Airworthiness directives: Boeing,

[Federal Register: December 6, 1999 (Volume 64, Number 233)]

[Proposed Rules]

[Page 68058-68060]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr06de99-24]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-182-AD]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 767 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 767 series airplanes. This proposal would require repetitive inspections to detect fatigue cracking of the pitch load fittings of the wing front spar, and rework, if necessary. This proposal is prompted by a structural fatigue analysis that shows that the operational loads of the nacelle are higher than the loads used during initial design of the Model 767. The actions specified by the proposed AD are intended to detect and correct fatigue cracking in the pitch load fittings of the wing front spar, which could result in reduced structural integrity of the strut.

DATES: Comments must be received by January 20, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-182-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.

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: James G. Rehrl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2783; fax (425) 227-1181.

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 notice may be changed in light of the comments received.

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 filedin the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 99-NM-182-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. 99-NM-182-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report indicating that structural fatigue analysis on the Boeing Model 767 series airplane shows that the operational loads of the nacelle are higher than the loads used during initial design of the Boeing Model 767 series airplane. Higher operational loads could lead to fatigue cracking in the pitch load fittings of the wing front spar initiating earlier than expected. Structural assessment indicated that certain design changes would be needed on the strut-to-wing structure of the airplane to ensure that fatigue cracking would not occur during the Model 767 design service objective of 20 years or 50,000 flight cycles. Fatigue cracking of the pitch load fittings of the wing front spar, if not corrected, could result in reduced structural integrity of the strut.

Explanation of Relevant Service Information

The FAA has reviewed and approved Boeing Service Bulletin 767-57- 0053, Revision 2, dated September 23, 1999, which describes procedures for repetitive inspections to detect cracking of the pitch load fittings of the wing front spar, and rework, if necessary. The service bulletin describes procedures for two different methods for accomplishing an inspection. One method involves performing repetitive ultrasonic and eddy current inspections to detect cracking of the pitch load fittings. In lieu of that method, the service bulletin describes another inspection method that involves removing the upper link and performing a high frequency eddy current inspection to detect cracking of the pitch load fittings, and a detailed visual inspection to detect damage or corrosion of the inner and outer face pad-up areas of the pitch load fittings and to determine if the pad-up areas are parallel. The procedures for rework described in the service bulletin include reworking the inner or outer face of the pitch load fitting, reworking the lugs of the pitch load fittings, and installing new bushings. (The service bulletin describes two alternatives for installing the bushings.)

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 This Proposed AD and the Service Bulletin

Operators should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this proposed AD would require the repair of those conditions to be accomplished 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

[[Page 68059]]

who has been authorized by the FAA to make such findings.

Cost Impact

There are approximately 663 airplanes of the affected design in the worldwide fleet. The FAA estimates that 312 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 10 work hours per airplane to accomplish the proposed inspections, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the proposed inspections on U.S. operators is estimated to be $187,200, or $600 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 AD were not adopted.

Regulatory Impact

The regulations proposed herein would not have substantial direct effects 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, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

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.

   Sec. 39.13 [Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

   Boeing: Docket 99-NM-182-AD.

   Applicability: Model 767 series airplanes, line numbers 1 through 663 inclusive, certificated in any category.

   Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (g) 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 fatigue cracks in the pitch load fittings of the wing front spar, which could result in reduced structural integrity of the strut, accomplish the following:

   (a) Accomplish the requirements of either paragraph (b) or (c) of this AD at the later of the times specified in paragraphs (a)(1) and (a)(2) of this AD.

   (1) Prior to the initial inspection threshold specified in Figure 1, Table 1.1 of Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999.

   (2) Within 3,000 flight cycles or 18 months after the effective date of this AD, whichever occurs first.

   Note 2: Inspections and repairs accomplished prior to the effective date of this AD in accordance with Boeing Service Bulletin 767-57-0053, dated June 27, 1996; or Revision 1, dated October 31, 1996; are considered acceptable for compliance with the applicable action specified in this amendment.

   Option 1: Ultrasonic and Eddy Current Inspections

   (b) Perform ultrasonic and eddy current inspections to detect cracks of the pitch load fittings of the wing front spar, in accordance with Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999.

   (1) If no crack is detected, repeat the inspections thereafter at the interval specified in Table 1.2 of Figure 1 of the service bulletin.

   (2) If any crack is detected, prior to further flight, remove the upper link and the pitch load fitting bushings, and accomplish both paragraphs (b)(2)(i) and (b)(2)(ii) of this AD.

   (i) Perform a detailed visual inspection of the inner and outer face pad-up areas of the pitch load fittings to detect damage or corrosion and to determine if the pad-up areas are parallel, in accordance with the service bulletin. Except as provided by paragraph (f) of this AD, if any damage, corrosion, or non- parallelism is detected, prior to further flight, rework the inner or outer face of the pitch load fitting where damage or corrosion was detected, and make pad-up areas parallel, as applicable, in accordance with the service bulletin.

   (ii) Accomplish paragraph (d) of this AD.

   Note 3: 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.''

   Option 2: High Frequency Eddy Current and Detailed Visual Inspections

   (c) Remove the upper link and accomplish the requirements of paragraphs (c)(1) and (c)(2) of this AD, in accordance with Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999.

   (1) Perform a high frequency eddy current inspection to detect cracking of the pitch load fittings of the wing front spar.

   (2) Perform a detailed visual inspection of the inner and outer face pad-up areas of the pitch load fittings to detect damage or corrosion and to determine if the pad-up areas are parallel. Except as provided by paragraph (f) of this AD, if any damage, corrosion, or non-parallelism is detected, prior to further flight, rework the inner or outer face of the pitch load fitting where damage or corrosion was detected, and make pad-up areas parallel, as applicable, in accordance with the service bulletin.

   Rework

   (d) For airplanes on which any cracking is detected during any inspection required by paragraph (b) of this AD, or on which the requirements of paragraph (c) of this AD have been accomplished: Prior to further flight, accomplish paragraph (d)(1) or (d)(2) of this AD, as applicable, in accordance with Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999; and accomplish paragraph (e) of this AD.

   (1) For airplanes inspected in accordance with paragraph (c) of this AD and on which no cracking was detected: Make an insurance cut of the pitch load fitting lug.

   (2) For airplanes on which any cracking was detected during any inspection required by paragraph (b) or (c) of this AD: Except as provided by paragraph (f) of this AD, rework the lugs of the pitch load fittings of the wing front spar.

   Bushing Installation

   (e) For airplanes on which the requirements specified in paragraph (d) of this AD have been accomplished: Prior to further flight, install new bushings in the pitch load fittings of the wing front spar as

   [[Page 68060]]

   specified in paragraph (e)(1) or (e)(2) of this AD, in accordance with Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999.

   (1) Option 1: Install new bushings using the high interference fit method, and repeat the inspections required by paragraph (b) or (c) of this AD at the intervals specified in Table 1.3 of Figure 1. of the service bulletin.

   (2) Option 2: Install new bushings using the FORCEMATE method, and repeat the inspections required by paragraph (b) or (c) of this AD at the interval specified in Table 1.4 of Figure 1. of the service bulletin.

   (f) If any damage is detected that is outside the limits specified in Boeing Service Bulletin 767-57-0053, Revision 2, dated September 23, 1999, and the service bulletin specifies to contact Boeing for appropriate action: Prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate; 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, as required by this paragraph, the approval letter must specifically reference this AD.

   Alternative Methods of Compliance

   (g) 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, Transport Airplane Directorate. 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 4: 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

   (h) 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 November 30, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

   [FR Doc. 99-31476Filed12-3-99; 8:45 am]

   BILLING CODE 4910-13-U