Airworthiness Directives; Boeing Model 747-100, -200B, -200F, -200C, -100B, -300, -100B SUD, -400, -400D, -400F, and 747SR Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 747 series airplanes. This proposed AD would require a one-time inspection for discrepancies of the frame web and inner chords on the forward edge frame of the number 5 main entry door cutout, and related corrective action. This proposed AD is prompted by a report of cracking of the frame web and inner chords on the forward edge frame of the number 5 main entry door. We are proposing this AD to find and fix discrepancies of the frame web and inner chords, which could result in cracking, subsequent severing of the frame, and consequent rapid depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by August 30, 2004.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed 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.
• By 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.

You can get the service information identified in this proposed AD from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov,, or 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.

FOR FURTHER INFORMATION CONTACT:

Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-18601; Directorate Identifier 2004-NM-34-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed 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 proposed AD. Using the search function of that website, 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 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 that affect you. You can get more information about plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

You can examine the AD docket in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received a report of cracking of the frame web and inner chords at body station (BS) 2231, stringer 26L, on a Model 747 series airplane. The service history shows that both chords (forward and aft) and the web on the forward edge frame of the number 5 main entry door (MED) cutout were severed. The inboard chord of the number 5 MED lower main sill goes through a cutout in the BS 2231 frame at stringer 26. Investigation revealed that, during production, the inboard chord of the lower main sill of the door can rub against the BS 2231 frame. Such rubbing can cause nicks, scratches and/or gouges in the frame inner chords and web, and subsequent cracking. Cracks in the inner chords and web could extend and fully sever the frame, which could result in rapid depressurization of the airplane.

Related AD

On July 26, 2001, we issued AD 2001-16-02, amendment 39-12370 (66 FR 41440, August 8, 2001), which is applicable to certain Boeing Model 747 series airplanes. That AD requires repetitive inspections to find cracking of the frame web, strap, inner chords, and inner chord angle of the forward edge frame of the number 5 main entry door cutout, and repair if necessary. The actions specified by that AD are intended to find and fix such cracking, which could result in severing of the frame, inability of the edge frame to react door stop loads, and consequent rapid depressurization of the airplane.

Relevant Service Information

We have reviewed and approved Boeing Alert Service Bulletin 747-53A2494, dated September 18, 2003, which describes procedures for a one-time detailed visual inspection for discrepancies (nicks, scratches, and/or gouges) of the frame web and inner chords (forward and aft) of the forward edge frame of the number 5 main entry door cutout, and related corrective action. The corrective action includes a surface high frequency eddy current inspection for cracking on the frame inner chords of BS 2231, rework of any discrepancies, and repair of any cracking. The service bulletin references certain 747 Structural Repair Manuals for rework/repair procedures. The service bulletin also recommends contacting the manufacturer for repair instructions. The service bulletin indicates that if the repetitive inspections recommended in Boeing Alert Service Bulletin 747-53A2450, Revision 2, dated January 4, 2001 (required by AD 2001-16-02) are being done, the one-time inspection is not necessary. We have determined that accomplishing the actions specified in the service bulletin will adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require a one-time inspection for discrepancies of the frame web and inner chords of the forward edge frame of the number 5 main entry door cutout, and related corrective action. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and Service Bulletin.'' Accomplishment of the actions required by this proposed AD would not terminate the repetitive inspections required by AD 2001-16-02.

Differences Between the Proposed AD and Service Bulletin

The service bulletin refers to a “detailed visual inspection” for discrepancies of the frame web and inner chords. We have determined that the procedures in the service bulletin should be described as a “detailed inspection.” We have included Note 1 to define this type of inspection.

As discussed previously, the referenced service bulletin specifies that if the repetitive inspections recommended in Boeing Alert Service Bulletin 747-53A2450 (and required by AD 2001-16-02) are currently being done, the one-time inspection required by this proposed AD is not necessary. However, we have determined that the repetitive inspections required by AD 2001-16-02 would not address the unsafe condition identified in this proposed AD. The one-time inspection required by this proposed AD is to find nicks, scratches, and/or gouges that can lead to cracking, and repair of those discrepancies. Therefore, we have determined that the proposed one-time inspection is required prior to or concurrently with the next inspection required by AD 2001-16-02.

The referenced service bulletin also specifies that operators may contact the manufacturer for disposition of certain repair conditions, but this proposed AD would require operators to repair those conditions per a method approved by the Manager of the Seattle Aircraft Certification Office of the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

Costs of Compliance

This proposed AD would affect about 220 airplanes of U.S. registry and 1,055 airplanes worldwide. The proposed inspection would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the inspection proposed by this AD for U.S. operators is $28,600, or $130 per airplane.

Regulatory Findings

We have 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 that the 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.

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

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.