Airworthiness directives: Boeing,

[Federal Register: October 18, 1999 (Volume 64, Number 200)]

[Rules and Regulations]

[Page 56151-56155]

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

[DOCID:fr18oc99-6]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-363-AD; Amendment 39-11363; AD 99-21-18]

RIN 2120-AA64

Airworthiness Directives; Boeing Model 767 Series Airplanes Powered by Pratt & Whitney JT9D-7R4 Series Turbofan Engines or General Electric CF6-80A Series Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

SUMMARY: This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that requires repetitive inspections to detect certain discrepancies of the cables, fittings, and pulleys of the engine thrust control cables; and repair, if necessary. For certain airplanes, this amendment also requires replacement of certain pulleys with new pulleys, and re-rigging of the engine thrust control cable. This amendment is prompted by reports of engine thrust control cable failures. The actions specified by this AD are intended to prevent such failures, which could result in a severe asymmetric thrust condition during landing, and consequent reduced controllability of the airplane.

DATES: Effective November 22, 1999.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of November 22, 1999.

ADDRESSES: The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Holly Thorson, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1357; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Boeing Model 767 series airplanes was published in the Federal Register on April 14, 1999 (64 FR 18386). That action proposed to require modification of the engine thrust control cable installation; repetitive inspections to detect certain discrepancies of the cables, pulleys, pulley brackets, and cable travel; and repair, if necessary. For certain airplanes, that action also proposed to require replacement of certain pulleys with new pulleys, and re-rigging of the engine thrust control cable.

Comments

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.

Support for the Proposal

One commenter supports the proposed AD.

Request for Clarification on Allowable Part Numbers

One commenter requests clarification on which part numbers of aluminum pulleys will satisfy the intent of paragraph (b) of the proposed AD. This commenter states that it has accomplished Boeing Service Bulletin 767-76-0010, dated April 19, 1985, on its fleet. That bulletin specifies replacement of the non-metallic pulleys of the engine thrust control cable that are located in the leading edge of the wing adjacent to the left and right engine strut, with aluminum pulleys having the part number 255T1232-1. The proposed AD would require pulleys to be replaced in accordance with Boeing Service Bulletin 767- 76-0010, Revision 1, dated February 20, 1992. That bulletin specifies that replacement with aluminum pulleys having the part number 255T1232- 3 is preferred, but use of aluminum pulleys having the part number 255T1232-1 is allowed. The commenter states that, if aluminum pulleys having the part number 255T1232-3 are the only approved pulleys, the lack of availability of that pulley may cause unplanned delays in the accomplishment of the proposed AD.

The FAA intends that paragraph (b) of this AD require replacement of non-metallic pulleys of the engine thrust control cable that are located in the leading edge of the wing adjacent to the left and right engine strut, with aluminum pulleys having the part number 255T1232-1 or -3. Pulleys having the part number 255T1232-3 are preferred because they use a different bearing that has high temperature grease. After reviewing Boeing Service Bulletin 767-76-0010, dated April 19, 1985, the FAA finds that accomplishment of the replacement specified in that service bulletin is acceptable for compliance with the replacement required by paragraph (b) of the final rule; therefore, a note stating this has been added to the final rule.

Request for Information on Other Relevant Rulemaking

One commenter notes that the proposed rule states that the damage criteria in Appendix 1., ``Thrust Control Cable Inspection Procedure,'' is based on the requirements in the Boeing 757 Maintenance Manual, which are more stringent than the requirements for the Model 767 series airplane. The commenter requests information regarding similar rulemaking for the Boeing Model 757 series airplane. No specific change to the rule is requested.

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The FAA has issued two proposed rules to address the unsafe condition on other Boeing airplane models that have an engine thrust control cable installation similar to the Model 767 series airplane:

‹bullet› FAA Rules Docket No. 98-NM-323-AD (64 FR 49105, September 10, 1999), which applies to certain Model 757-200 series airplanes; and

‹bullet› FAA Rules Docket No. 99-NM-22-AD (64 FR 53275, October 1, 1999), which applies to certain Model 747 series airplanes.

No change to the final rule is necessary in this regard.

Request for Extension of the Compliance Time

Two commenters request that the compliance time for the repetitive inspections specified in paragraph (a) of the proposed AD be extended. One commenter suggests that its inspection program, which specifies inspection of different sections of the engine thrust control cable installation at intervals from 2,600 flight hours to 9,000 flight hours, including inspections of certain sections to be performed only on a sampling of airplanes in an operator's fleet, is adequate. Therefore, reducing the interval by 50 percent, as specified in the proposed AD, is unnecessary. The other commenter suggests that the engine thrust control cables be inspected at every ``2C'' check, with certain sections of the cable run to be inspected at every ``C'' check. (This commenter considers a ``C'' check interval to be 456 days.) This commenter states that it will have to modify its maintenance program to accomplish the proposed repetitive inspections every 18 months or 4,500 flight hours.

The FAA does not concur with the commenters' request to extend the compliance time. There has been one engine thrust control cable failure on a Model 767 series airplane, and two failures on Model 757 series airplanes. (The engine thrust control cable installation on certain Model 757 series airplanes is similar to that on certain Model 767 series airplanes.) There was no evidence in these events that the operators were not following the Boeing maintenance planning document recommendations for the engine thrust control cable inspections. Given this experience and the possibly catastrophic effect of a thrust control cable failure, the FAA has determined that it is necessary to conduct more frequent inspections of the cable installations. Therefore, this AD requires the engine thrust control cable inspections to be accomplished every 18 months or 4,500 flight hours, whichever occurs first. No change to the final rule is necessary in this regard.

Request for Clarification of Applicability

One commenter requests clarification of the applicability of the proposed AD. The commenter states that this proposed AD affects Model 767 series airplanes powered by Pratt & Whitney JT9D series turbofan engines, and Model 767 series airplanes powered by General Electric CF6 series turbofan engines that do not use full authority digital electronic controls (FADEC).

The FAA concurs partially. This AD only affects certain Model 767 series airplanes powered by General Electric CF6 series turbofan engines that do not use FADEC (as well as Model 767 series airplanes powered by Pratt & Whitney JT9D series turbofan engines). Specifically, this AD affects Model 767 series airplanes powered by CF6-80A series turbofan engines. The engine thrust control cable installation is different on airplanes powered by other General Electric CF6 series turbofan engines that do not use FADEC, and the unsafe condition discussed previously does not exist on those airplanes. Therefore, no change to the final rule is necessary in this regard.

Explanation of Changes Made to the Cost Impact

The FAA has been advised that the replacement of pulleys required by paragraph (b) of this AD has been accomplished on 23 airplanes of U.S. registry. Accordingly, the FAA has revised the cost impact, below, to reflect this information.

Explanation of Changes Made to Appendix 1

Prompted by two comments received to FAA Rules Docket No. 98-NM- 323-AD (64 FR 7822, February 17, 1999), which proposed actions similar to those required by this AD for the Model 757 series airplane, the FAA reviewed Appendix 1., ``Thrust Control Cable Inspection Procedure,'' of the proposed AD. One commenter to FAA Rules Docket No. 98-NM-323-AD stated that the proposed procedure would require disassembly of the engine thrust control cable installation. The other commenter suggested that the procedure be revised to eliminate all steps that do not contribute to the intent of the AD.

In FAA Rules Docket No. 98-NM-323-AD (the FAA issued a supplemental NPRM for reasons other than the inspection procedure), the FAA concurred with the commenters' request to revise the inspection procedure. The FAA's intent was to define a thorough inspection of the engine thrust control cable installation while minimizing the amount of disruptive maintenance to the installation. With technical input from the airplane manufacturer, an improved and simplified inspection procedure has been developed, and Appendix 1. of this AD has been revised accordingly. Figure 2 of Appendix 1. has been removed because it is no longer needed for the inspection. The FAA has determined that the revision, although extensive, does not change the intent of the proposed procedure and actually decreases the scope of the inspection. In addition, the FAA has revised certain language in the preamble of this AD to reflect the changes to Appendix 1.

In addition, the FAA has corrected the summary of the final rule. The summary of the proposed AD stated a modification of the engine thrust control cable installation would be required on all affected airplanes. No such requirement was included in the proposed AD.

Conclusion

After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes previously described. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact

There are approximately 211 airplanes of the affected design in the worldwide fleet. The FAA estimates that 100 airplanes of U.S. registry will be affected by this AD.

For all airplanes (100 U.S.-registered airplanes), it will take approximately 3 work hours per airplane to accomplish the required inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the inspection required by this AD on U.S. operators is estimated to be $18,000, or $180 per airplane, per inspection cycle.

For airplanes identified in Boeing Service Bulletin 767-76-0010, Revision 1 (52 U.S.-registered airplanes), it will take approximately 9 work hours per airplane to accomplish the required replacement and re- rigging, at an average labor rate of $60 per work hour. Required parts will cost $484 per airplane. Based on these figures, the cost impact of the replacement and re-rigging required by this AD on U.S. operators is estimated to be $53,248, or $1,024 per airplane. The cost impact figures

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discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. However, the FAA has been advised that 23 airplanes of U.S. registry have been modified in accordance with Boeing Service Bulletin 767-76-0010, Revision 1, as required by paragraph (b) of this AD. Therefore, the future economic cost impact of the required replacement and re-rigging on U.S. operators is now only $29,696, or $1,024 per airplane.

Regulatory Impact

The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends 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:

   99-21-18 Boeing: Amendment 39-11363. Docket 98-NM-363-AD.

   Applicability: Model 767 series airplanes powered by Pratt & Whitney JT9D-7R4 series turbofan engines or General Electric CF6-80A series turbofan engines, 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 prevent engine thrust control cable failure, which could result in a severe asymmetric thrust condition during landing, and consequent reduced controllability of the airplane, accomplish the following:

   (a) For all airplanes: Within 18 months or 4,500 flight hours after the effective date of this AD, whichever occurs first, accomplish the ``Thrust Control Cable Inspection Procedure'' specified in Appendix 1 (including Figure 1) of this AD to verify the integrity of the thrust control cables. Prior to further flight, repair any discrepancy found, in accordance with the procedures described in the Boeing 767 Maintenance Manual. Repeat the inspection thereafter at intervals not to exceed 18 months or 4,500 flight hours, whichever occurs first.

   (b) For airplanes identified in Boeing Service Bulletin 767-76- 0010, Revision 1, dated February 20, 1992: Within 18 months or 4,500 flight hours after the effective date of this AD, whichever occurs first, replace the two non-metallic pulleys of the thrust control cable that are located in the leading edge of the wing adjacent to the left and right engine strut with aluminum pulleys; and re-rig the thrust control cables; in accordance with the service bulletin.

   Note 2: Accomplishment of the replacement specified in Boeing Service Bulletin 767-76-0010, dated April 19, 1985, is acceptable for compliance with the replacement required by paragraph (b) 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, 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 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.

   Incorporation by Reference

   (e) The replacement and re-rigging specified in paragraph (b) of this AD shall be done in accordance with Boeing Service Bulletin 767-76-0010, Revision 1, dated February 20, 1992. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

   (f) This amendment becomes effective on November 22, 1999.

   Appendix 1.--Thrust Control Cable Inspection Procedure

1. General

   1. Clean the cables, if necessary, for the inspection, in accordance with Boeing 767 Maintenance Manual 12-21-31.

   2. Use these procedures to verify the integrity of the thrust control cable system. The procedures must be performed along the entire cable run for each engine. To ensure verification of the portions of the cables which are in contact with pulleys and quadrants, the thrust control must be moved by operation of the thrust and/or the reverse thrust levers to expose those portions of the cables.

   3. The first task is an inspection of the control cable wire rope. The second task is an inspection of the control cable fittings. The third task is an inspection of the pulleys.

   Note: These three tasks may be performed concurrently at one location of the cable system on the airplane, if desired, for convenience.

   Note: For the purposes of this procedure, 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.''

2. Inspection of the Control Cable Wire Rope

   1. Perform a detailed visual inspection to ensure that the cable does not contact parts

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      other than pulleys, quadrants, cable seals, or grommets installed to control the cable routing. Look for evidence of contact with other parts. Correct the condition if evidence of contact is found.

   2. Perform a detailed visual inspection of the cable runs to detect incorrect routing, kinks in the wire rope, or other damage. Replace the cable assembly if:

      (1) One cable strand had worn wires where one wire cross section is decreased by more than 40 percent (see Figure 1),

      (2) A kink is found, or

      (3) Corrosion is found.

   3. Perform a detailed visual inspection of the cable: To check for broken wires, rub a cloth along the length of the cable. The cloth catches on broken wires.

      (1) Replace the 7x7 cable assembly if there are two or more broken wires in 12 continuous inches of cable or there are three or more broken wires anywhere in the total cable assembly.

      (2) Replace the 7x19 cable assembly if there are four or more broken wires in 12 continuous inches of cable or there are six or more broken wires anywhere in the total cable assembly.

3. Inspection of the Control Cable Fittings

   1. Perform a detailed visual inspection to ensure that the means of locking the joints are intact (wire locking, cotter pins, turnbuckle clips, etc.). Install any missing parts.

   2. Perform a detailed visual inspection of the swaged portions of swaged end fitting to detect surface cracks or corrosion. Replace the cable assembly if cracks or corrosion are found.

   3. Perform a detailed visual inspection of the unswaged portion of the end fitting. Replace the cable assembly if a crack is visible, if corrosion is present, or if the end fitting is bent more than 2 degrees.

   4. Perform a detailed visual inspection of the turnbuckle. Replace the turnbuckle if a crack is visible or if corrosion is present.

4. Inspection of Pulleys

   1. Perform a detailed visual inspection to ensure that pulleys are free to rotate. Replace pulleys which are not free to rotate.

   BILLING CODE 4910-13-P

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   [GRAPHIC] [TIFF OMITTED] TR18OC99.000

   Issued in Renton, Washington, on October 4, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

   [FR Doc. 99-26568Filed10-15-99; 8:45 am]

   BILLING CODE 4910-13-C