AD 2004-22-05

Effective November 12, 2004.

The incorporation by reference of a certain publication listed in the AD is approved by the Director of the Federal Register as of November 12, 2004.

We must receive comments on this AD by December 27, 2004.

Use one of the following addresses to submit comments on this AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.

• Government-wide rulemaking web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.

• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.

• Fax: (202) 493-2251.

• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, 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. You can examine this information at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

Technical information: Sue Lucier, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6438; fax (425) 917-6590.

Plain language information: Marcia Walters, marcia.walters@faa.gov.

We have recently received a report indicating that wear of the fuselage skin was found between body stations 860 and 1006 on a Boeing Model 737-300 series airplane. Subsequently, an 18-inch crack developed in the area of the wear. Fuselage skin wear is attributed to the movement of the blade seals, which provide an aerodynamic seal between the dorsal fin fairing and the fuselage skin. Wear damage of the fuselage skin, if not found and fixed, could result in fatigue cracking due to cabin pressurization, and consequent rapid in-flight decompression of the airplane fuselage.

We have reviewed Boeing Message Number 1-QXO35, dated October 13, 2004. The message describes procedures for repetitive detailed inspections of the fuselage skin under the dorsal fin assembly for discrepancies ( i.e., wear or cracking), and contacting Boeing for repair instructions. The message also describes procedures for accomplishing a detailed inspection for discrepancies if any repair doubler is installed.

We have also reviewed Boeing Service Bulletin 737-55-1057, Revision 1, dated July 22, 1999; specified in the Boeing message as an additional source of service information for accomplishing the actions. Part I of the Accomplishment Instructions of the service bulletin describes procedures for inspecting for discrepancies of the fuselage skin under the dorsal fin assembly. The discrepancies include chafing, wear damage, and lack of abrasion-resistant coating.

The unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. Therefore, we are issuing this AD to find and fix discrepancies of the fuselage skin, which could result in fatigue cracking due to cabin pressurization, and consequent rapid in-flight decompression of the airplane fuselage. This AD requires accomplishing the actions specified in Boeing Message Number 1-QXO35, described previously, except as discussed under “Difference Between the AD and Boeing Message Number 1-QXO35.”

The message specifies that operators may contact the manufacturer for repair instructions, but this AD requires you to repair cracking in one of the following ways:

• Using a method that we approve; or

• Using data that meet the type certification basis of the airplane, and that have been approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make those findings.

Although the message recommends reporting any fuselage skin cracking found during the detailed inspections, this AD does not require that action.

An unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days.

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19461; Directorate Identifier 2004-NM-169-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of our docket Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications with you. You can get more information about plain language at http://www/faa.gov/language and http://www.plainlanguage.gov

We have determined that 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 the 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.

We prepared a regulatory evaluation of the estimated costs to comply with this AD. See the ADDRESSES section for a location to examine the regulatory evaluation.

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):