01-14043. Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to all Boeing Model 747 series airplanes, that currently requires a one-time inspection of the fuselage skin adjacent to the drag splice fitting to detect cracking, and follow-on actions, if necessary. This action would mandate new repetitive inspections for cracking of the fuselage skin adjacent to the drag splice fitting. This proposal is prompted by reports of fatigue cracking in the fuselage skin and adjacent structure. The actions specified by the proposed AD are intended to detect and correct such cracking, which could result in reduced structural integrity of the fuselage, and consequent rapid depressurization of the airplane.

DATES:

Comments must be received by July 20, 2001.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-220-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Rick Kawaguchi, 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:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

• Submit comments using the following format:
• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-220-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-220-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On July 3, 2000, the FAA issued AD 2000-14-04, amendment 39-11813 (65 FR 43219, July 13, 2000), applicable to all Boeing Model 747 series airplanes, to require a one-time inspection of the fuselage skin adjacent to the drag splice fitting to detect cracking, and follow-on actions, if necessary. The requirements of that AD are intended to detect and correct fatigue cracking of the fuselage skin, which could result in reduced structural integrity of the fuselage, and consequent rapid depressurization of the airplane.

Actions Since Issuance of Previous Rule

In the preamble to AD 2000-14-04, the FAA specified that the actions required by that AD were considered “interim action” and that the FAA was considering a separate rulemaking action to address the procedures for repetitive ultrasonic, high frequency eddy current, and detailed visual inspections of the fuselage skin adjacent to the drag splice fitting to detect additional cracking, and repair of any cracking detected, as described in Boeing Service Bulletin 747-53A2444, Revision 1, dated June 15, 2000 (which was referenced as the appropriate source of service information in that AD). The FAA now has determined that further rulemaking action is indeed necessary, and this proposed AD follows from that determination.

New Service Information

Since the issuance of AD 2000-14-04, the FAA has received a report of severe cracking on a Model 747 series airplane at approximately 14,540 flight cycles. In light of this report, the FAA has reviewed and approved Boeing Alert Service Bulletin 747-53A2444, Revision 2, dated May 24, 2001. Revision 2 is essentially the same as Revision 1 of the service bulletin, but Revision 2 specifies more comprehensive repetitive inspection procedures and reduces the compliance times specified in Revision 1. Revision 2 also references a procedure in the 747 Structural Repair Manual for the repair of certain cracking without further FAA approval.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 2000-14-04 to continue to require a one-time inspection of the fuselage skin adjacent to the drag splice fitting to detect cracking, and follow-on actions, if necessary. This proposed AD also mandates new repetitive inspections for cracking of the fuselage skin adjacent to the drag splice fitting.

Differences Between Alert Service Bulletin and This Proposed AD

The service bulletin references the 747 Structural Repair Manual (SRM) Subject 53-30-03, Figure 60, as an appropriate source of service information for accomplishment of the repair of the fuselage skin. Certain revisions to this chapter of the 747 SRM allow the use of 7075-T6 aluminum as an option for skin replacement when accomplishing the repair on the fuselage skin. Because 7075-T6 aluminum is significantly less durable than 2024-T3 aluminum, the FAA has determined that use of 7075-T6 as a repair material cannot be allowed. Future repairs of the subject area that require skin replacement may only use the 2024-T3 material. Existing repairs of the subject area already made from 7075-T6 aluminum will require follow-on inspections accomplished in a manner approved by the FAA.

Although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposal would require the repair of those conditions to be accomplished per a method approved by 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 Manager, Seattle Aircraft Certification Office, to make such findings.

Interim Action

This is interim action. The manufacturer has advised that it is developing a modification that will positively address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, the FAA may consider additional rulemaking.

Cost Impact

There are approximately 1,301 airplanes of the affected design in the worldwide fleet. The FAA estimates that 260 airplanes of U.S. registry would be affected by this proposed AD.

The actions that are currently required by AD 2000-14-04 take approximately 2 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $31,200, or $120 per airplane.

The new inspections that are proposed in this AD action would take approximately 7 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the new proposed requirements of this AD on U.S. operators is estimated to be $109,200, or $420 per airplane, per inspection cycle.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the current or proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein 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. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that 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) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (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. Section 39.13 is amended by removing amendment 39-11813 (65 FR 43219, July 13, 2000), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2000-NM-220-AD. Supersedes AD 2000-14-04, Amendment 39-11813.

Applicability: All Model 747 series airplanes, certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To detect and correct fatigue cracking of certain areas of the fuselage skin, which could result in reduced structural integrity of the fuselage, and consequent rapid depressurization of the airplane; accomplish the following:

Restatement of Requirements of AD 2000-14-04

One-Time Detailed Visual Inspection

(a) Prior to the accumulation of 13,000 total flight cycles or within 60 days after July 28, 2000 (the effective date of AD 2000-14-04, amendment 39-11813), whichever occurs later: Perform a one-time external detailed visual inspection of the fuselage skin adjacent to the drag splice fitting as illustrated in Figure 2 of Boeing Service Bulletin 747-53A2444, Revision 1, dated June 15, 2000. If no cracking is detected, no further action is required by this paragraph.

Note 2:

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

Corrective Action

(b) If any cracking is detected during any inspection required by this AD, prior to further flight, repair in accordance with Boeing Alert Service Bulletin 747-53A2444, Revision 2, dated May 24, 2001. Where the service bulletin specifies to contact Boeing for repair instructions, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.

Note 3:

Repairs accomplished prior to the effective date of this AD in accordance with a method approved by the Manager, Seattle ACO, FAA, or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER, are considered acceptable for compliance with the repair specified in paragraph (b) of this AD.

Note 4:

Boeing Alert Service Bulletin 747-53A2444, Revision 2, dated May 24, 2001, references the 747 Structural Repair Manual (SRM) as an appropriate source of service information for accomplishment of the repair of the fuselage skin. However, the use of 7075-T6 aluminum as specified in certain revisions of the SRM is not an option for skin replacement when accomplishing the subject repair.

Secondary Inspection

(c) For airplanes on which cracking is detected during any inspection required by paragraph (a) or (d) of this AD, prior to further flight after accomplishment of paragraph (b) of this AD: Determine if a secondary inspection of adjacent structure is required, using the Logic Diagram illustrated in Figure 1 of Boeing Service Bulletin 747-53A2444, Revision 1, dated June 15, 2000, or Boeing Alert Service Bulletin 747-53A2444, Revision 2, dated May 24, 2001. If required, before further flight, accomplish the inspection in accordance with the service bulletin.

Note 5:

Inspections and repairs accomplished prior to July 28, 2000, in accordance with Boeing Alert Service Bulletin 747-53A2444, dated May 25, 2000, are considered acceptable for compliance with the applicable actions specified in this amendment.

New Requirements of This AD

Repetitive Inspections

(d) Perform ultrasonic, high frequency eddy current, and detailed visual inspections in accordance with the Work Instructions of Boeing Alert Service Bulletin 747-53A2444, Revision 2, dated May 24, 2001, at the applicable times specified in Figure 1 of the Logic Diagram of the service bulletin; except where the compliance time in the logic diagram specifies an interval of “after the release date of the service bulletin,” this AD requires compliance within the interval specified in the service bulletin “after the effective date of this AD.” Repeat the applicable inspections at the intervals shown in Figure 1 of the Logic Diagram of the service bulletin. Accomplishment of the inspections required by this paragraph ends the inspections required by paragraph (a) of this AD.

Note 6:

Where there are differences between the AD and the service bulletin, the AD prevails.

Alternative Methods of Compliance

(e)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 2000-14-04, amendment 39-11813, are approved as alternative methods of compliance with this AD.

Note 7:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(f) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on May 30, 2001.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.