 and 747-53A2753, both dated August 28, 2008, specify that you may contact the manufacturer for instructions on how to repair certain conditions, but this proposed

AD requires you to repair 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 Delegation Option Authorization Organization who has been authorized by the FAA to make those findings.

Costs of Compliance

We estimate that this proposed AD would affect 165 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

Average

Work

labor

Number of U.S-

Inspection

hours

rate per

Cost per product

registered

Fleet cost hour

airplanes