04-21648. Airworthiness Directives; Boeing Model 747-100B SUD, -200B, -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, -200B, -300, -400, and -400D series airplanes. This proposed AD would require repetitive inspections for cracking in fuselage stringers 8L, 8R, 10L, and 10R at body stations 460, 480, and 500 frame locations; and repair if necessary. This proposed AD is prompted by findings of cracking in fuselage stringers 8L, 8R, 10L, and 10R at body stations 460, 480, and 500 frame locations. We are proposing this AD to detect and correct fatigue cracking in certain fuselage stringers which, if left undetected, could result in fuselage skin cracking that reduces the structural integrity of the skin panel, and consequent rapid depressurization of the airplane.

DATES:

We must receive comments on this proposed AD by November 12, 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: [phone].
• 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 may examine the AD docket, which contains the proposed AD, comments received, and any final disposition, on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT:

Nick Kusz, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

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-2004-19175; Directorate Identifier 2003-NM-246-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 may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may 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 may 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 [phone]) 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 reports of cracking at fuselage stringers 8L, 8R, 10L, and 10R at body station 460, 480, and 500 frame locations. These stringers are above and below the upper deck windows. The cracking was found on certain Boeing Model 747-100B SUD, -200B, -300, -400, and -400D series airplanes having stretched upper decks. Investigation revealed that the cracking was caused by fatigue. The affected airplanes had between 29,873 and 90,333 total flight hours and between 9,691 and 25,513 total flight cycles. If the fatigue cracking at the specified locations is not detected and corrected, the cracking could grow to include the fuselage skin along the window belt of the upper deck. Such cracking of the fuselage skin could result in reduced structural integrity of the skin panel, and consequent rapid depressurization of the airplane.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 747-53A2484, dated June 26, 2003. The service bulletin describes procedures for doing repetitive detailed visual inspections of fuselage stringers 8L, 8R, 10L, and 10R at body station 460, 480, and 500 frame locations and repairing areas with cracking. The repair procedures include installing new frame clips and new, additional stringer splices and doublers. For cracking that exceeds the specified limitations, the service bulletin specifies to install new sections of stringer in accordance with the 747 Structural Repair Manual along with incorporation of repair parts from the service bulletin. The service bulletin also describes an optional modification, which eliminates the need for the repetitive inspections. The optional modification includes procedures for installing new frame clips and new doublers; and repairing, as applicable. Accomplishing the actions specified in the service bulletin 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 repetitive inspections for fatigue cracking in fuselage stringers 8L, 8R, 10L, and 10R at body station 460, 480, and 500 frame locations; and repair if necessary. The proposed AD also would provide an optional terminating action for the repetitive inspections. 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 Information.”

Differences Between the Proposed AD and Service Information

The manufacturer reanalyzed the service problem and has advised the FAA that the reanalysis has resulted in threshold and repetitive inspection intervals different from the service bulletin. This resulted in simplified initial thresholds and an increased number of flight cycles between repetitive inspections. This difference has been coordinated with the manufacturer.

Clarification of Inspection Terminology

In this proposed AD, the “detailed visual inspection” specified in the Boeing service bulletin is referred to as a “detailed inspection.” We have included the definition for a “detailed inspection” in a note in this proposed AD.

Costs of Compliance

This proposed AD would affect about 243 Boeing Model 747-100B SUD, -200B, -300, -400, and -400D series airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.- registered airplanes	Fleet cost
Inspection	3	$65	None	$195	69	$13,455

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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2004-19175; Directorate Identifier 2003-NM-246-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by November 12, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to certain Boeing Model 747-100B SUD, -200B, -300, -400, and -400D series airplanes; certificated in any category; as listed in Boeing Alert Service Bulletin 747-53A2484, dated June 26, 2003.

Unsafe Condition

(d) This AD was prompted by findings of cracking in fuselage stringers 8L, 8R, 10L, and 10R at body station 460, 480, and 500 frame locations. We are proposing this AD to detect and correct fatigue cracking in the specified fuselage stringers which, if left undetected, could result in fuselage skin cracking that reduces the structural integrity of the skin panel, and consequent rapid depressurization of the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspection

(f) Do a detailed inspection for cracking in fuselage stringers 8L, 8R, 10L, and 10R at body station 460, 480, and 500 frame locations, in accordance with Part 1 of the Accomplishment Instructions in Boeing Alert Service Bulletin 747-53A2484, dated June 26, 2003. Do the inspections at the applicable time specified in paragraph (f)(1) or (f)(2) of this AD. Repeat the inspection thereafter at intervals not to exceed 3,000 flight cycles until the requirements of paragraph (h) of this AD are accomplished.

(1) For airplanes with 19,000 total flight cycles or less as of the effective date of this AD: Prior to the accumulation of 8,000 total flight cycles or within 2,000 flight cycles after the effective date of this AD, whichever is later, not to exceed 20,000 total flight cycles.

(2) For airplanes with more than 19,000 total flight cycles as of the effective date of this AD: Within 1,000 flight cycles after the effective date of this AD.

Note 1:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

Repair

(g) If any cracking is found during any inspection required by paragraph (f) of this AD: Before further flight, repair the affected stringer in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2484, dated June 26, 2003. Repair terminates the repetitive inspections required by paragraph (f) of this AD for only the repaired stringer/frame location.

Optional Terminating Action

(h) Installing new frame clips and new doublers; and repairing as applicable; in accordance with Part 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2484, dated June 26, 2003, terminates the repetitive inspections required by this AD.

Alternative Methods of Compliance (AMOCs)

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

Issued in Renton, Washington, on September 20, 2004.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.