02-13424. Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This proposal would require repetitive inspections to detect evidence of wear damage in the area at the interface between the vertical stabilizer and fuselage skin, and corrective actions, if necessary. This proposal also would provide for an optional terminating action for the repetitive inspections. This action is necessary to detect and correct wear damage of the fuselage skin, which could result in thinning and cracking of the fuselage skin, and consequent in-flight depressurization of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by July 15, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2002-NM-85-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 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. 2002-NM-85-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:

Technical Information: 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].

Other Information: Judy Golder, Airworthiness Directive Technical Editor/Writer; telephone [phone], fax [phone]. Questions or comments may also be sent via the Internet using the following address: [e-mail]. Questions or comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

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 2002-NM-85-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. 2002-NM-85-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received several reports of wear damage at the interface area of the vertical stabilizer and fuselage skin in section 46 and section 48 on certain Boeing Model 747 series airplanes. The damage has been attributed to movement of the adjacent vertical stabilizer blade seal and subsequent wear through the enamel coating on the fuselage skin. Such wear damage of the fuselage skin in the area at the interface between the vertical stabilizer and fuselage skin, if left undetected, could result in thinning and cracking of the fuselage skin, and consequent in-flight depressurization of the airplane.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Alert Service Bulletin (ASB) 747-53A2478, dated February 7, 2002, which describes procedures for repetitive detailed inspections to detect wear damage of the fuselage skin at the interface areas of the vertical stabilizer seal and fuselage skin, and corrective actions, if necessary. The ASB describes the corrective actions that include removal of the exterior surface finish and measurement of the wear depth if wear exists on the fuselage skin. If wear damage is detected, the ASB refers operators to the Structural Repair Manual (SRM). If no wear damage is found, the ASB describes procedures for refinishing the fuselage skin with BMS 10-86 Teflon-filled coating, which would eliminate the need for repetitive inspections. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

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 require accomplishment of the actions specified in the service bulletin described previously.

Cost Impact

There are approximately 1,104 Boeing Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 253 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 1 work hour per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators is estimated to be $15,180, or $60 per airplane, per inspection cycle.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed 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.

Should an operator elect to accomplish the proposed optional terminating action per paragraph (b) of this AD, it would take approximately 6 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 optional termination action would be $360 per airplane.

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 adding the following new airworthiness directive:

Boeing: Docket 2002-NM-85-AD.

Applicability: Model 747 series airplanes, as listed in Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002; 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 (c) 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 wear damage of the fuselage skin in the area at the interface between the vertical stabilizer and fuselage skin, which could result in thinning and cracking of the fuselage skin, and consequent in-flight depressurization of the airplane; accomplish the following:

Inspections for Damage

(a) Prior to the accumulation of 15,000 total flight cycles or within 1,200 flight cycles after the effective date of this AD, whichever occurs later: Perform a detailed inspection to detect evidence of wear damage of the fuselage skin at the interface area of the vertical stabilizer seal and fuselage skin, per Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002.

(1) If no wear damage of the fuselage skin is detected or any existing blendout is within the structural repair manual (SRM) allowable damage limits: Repeat the detailed inspection at intervals not to exceed 6,000 flight cycles.

(2) If any wear damage of the fuselage skin is detected or any existing blendout exceeds the allowable damage limits specified in the SRM: Before further flight, repair the vertical stabilizer seal interface and refinish the skin with BMS 10-86 Teflon filled coating, per the alert service bulletin. Accomplishment of the repair and refinishing is terminating action for the repetitive inspections required by paragraph (a) of this AD.

Note 2:

For the purposes of this AD, a detailed 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.”

Optional Terminating Action

(b) Refinishing the fuselage skin with BMS 10-86 Teflon-filled coating, per Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002, terminates the repetitive inspections required by paragraph (a) of this AD.

Alternative Methods of Compliance

(c) 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 Aircraft Certification Office (ACO), FAA. 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.

Note 3:

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

(d) Special flight permits may be issued in accordance with sections 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 22, 2002.

Ali Bahrami,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.