AD 95-13-12 R1

This amendment clarifies information in an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires tests, inspections, and adjustments of the thrust reverser system. That AD also requires installation of a terminating modification and repetitive follow-on actions. The actions specified in that AD are intended to prevent possible discrepancies that exist in the current thrust reverser control system, which could result in inadvertent deployment of a thrust reverser during flight. This amendment clarifies the requirements of the current AD by specifying a revised number of pound-inches of torque operators should use when performing the torque check of the cone brake of the center drive unit (CDU). This amendment is prompted by information from the manufacturer that a current requirement of the AD requires clarification.

Final rule; correction

95-13-12 R1 BOEING: Amendment 39-9528. Docket 94-NM-28-AD. Revises AD 95-13-12, Amendment 39-9292, which superseded AD 91-22-02, Amendment 39-8062.\n\n\tApplicability: Model 767 series airplanes equipped with General Electric CF6-80C2 series engines, certificated in any category.\n\n\tNOTE 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 use the authority provided in paragraph (f) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo ensure the integrity of the fail-safe features of the thrust reverser system, accomplish the following:\n\n\t(a)\tWithin 30 days after October 15, 1991 (the effective date of AD 91-22-02, amendment 39-8062), perform tests, inspections, and adjustments of the thrust reverser system in accordance with Boeing Service Bulletin 767-78-0047, dated August 22, 1991; Revision 1, dated March 26, 1992; Revision 2, dated January 21, 1993; or Revision 3, dated July 28, 1994. After the effective date of this AD, those actions shall be accomplished only in accordance with Revision 3 of the service bulletin.\n\n\t\t(1)\tExcept as provided by paragraph (a)(2) of this AD, repeat all tests and inspections thereafter at intervals not toexceed 3,000 flight hours until the modification required by paragraph (c) of this AD is accomplished.\n\n\t\t(2)\tRepeat the check of the grounding wire for the Directional Pilot Valve (DPV) of the thrust reverser in accordance with the service bulletin at intervals not to exceed 1,500 flight hours, and whenever maintenance action is taken that would disturb the DPV grounding circuit, until the modification required by paragraph (c) of this AD is accomplished.\n\n\t(b)\tIf any of the tests and/or inspections required by paragraph (a) of this AD cannot be successfully performed, or if those tests and/or inspections result in findings that are unacceptable in accordance with Boeing Service Bulletin 767-78-0047, dated August 22, 1991; Revision 1, dated March 26, 1992; Revision 2, dated January 21, 1993; or Revision 3, dated July 28, 1994; accomplish paragraphs (b)(1) and (b)(2) of this AD. After the effective date of this AD, the actions required by paragraphs (b)(1) and (b)(2) shall be accomplished only in accordance with Revision 3 of the service bulletin.\n\n\t\t(1)\tPrior to further flight, deactivate the associated thrust reverser in accordance with Section 78-31-1 of Boeing Document D630T002, "Boeing 767 Dispatch Deviation Guide," Revision 9, dated May 1, 1991; or Revision 10, dated September 1, 1992. After the effective date of this AD, this action shall be accomplished only in accordance with Revision 10 of the Boeing document. No more than one reverser on any airplane may be deactivated under the provisions of this paragraph.\n\n\t\t(2)\tWithin 10 days after deactivation of any thrust reverser in accordance with this paragraph, the thrust reverser must be repaired in accordance with Boeing Service Bulletin 767-78-0047, dated August 22, 1991; Revision 1, dated March 26, 1992; Revision 2, dated January 21, 1993; or Revision 3, dated July 28, 1994. After the effective date of this AD, the repair shall be accomplished only in accordance with Revision 3 of the service bulletin. Additionally, the tests and/or inspections required by paragraph (a) of this AD must be successfully accomplished; once this is accomplished, the thrust reverser must then be reactivated.\n\n\t(c)\tWithin 3 years after the effective date of this AD, install a third locking system on the left- and right-hand engine thrust reversers in accordance with Boeing Service Bulletin 767-78-0063, Revision 2, dated April 28, 1994.\n\n\tNOTE 2: The Boeing service bulletin references General Electric Service Bulletin 78-135 as an additional source of service information for accomplishment of the third locking system on the thrust reversers. However, the Boeing service bulletin does not specify the appropriate revision level for the General Electric service bulletin. The appropriate revision level for the General Electric service bulletin to be used in conjunction with the Boeing service bulletin is Revision 3, dated August 2, 1994.\n\n\t(d)\tWithin 4,000 flight hours after accomplishing themodification required by paragraph (c) of this AD, or within 4,000 flight hours after the effective date of this AD, whichever occurs later; and thereafter at intervals not to exceed 4,000 flight hours; perform operational checks of the electro-mechanical brake and the cone brake of the center drive unit in accordance with Appendix 1 (including Figure 1) of this AD.\n\n\t(e)\tAccomplishment of the modification and periodic operational checks required by paragraphs (c) and (d) of this AD constitutes terminating action for the tests, inspections, and adjustments required by paragraph (a) of this AD.\n\n\t(f)\tAn 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.\n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.\n\n\t(g)\tSpecial 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.\n\n\t(h)\tCertain actions shall be done in accordance with the following Boeing service bulletins, which contain the specified effective pages:\n\n\nService Bulletin Referenced and Date\n\nPage Number\nRevision Level\nShown on Page\n Date\nShown on Page\n767-78-0047,\t\nRevision 1,\nMarch 26, 1992\n1-33\n1\nMarch 26, 1992\n767-78-0047,\t\nRevision 2,\t\nJanuary 21, 1993\n1-2, 4, 12-13,\n20-32\n\n3, 5, 10-11,\n14-15, 17-19\n\n6-9, 16\n2\n\n\n1\n\n\nOriginal\nJanuary 21, 1993\n\n\nMarch 26, 1992\n\n\nAugust 22, 1991\n767-78-0047, Revision 3,\nJuly 28, 1994\n1-32\n3\nJuly 28, 1994767-78-0063,\t\nRevision 2,\nApril 28, 1994\n1-292\n2\nApril 28, 1994\n\nThis 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, as of August 18, 1995 (60 FR 36976, July 19, 1995). 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.\n\n\t(i)\tThis amendment is effective on August 18, 1995.\n\nAPPENDIX 1\n\nTHRUST REVERSER ELECTRO-MECHANICAL BRAKE AND CDU CONE BRAKE TEST\n\n1.\tGeneral\n\tA.\tThis procedure contains steps to do two checks:\n\t\t(1)\tA check of the holding torque of the electro-mechanical brake.\n\t\t(2)\tA check of the holding torque of the CDU cone brake.\n\n2.\tElectro-Mechanical Brake and CDU Cone Brake Torque Check (Fig. 1)\n\tA.\tPrepare to do the checks:\n\t\t(1)\tOpen the fan cowl panels.\n\tB.\tDo a check of the torque of the electro-mechanical brake:\n\t\t(1)\tDo a check of the running torque of the thrust reverser system:\n\t\t\t(a)\tManually extend the thrust reverser six inches and measure the running \t\t\t\t\ttorque.\n\t\t\t\t1)\tMake sure the torque is less than 10 pound-inches.\n\n\t\t(2)\tDo a check of the electro-mechanical brake holding torque:\n\t\t\t(a)\tMake sure the thrust reverser translating cowl is extended at least one inch.\n\t\t\t(b)\tMake sure the CDU lock handle is released.\n\t\t\t(c)\tPull down on the manual release handle on the electro-mechanical brake until the handle fully engages the retaining clip.\n\n\t\t\tNOTE: This will lock the electro-mechanical brake.\n\n\t\t\t(d)\tWith the manual drive lockout cover removed from the CDU, install a 1/4-inch extension tool and dial-type torque wrench into the drive pad.\n\n\t\t\tNOTE: You will need a 24-inch extension to provide adequate clearance for the torque wrench.\n\n\t\t\t(e)\tApply 90 pound-inches of torque to the system.\t\n\n\t\t\t\t1)\tThe electro-mechanical brake system is working correctly if the torque is reached before you turn the wrench 450 degrees (1-1/4 turns).\n\n\t\t\t\t2)\tIf the flexshaft turns more than 450 degrees before you reach the specified torque, you must replace the long flexshaft between the CDU and the upper angle gearbox.\n\n\t\t\t\t3)\tIf you do not get 90 pound-inches of torque, you must replace the electro-mechanical brake.\n\n\t\t\t(f)\tRelease the torque by turning the wrench in the opposite direction until you read zero pound-inches.\n\n\t\t\t\t1)\tIf the wrench does not return to within 30 degrees of initial starting point, you must replace the long flexshaft between the CDU and upper angle gearbox.\n\n\t\t(3)\tFully retract the thrust reverser.\n\n\tC.\tDo a check of the torque of the CDU cone brake:\n\n\t\t(1)\tPull up on the manual release handle to unlock the electro-mechanical brake.\n\t\t(2)\tPull the manual brake release lever on the CDU to release the cone brake.\n\n\t\t\tNOTE: This will release the pre-load tension that may occur during a stow cycle.\n\n\t\t(3)\tReturn the manual brake release lever to the locked position to engage the cone brake.\n\n\t\t(4)\tRemove the two bolts that hold the lockout plate to the CDU and remove the lockout plate.\n\n\t\t(5)\tInstall a 1/4-inch drive and a dial-type torque wrench into the CDU drive pad.\n\n\t\tCAUTION: DO NOT USE MORE THAN 100 POUND-INCHES OF TORQUE WHEN YOU DO THIS CHECK. EXCESSIVE TORQUE WILL DAMAGE THE CDU.\n\n\t\t(6)\tTurn the torque wrench to try to manually extend the translating cowl until you get at least 15 pound-inches.\n\n\t\t\tNOTE: The cone brake prevents movement in the extend direction only. If you try to measure the holding torque in the retract direction, you will get a false reading.\n\n\t\t\t(a)\tIf the torque is less than 15 pound-inches, you must replace the CDU.\n\n\tD.\tReturn the airplane to its usual condition:\n\n\t\t(1)\tFully retract the thrust reverser.\n\t\t(2)\tPull down on the manual release handle on the electro-mechanical brake until the handle fully engages the retaining clip.\n\n\t\t\tNOTE: This will lock the electro-mechanical brake.\n\n\t\t(3)\tClose the fan cowl panels.\n\nElectro-Mechanical Brake and CDU Cone Brake Torque Check\nFigure 1\nAD 95-13-12 R1

On June 22, 1995, the FAA issued AD 95-13-12, amendment 39-9292 (60 FR 36976, July 19, 1995), which is applicable to certain Boeing Model 767 series airplanes. That AD requires tests, inspections, and adjustments of the thrust reverser system. That AD also requires installation of a terminating modification and repetitive follow-on actions. That action was prompted by the identification of a modification that ensures that the level of safety inherent in the original type design of the thrust reverser system is further enhanced. The actions required by that AD are intended to prevent possible discrepancies that exist in the current thrust reverser control system, which could result in inadvertent deployment of a thrust reverser during flight.\n\n\tSince the issuance of that AD, the manufacturer has advised the FAA that a torque check value specified in Appendix 1 of the AD requires clarification. The procedures originally provided to the FAA for accomplishment of a torque check of the cone brake of the center drive unit (CDU) indicate that operators should not use more than 130 pound-inches of torque when performing the check. While using 130 pound-inches of torque would not damage the CDU, the manufacturer has advised the FAA that 100 pound-inches of torque is the appropriate value. Accomplishing the torque check up to 100 pound-inches is intended to identify a CDU having a decaying torque level due to a soft shaft problem, while at the same time not exposing the brake to unnecessarily high torque/stress levels.\n\n\tAction is taken herein to clarify this requirement of AD 95-13-12 and to correctly add the AD as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13).\n\n\tThe final rule is being reprinted in its entirety for the convenience of affected operators. The effective date remains August 18, 1995.\n\n\tSince this action only clarifies a current requirement, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary.\n\nList of Subjects in 14 CFR Part 39\n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Correction\n\n\tAccordingly, 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:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701.§ 39.13 - (Amended)\n\n\t2. Section 39.13 is amended by removing amendment 39-9292 (60 FR 36976, July 19, 1995), and by adding a new airworthiness directive (AD), amendment 39-9528, to read as follows: