02-22130. Airworthiness Directives; Boeing Model 747 Series Airplanes Powered by General Electric (GE) CF6-80C2 Series Engines

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 powered by GE CF6-80C2 series engines. This proposal would require repetitive inspections and torque checks to find discrepancies of the fasteners that attach the diagonal brace fittings of the lower spar to the inboard engine struts, and modification of the fasteners if discrepancies are found. This proposal also would require eventual modification of all the fasteners, which would end the repetitive inspections and checks. This action is necessary to find and fix discrepant fasteners of the diagonal brace fittings, which could result in reduced structural integrity of the diagonal brace-to-strut attachment, and possible separation of the strut and engine from the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by October 15, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2001-NM-17-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 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. 2001-NM-17-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: Tamara Anderson, 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: Sandi Carli, 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.

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 2001-NM-17-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. 2001-NM-17-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received reports indicating that, during installation of the modification required by AD 95-13-06 (described below), loose and fractured fasteners of the diagonal brace fitting were found on certain Boeing Model 747 series airplanes powered by GE CF6-80C2 series engines. The cause of the fastener discrepancies was determined to be fatigue. The diagonal brace fitting of the lower spar is located at the lower aft end of the strut and provides the structural attachment of the strut to the diagonal brace. The fasteners attach the fitting to the inboard strut. Cracking of the fitting or surrounding structure due to loose and/or fractured fasteners could lead to the loss of the diagonal brace-to-strut attachment and possible loss of the strut and engine from the airplane.

Other Relevant Rulemaking

On June 16, 1995, we issued AD 95-13-06, amendment 39-9286 (60 FR 33338, June 28, 1995). That AD applies to certain Boeing Model 747 series airplanes equipped with General Electric CF6-80C2 series engines or Pratt & Whitney Model PW4000 series engines. That AD requires modification of the nacelle strut and wing structure, inspections and checks to detect discrepancies, and correction of discrepancies.

Explanation of Relevant Service Information

We have reviewed and approved Boeing Alert Service Bulletin 747-54A2207, dated November 16, 2000, which describes procedures for repetitive inspections and rotational checks (torque checks) to find discrepancies of the fasteners that attach the diagonal brace fittings of the lower spar to the inboard engine struts, and modification of the fasteners if discrepancies (loose, fractured, missing fastener heads) are found. Doing the modification eliminates the need for the repetitive inspections and checks. The modification includes doing a high frequency eddy current inspection (HFEC) of the fastener holes where discrepant fasteners are found and other indicated fastener holes, oversizing the holes, and installing new fasteners. The service bulletin specifies to contact Boeing if cracking is found during the HFEC inspection. 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, except as discussed below.

Differences Between the Service Bulletin and This Proposed AD

The service bulletin does not provide a compliance time for accomplishing the modification, but the proposed AD would require that the modification be accomplished within 72 months after the effective date of this AD. In developing an appropriate compliance time for this proposed AD, we considered not only the manufacturer's recommendation, but also the degree of urgency associated with addressing the unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the modification. In light of all of these factors, we find a 72-month compliance time for completing the required modification to be warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety.

Although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repairs, this proposed AD would require such repairs to be accomplished per a method approved by us, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who we have authorized to make such findings.

Cost Impact

There are approximately 237 airplanes of the affected design in the worldwide fleet. We estimate that 14 airplanes of U.S. registry would be affected by this proposed AD.

It would take approximately 5 work hours per airplane to accomplish the proposed inspection and torque check at an average labor rate of $60 per work hour. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $4,200, or $300 per airplane, per inspection/check cycle.

It would take approximately 76 work hours per airplane to accomplish the proposed terminating action at an average labor rate of $60 per work hour. Required parts would cost approximately $4,268 per airplane. Based on these figures, the cost impact of this proposed action on U.S. operators is estimated to be $123,592, or $8,828 per airplane.

The cost impact figures discussed above are 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.

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 2001-NM-17-AD.

Applicability: Model 747-200B, -300, -400, -400D, and -400F series airplanes powered by GE CF6-80C2 series engines, as listed in Boeing Alert Service Bulletin 747-54A2207, dated November 16, 2000, 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 (d) 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 find and fix discrepant fasteners of the diagonal brace fittings, which could result in reduced structural integrity of the diagonal brace-to-strut attachment, and possible separation of the strut and engine from the airplane, accomplish the following:

Repetitive Inspections and Torque Checks/Corrective Action

(a) Do a detailed inspection and torque check to find discrepancies of the fasteners (e.g., loose, fractured, or missing fastener heads) that attach the diagonal brace fittings of the lower spar to the inboard engine struts, at the applicable time specified in paragraph (a)(1) or (a)(2) of this AD, per Boeing Alert Service Bulletin 747-54A2207, dated November 16, 2000. Repeat the inspection and check after that every 8,000 flight hours or 24 months, whichever is first.

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.”

(1) For airplanes that have not been modified as required by AD 95-13-06, amendment 39-9286 (all Group 2 airplanes): Before the accumulation of 6,000 total flight cycles or within 24 months after the effective date of this AD, whichever is later.

(2) For airplanes that have been modified as required by AD 95-13-06 (all Group 1 airplanes): Before the accumulation of 6,000 total flight cycles after doing the modification or within 24 months after the effective date of this AD, whichever is later.

(b) If no discrepancy is found during any inspection/check required by paragraph (a) of this AD, repeat the inspection/check at the time specified in paragraph (a) of this AD until the terminating action specified in paragraph (c) of this AD is done. If any discrepancy is found, do the applicable actions specified in paragraph (b)(1) or (b)(2) of this AD.

(1) If any discrepancy is found in the area that connects the diagonal brace fitting to the aft bulkhead, before further flight, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per 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, as required by this paragraph, the approval must specifically reference this AD.

(2) If any discrepancy is found in any area other than that specified in paragraph (b)(1) of this AD, before further flight, do the terminating action specified in paragraph (c) of this AD.

Terminating Action

(c) Except as provided by paragraph (b)(2) of this AD, within 72 months after the effective date of this AD: Do the modification (including doing a high frequency eddy current (HFEC) inspection, oversizing the fastener holes, and installing new fasteners) as specified in and per Figure 3 of the Accomplishment Instructions of Boeing Alert Service Bulletin 747-54A2207, dated November 16, 2000. If any cracking is found during the HFEC inspection and the service bulletin specifies contacting Boeing for repair procedures, before further flight, repair per a method approved by the Manager, Seattle ACO; or per data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, as required by this paragraph, the approval must specifically reference this AD. Accomplishment of the actions specified in this paragraph ends the repetitive inspections and checks.

Alternative Methods of Compliance

(d) 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.

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 Permit

(e) 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 August 20, 2002.

Vi L. Lipski,

Manager, Transport Airplane Directorate, Aircraft Certification Service.