Airworthiness Directives; Boeing Model 747-100B SUD, -300, -400, and -400D 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 747-100B SUD, -300, -400, and -400D series airplanes. This proposed AD would require a one-time inspection for discrepancies of the fuselage frame to tension tie joints at body stations (BS) 1120 through 1220 and to determine if steel splice plates are installed on the fuselage frames, and related investigative and corrective actions. This proposed AD is prompted by reports indicating that severed tension ties were found at the fuselage frame joints at BS 1120 and 1140. We are proposing this AD to prevent fatigue cracking of the fuselage frame to tension tie joints, which could result in severing of the tension ties and consequent rapid decompression of the airplane fuselage.

DATES:

We must receive comments on this proposed AD by December 13, 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.

For service information identified in this proposed AD, contact 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:

Technical Information: 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.

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

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 relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2004-19470; Directorate Identifier 2003-NM-268-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 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 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 on the Internet at http://dms.dot.gov,, or 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 indicating that severed tension ties at the fuselage frame joints at body stations (BS) 1120 and 1140 were found on a Model 747-400 series airplane. The cause of the severed ties was fatigue cracking due to incorrect splice plate installation during the manufacturing process. The splice plates that were installed were made of aluminum instead of steel. When the severed tension ties were found, the airplane had accumulated approximately 6,505 total flight cycles and 52,334 total flight hours. Inspection of another Model 747-400 series airplane revealed loose fasteners at the frame to tension tie joints. Loose fasteners in the joints increase the potential for fatigue cracking. That airplane had accumulated approximately 5,875 total flight cycles and 49,426 total flight hours. Inadequate installation procedures have been determined as the root cause of these incidents. Fatigue cracking of the fuselage frame to tension tie joints, if not found and fixed, could result in severing of the tension ties and consequent rapid decompression of the airplane fuselage.

The fuselage frame to tension tie joints on certain Model 747-100B SUD, -300, and -400D series airplanes are identical to those on the affected Model 747-400 series airplanes. Therefore, all of these models may be subject to the same unsafe condition.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 747-53-2483, Revision 1, dated August 28, 2003. The service bulletin describes procedures for a one-time detailed visual inspection for discrepancies (cracks; loose, missing, or damaged fasteners or collars) of the fuselage frame to tension tie joints at BS 1120 through 1220, and to determine if steel splice plates are installed on the fuselage frame, and related investigative and corrective actions. The investigative and corrective actions include performing an open-hole eddy current inspection of the fastener holes if loose, missing, or damaged fasteners or collars are found, and installing new fasteners if necessary.

The service bulletin also specifies that operators may contact the manufacturer for disposition of certain repair instructions, and recommends that the manufacturer be contacted if an aluminum splice plate is installed.

Accomplishing the actions specified in the service information is intended to 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 you to use the service information described previously to perform the actions, except as discussed under “Differences Between the Proposed AD and Service Bulletin.”

Differences Between the Proposed AD and Service Bulletin

The service bulletin provides the following information in Note 5 of the Accomplishment Instructions: “For the purposes of this service bulletin, do not count flight-cycles with a cabin pressure differential of 2.0 [pounds per square inch (psi)] or less. However, any flight-cycle with momentary spikes in cabin pressure differential above 2.0 psi must be included as a full-pressure flight-cycle. Cabin pressure records must be maintained for each airplane. Fleet averaging of cabin pressure is not allowed.” We have determined that an adjustment of flight cycles due to a lower cabin differential pressure is not substantiated and will not be allowed for use in determining the flight cycle threshold for this proposed AD.

The service bulletin also specifies that, if repair requirements exceed allowable repair criteria, operators may contact the manufacturer for disposition of repair instructions. This proposed AD would require operators to repair these conditions in accordance with a method approved by the FAA or in accordance with 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.

The service bulletin also recommends that the manufacturer be contacted for repair instructions if an aluminum splice plate is installed, but this proposed AD would require replacement of the plate with a new plate in accordance with a method approved by the FAA, or in accordance with 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 those findings.

The service bulletin specifies to submit certain information to the manufacturer, but this proposed AD does not include that requirement.

Although the service bulletin defines a “detailed visual” inspection for discrepancies, we have determined that the procedures in the service bulletin should be described as a “detailed inspection.” A note has been added to define that type of inspection.

Costs of Compliance

This proposed AD would affect about 67 airplanes of U.S. registry and 537 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 proposed AD for U.S. operators is $8,710, 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.