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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. FAA-2008-1072; Directorate Identifier 2008-NM-109-AD] 
          - RIN 2120-AA64 

# 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, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747SR, and 747SP series airplanes. This proposed AD would require inspecting for skin cracks at the shear tie end fastener locations of the fuselage frames, and repair if necessary. This proposed AD results from a wide-spread fatigue damage assessment of Model 747 airplanes. We are proposing this AD to detect and correct cracks in the fuselage skin that can propagate and grow, resulting in a loss of structural integrity and a sudden decompression of the airplane during flight. 

# DATES:

We must receive comments on this proposed AD by November 24, 2008. 

# 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, P.O. Box 3707, Seattle, Washington 98124-2207. 

## 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-2008-1072; Directorate Identifier 2008-NM-109-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 

As part of a recent wide-spread fatigue damage (WFD) assessment of Boeing Model 747 airplanes, the manufacturer revealed that an inspection for skin cracks at certain shear tie end fastener locations of the fuselage frames is necessary. This is one of the structural areas determined by analysis and fleet history to be susceptible to WFD and requires service action in the form of inspections and/or a modification. Cracks in the fuselage skin can propagate and grow, resulting in loss of structural integrity and a sudden decompression of the airplane during flight. 

## Relevant Service Information 

We have reviewed Boeing Alert Service Bulletin 747-53A2682, dated May 8, 2008. The service bulletin describes procedures for an external detailed inspection, or an alternative external high frequency eddy current (HFEC) inspection, for skin cracks at the shear tie end fastener locations of the fuselage frames between Station (STA) 540 to 980 (STA 780 on 747SP airplanes), Stringers 23 through 47 on the left and right sides, and repair if necessary. If no skin crack is found, the applicable inspection is repeated. If any skin crack is found, the crack must be repaired, as specified in the 747 Structural Repair Manual (SRM). If any crack is found in an SRM skin repair, the service bulletin recommends contacting Boeing for repair data. 

The compliance time for the external detailed inspections and the alternative external HFEC inspections is before 22,000 total flight cycles or within 2,000 flight cycles after the date on the service bulletin, whichever occurs later. If no skin crack is found during the external detailed inspection, the inspection is repeated within 3,000 flight cycles after the initial inspection is done, and thereafter at intervals not to exceed 3,000 flight cycles. If no skin crack is found during the alternative external HFEC inspection, the inspection is repeated within 6,000 flight cycles after the initial inspection is done, and thereafter at intervals not to exceed 6,000 flight cycles. If any crack is found in the skin or skin repair during any inspection, the repair is done before further flight. 

## 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                           ( print page 58902)                        develop in other products of the same type designs. This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between Proposed AD and Service Information.”                 

## Differences Between Proposed AD and Service Information 

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.

Although the service bulletin specifies that the repetitive inspections are optional, this proposed AD requires the repetitive inspections. We find repeating the inspections at regular intervals will ensure an acceptable level of safety for all airplanes affected by the proposed AD. This difference has been coordinated with Boeing. 

## Costs of Compliance 

We estimate that this proposed AD would affect 147 airplanes of U.S. registry. We also estimate that it would take about 30 work-hours for the detailed inspection, or 49 work hours for the HFEC inspection, per product, to comply with this proposed AD. The average labor rate is $80 per work-hour. Based on these figures, we estimate the cost of this proposed AD to the U.S. operators to be $352,800 or $576,240, or $2,400 or 3,920 per product. 

## 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
      - 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 

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

**Boeing:**                                 Docket No. FAA-2008-1072; Directorate Identifier 2008-NM-109-AD.                             

## Comments Due Date 

(a) We must receive comments by November 24, 2008. 

## Affected ADs 

(b) None.

## Applicability 

(c) This AD applies to Boeing 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 747-53A2682, dated May 8, 2008. 

## Unsafe Condition 

(d) This AD results from a wide-spread fatigue damage assessment of Model 747 airplanes. We are issuing this AD to detect and correct cracks in the fuselage skin that can propagate and grow, resulting in a loss of structural integrity and sudden decompression of the airplane during flight. 

## Compliance 

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

## Inspections/Repair 

(f) Except as provided by paragraphs (g) and (h) of this AD: At the applicable compliance times specified in paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2682, dated May 8, 2008, do an external detailed inspection or external high frequency eddy current inspection for skin cracks at the shear tie end fastener locations of the fuselage frames, and repair any skin cracks before further flight, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of the service bulletin. Repeat the applicable inspection thereafter at the applicable interval specified in paragraph 1.E. of the service bulletin. 

## Exceptions to the Service Bulletin 

(g) Where paragraph 1.E. of Boeing Alert Service Bulletin 747-53A2682, dated May 8, 2008, specifies counting the compliance time from “* * * the date on this service bulletin,” this AD requires counting the compliance time from the effective date of this AD. 

(h) If any crack is found in a structural repair manual skin repair during any inspection required by paragraph (f) of this AD, and Boeing Alert Service Bulletin 747-53A2682, dated May 8, 2008, specifies to contact Boeing for repair: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (i) of this AD. 

## Alternative Methods of Compliance (AMOCs) 

(i)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, ATTN: 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; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. 

(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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. 

                                (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                                       ( print page 58903)                                    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 September 26, 2008. 

Michael Kaszycki, 

Acting Manager, Transport Airplane Directorate,  Aircraft Certification Service.

[FR Doc. E8-23821 Filed 10-7-08; 8:45 am] 

BILLING CODE 4910-13-P