AD 94-12-10

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires repetitive inspections, tests, adjustments, and functional checks of the thrust reverser system and of selected engine wiring. This amendment adds a requirement for installation of a terminating modification, repetitive operational checks of that installation, and repair of any discrepancy found. This amendment is 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 specified by this AD are intended to prevent deployment of a thrust reverser in flight and subsequent reduced controllability of the airplane.

Final rule

94-12-10 BOEING: Amendment 39-8938. Docket 93-NM-142-AD. Supersedes AD 92-24-03, Amendment 39-8408. \n\n\tApplicability: Model 767 series airplanes equipped with Pratt & Whitney PW4000 series engines; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tNOTE 1: Paragraphs (a) and (b) of this AD restate the requirements of AD 92-24-03, amendment 39-8408, paragraphs (a) and (b). As allowed by the phrase, "unless accomplished previously," if the requirements of AD 92-24-03 have been accomplished previously, paragraphs (a) and (b) of this AD do not require that they be repeated. \n\n\tNOTE 2: Paragraph (c)(1) of this AD restates the requirement for an initial and repetitive inspections, tests, adjustments, and functional checks contained in paragraph (c)(1) of AD 92-24-03. Therefore, for operators who have previously accomplished at least the initial inspection in accordance with AD 92-24-03, paragraph (c)(1) of this AD requires that the next scheduled inspection be performed within 3,000 flight hours after the last inspection performed in accordance with paragraph (c)(1) of AD 92-24-03. \n\n\tNOTE 3: Paragraph (c)(2) of this AD restates the requirement for an initial and repetitive checks of the grounding wire contained in paragraph (c)(2) of AD 92-24-03. Therefore, for operators who have previously accomplished at least the initial inspection in accordance with AD 92-24-03, paragraph (c)(2) of this AD requires that the next scheduled inspection be performed within 1,500 flight hours after the last inspection performed in accordance with paragraph (c)(2) of AD 92-24-03. \n\n\tTo ensure the integrity of the fail safe features of the thrust reverser system, accomplish the following: \n\n\t(a)\tWithin 7 days after August 23, 1991 (the effective date of AD 91-18-51, amendment 39-8069), accomplish the following: \n\n\t\t(1)\tDeactivate both left and right thrust reversers in accordance with Section 78-31-1 of BoeingDocument D630T002, "Boeing 767 Dispatch Deviation Guide," Revision 9, dated May 1, 1991. \n\n\t\t(2)\tAdd the following to the Limitations Section of the FAA-approved Airplane Flight Manual (AFM). This may be accomplished by placing a copy of this AD in the AFM. "Reduce by five percent the available accelerate-stop distance resulting from the Airplane Flight Manual takeoff performance analysis when the runway is wet or contaminated." \n\n\t(b)\tWithin 60 days after November 8, 1991 (the effective date of AD 91-22-09, amendment 39-8069), modify the thrust reverser system in accordance with Boeing Service Bulletin 767-78-0051, dated October 9, 1991. Once this modification is accomplished, the thrust reverser system shall be re-activated and the AFM limitation required by paragraph (a)(2) of this AD may be removed. \n\n\t(c)\tAccomplish the actions specified in paragraphs (c)(1) and (c)(2) of this AD at the times specified in those paragraphs. \n\n\t\t(1)\tPrior to the accumulation of 3,000 flight hours since manufacture, or within 30 days after November 24, 1992 (the effective date of AD 92-24-03, amendment 39-8408), whichever occurs later, perform all inspections, tests, adjustments, and functional checks of the thrust reverser control and indication system and engine wiring specified in Boeing Service Bulletin 767-78-0046, Revision 1, dated September 17, 1992, in accordance with the procedures described in that service bulletin. \n\n\t\t\t(i)\tRepeat those actions thereafter at intervals not to exceed 3,000 flight hours. \n\n\t\t\t(ii)\tWhenever maintenance action is taken that could disturb any portion of the thrust reverser control system, the functional test or tests relative to the system shall be performed in accordance with the Boeing 767 Maintenance Manual. After this test(s) is accomplished, the repetitive inspections, tests, adjustments and functional tests required by paragraph (c)(1)(i) of this AD shall continue. \n\n\t\t(2)\tPrior to the accumulation of 1,500 flight hours since manufacture, or within 30 days after November 24, 1992 (the effective date of AD 92-24-03, amendment 39-8408), whichever occurs later, perform a check of the grounding wire for the thrust reverser directional control valve (DCV) in accordance with Section III, paragraph B., of Boeing Service Bulletin 767- 78-0046, Revision 1, dated September 17, 1992. Thereafter, repeat this check at the times specified in paragraph (c)(2)(i) and (c)(2)(ii) of this AD. \n\n\t\t\t(i)\tAt intervals not to exceed 1,500 flight hours; and \n\t\t\t(ii)\tWhenever maintenance action is taken that could disturb the \t\t\t\tDCV grounding circuit. \n\n\t(d)\tIf any of the inspections, tests, adjustments, and/or functional checks required by paragraph (c) of this AD cannot be performed successfully as specified in the service bulletin, prior 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. The thrust reverser shall remain deactivated until all inspections, tests, adjustments, and functional tests required by paragraph (c) of this AD are completed successfully.\n \n\t(e)\tWithin 3 years after the effective date of this AD, install an additional thrust reverser system locking feature (sync-lock) in accordance with Boeing Service Bulletin 767-78-0062, Revision 2, dated June 3, 1993, or Revision 3, dated February 24, 1994. Installation of this additional locking feature constitutes terminating action for the requirements of paragraph (c) of this AD. \n\n\t(f)\tWithin 4,000 hours time-in-service after accomplishing the modification required by paragraph (e) of this AD, or within 4,000 hours time-in-service after the effective date of this AD, whichever occurs later; and thereafter at intervals not to exceed 4,000 hours time-in-service: Perform the integrity test of the thrust reverser synchronous shaft locks specified below to detect latent failures of the components and to ensure the integrity of the thrust reverser system. Prior to further flight, repair any discrepancy found in accordance with procedures described in the Boeing 767 Maintenance Manual. \n\n\t\tTHRUST REVERSER SYNC-LOCK - ADJUSTMENT/TEST \n1.\tGeneral \n\n\tA.\tThere are two sync-locks for each engine thrust reverser. The sync-lock is installed on the lower non-locking hydraulic actuator of each thrust reverser sleeve. \n\tB.\tThe Thrust Reverser Sync-Lock Integrity Test has two tasks: \n\t\t(1)\tThe first task tests the electrical circuit which controls the operation of the sync-lock on each thrust reverser sleeve. \n\t\t(2)\tThe second task tests the mechanical function of the sync-lock on each thrust reverser sleeve. \n\tC.\tThe thrust reverser sync-lock is referred to as the sync-lock in this procedure. \n\n2.\tThrust Reverser Sync-Lock Integrity Test \n\n\tA.\tEquipment \n\t\t(1)\tMulti-meter, Simpson 260 or equivalent - commercially available. \n\tB.\tPrepare to do the Integrity Test for the sync-locks. \n\t\t(1)\tSupply electrical power. \n\t\t(2)\tFor the left engine, make sure these circuit breakers on the overhead \t\t\tcircuit breaker panel, P11, are closed: \n\t\t\t(a)\tL ENG T/R CONT \n\t\t\t(b)\tL ENG T/R IND \n\t\t\t(c)\tL ENG T/R SSL CONT \n\t\t(3)\tFor the right engine, make sure these circuit breakers on the overhead \t\t\tcircuit breaker panel, P11, are closed: \n\t\t\t(a)\tR ENG T/R CONT \n\t\t\t(b)\tR ENG T/R IND \n\t\t\t(c)\tR ENG T/R SSL CONT \n\t\t\t(d)\tFOR ETOPS AIRPLANES, CLOSE THESE ADDITIONAL \n\t\t\t\tCIRCUIT BREAKERS: \n\t\t\t\t1)\tR ENG T/R CONT ALTN \n\t\t\t\t2)\tR ENG T/R IND ALTN \n\t\t(4)\tOpen the fan cowl panels. \n\t\n\tC.\tDo the Electrical Integrity Test for the sync-locks. \n\t\t(1)\tDo these steps to make sure there are no "hot" short circuits in the electrical system that may accidentally supply power to the sync-locks: \n\t\t\t(a)\tRemove the electrical connector, D20194, from the sync-locks, V170, on the left sleeve of the thrust reverser. \n\t\t\t(b)\tRemove the electrical connector, D20196, from the sync-lock, V171, on the right sleeve of the thrust reverser. \n\t\t\t(c)\tUse a multi-meter on the plug end of the applicable electrical connector to make sure that these conditions are correct: \n\nFROM EQUIPMENT\t\tTO EQUIPMENT\t\tCONDITION \nD20194, PIN 1\t\t\tD20194, PIN 2\t\t\t-3 TO +1 V DC AND \n\t\t\t\t\t\t\t\tCONTINUITY (LESS \n\t\t\t\t\t\t\t\tTHAN 5 OHMS) \n\nD20196, PIN 1\t\t\tD20196, PIN 2\t\t\t-3 TO +1 V DC AND \n\t\t\t\t\t\t\t\tCONTINUITY (LESS \n\t\t\t\t\t\t\t\tTHAN 5 OHMS) \n\n\t\t\t(d)\tIf you did not find these conditions to be correct, you must do \n\t\t\t\tthese steps: \n\n\t\t\t\t1)\tMake a careful visual inspection of all the electrical \t\t\t\t\twires and connectors between the sync-lock and its power circuit breaker. \n\t\t\t\t2)\tRepair all the unserviceable electrical wire and connectors that you find. \n\t\t\t\t3)\tUse the multi-meter again to make sure there are no \t\t\t\t\t"hot" short circuits in the electrical system that can accidentally supply power to the sync-locks. \n\n\t\t\t(e)\tIf you find the correct conditions, do the Mechanical Integrity \t\t\t\tTest for the sync-locks. \n\tD.\tDo the Mechanical Integrity Test for the sync-locks. \n\t\t(1)\tSupply hydraulic power.\n\n WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE CLEAR OF THE AREA BEHIND EACH THRUST REVERSER. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR IF THE SYNC-LOCKS DO NOT OPERATE CORRECTLY AND THE THRUST REVERSER EXTENDS. \n\t\t(2)\tMove the L(R) reverser thrust lever aft to try to extend the thrust \t\t\t\treverser. \n\nNOTE: If the thrust reverser sleeves do not extend, the sync-locks are serviceable. If the thrust reverser sleeve extends, the applicable sync-lock did not operate correctly. \n\n\t\t(3)\tReplace the sync-lock(s) for the thrust reverser sleeve(s) that \t\t\t\textended. \n\t\t(4)\tMake sure the reverse thrust levers are in the fully stowed position. \n\t\t(5)\tInstall the electrical connectors, D20194, on the sync-locks, V170, on the left sleeve of the thrust reverser. \n\t\t(6)\tInstall the electrical connector, D20196, onthe sync-lock, V171, on the right sleeve of the thrust reverser.\n\n WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE CLEAR OF THE AREA BEHIND THE THRUST REVERSERS. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR WHEN THE THRUST REVERSERS ARE EXTENDED. \n\n\t\t(7)\tMove the L(R) reverser thrust lever aft to extend the thrust reverser. \n\nNOTE: If the thrust reverser sleeves extend, the sync-locks are serviceable. If the thrust reverser sleeve did not extend, the applicable sync-lock did not operate correctly. \n\n\t\t(8)\tReplace the sync-lock(s) on the thrust reverser sleeve(s) that did not extend when you moved the reverse thrust levers. \n\tE.\tRepeat the Thrust Reverser Sync-Lock Integrity Test for the opposite engine. \n\tF.\tPut the airplane back to its usual condition. \n\t\t(1)\tMove the reverser thrust levers to fully retract the thrust reversers on the two engines with hydraulic power. \n\t\t(2)\tRemove the hydraulic power if it is not necessary. \n\t\t(3)\tRemove the electrical power if it is not necessary. \n\t\t(4)\tClose the fan cowl panels. \n\n\tG.\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 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.\n \n\tH.\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\tI.\tThe installation shall be done in accordance with Boeing Service Bulletin 767-78- 0062, Revision 2, dated June 3, 1993; or Boeing Service Bulletin 767-78-0062, Revision 3, dated February 24, 1994. The incorporation by reference of these documents was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. The inspections, tests, adjustments, and functional checks shall be done in accordance with Boeing Service Bulletin 767-78-0046, Revision 1, dated September 17, 1992. The incorporation by reference of this document was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 as of November 24, 1992 (57 FR 53258, November 9, 1992). The modification and deactivation shall be done in accordance with Boeing Service Bulletin 767-78-0051, dated October 9, 1991; and Boeing Document D630T002, "Boeing 767 Dispatch Deviation Guide," Revision 9, dated May 1, 1991. The incorporation by reference of these documents was approved previously by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51 as of November 8, 1991 (56 FR 55066, October 24, 1991). 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\tJ.\tThis amendment becomes effective on July 20, 1994.

A proposal to amend part 39 of the Federal Aviation Regulations by superseding AD 92-24-03, amendment 39-8408 (57 FR 53258, November 9, 1992), which is applicable to certain Boeing Model 767 series airplanes, was published in the Federal Register on October 7, 1993 (58 FR 52243). The action proposed to continue to require repetitive inspections, tests, adjustments, and functional checks of the thrust reverser system and of selected engine wiring; and to add a requirement for installation of a terminating modification, repetitive operational checks of that installation, and repair of any discrepancy found. \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.\n \n\tOne commenter supports the proposed rule. \n\n\tTwo commenters request that specific references to page numbers and revision dates of the Boeing 767 Airplane Maintenance Manual (AMM), which are specified in paragraph (f) of the proposal, be removed from the proposed rule. Boeing recommends that the proposed AD specify only the ATA Chapter-Section-Subject, pageblock title, and task title. Boeing explains that the AMM's are customized for each operator to reflect all of the equipment in that operator's fleet. Therefore, the number of pages for any given procedure is variable, depending on the number of different equipment configurations documented in an operator's AMM. Boeing also indicates that AMM procedures are revised periodically for non-technical reasons. Boeing adds that changes to the structure of the procedures are necessary to accommodate an upgrade of the publishing system that is currently under way, which, in addition to repagination, will necessitate the issuance of revised AMM pages. \n\n\tBoeing also requests that a reference to a specific Temporary Revision (TR) number, which is specified in "NOTE 4" under paragraph (c) of the proposal, be eliminatedfrom the proposed rule. Boeing explains that because of the customization of AMM's for each operator, multiple TR's may be issued to address a technical concern. While changes to the procedure can be identical for all operators, the page layout of each operator's AMM can require a unique TR to allow the operator to correctly integrate the TR into the AMM. Since each unique TR has a different number, the specific TR referenced in the proposal only applies to the AMM's for three operators of a possible 18 operators. Additionally, TR's are removed from an operator's AMM and destroyed when the data is incorporated in a subsequent regular revision. The procedural changes in the TR cited in the proposal were incorporated into the AMM in November 1992, and instructions were provided in an AMM transmittal letter to remove the TR. Therefore, it is probable that operators no longer have the TR that was cited in the proposed rule. \n\n\tBoeing concludes that the net effect of specifying AMMpage numbers, AMM revision dates, and TR's in the AD would be that operators may be unable to use the procedure contained in the AMM to perform certain tests required by the AD. Each operator would be required to maintain an obsolete version of the procedure, or to request FAA approval of an alternative method of compliance with the AD that would allow the use of the current version of the AMM. \n\n\tThe FAA concurs partially. In light of the information submitted by the commenters, the FAA finds that specific reference to the TR cited in "NOTE 4" under paragraph (c) of the proposal should not be specified in the final rule. Accordingly, "NOTE 4" has been removed from the final rule. Additionally, the FAA's objective in proposing periodic operational checks of the sync-lock device, as specified in paragraph (f) of this AD, is to ensure the integrity of the locking function. However, since the issuance of the proposal and receipt of Boeing's comments to the proposal, Boeing has submitted to the FAA separate procedures for accomplishment of the operational checks of the sync-lock integrity. Therefore, these procedures have been defined in paragraph (f) of the final rule, and the AMM references specified previously in paragraph (f) of the proposal have been removed from the final rule. \n\n\tThe Air Transport Association (ATA) of America, on behalf of its members, states that, while ATA members are not opposed to accomplishing the proposed checks as part of their maintenance programs, these members are opposed to accomplishing the checks as part of the requirements of an AD. The commenters believe that the requirement for operational checks is equivalent to issuing a Certification Maintenance Requirements (CMR) item by means of an AD. \n\n\tATA adds that, if the FAA finds sufficient justification to include the requirement for operational checks in the AD, an alternative to accomplishment of the checks should be provided in the final rule. ATA reasons that an alternative is justified because no data exist to show that repetitive checks of a modified thrust reverser cannot be handled adequately through an operator's maintenance program. The suggested alternative follows: Within 3 months after accomplishing the sync-lock installation, revise the FAA-approved maintenance inspection program to include an operational check of the sync-lock. The initial check would be accomplished within 1,000 hours time-in-service after modification. The AD would no longer be applicable for operators that have acceptably revised the maintenance program. Operators choosing this alternative could use an alternative recordkeeping method in lieu of that required by Federal Aviation Regulation (FAR) 91.417 or 121.380. The FAA would be defined as the cognizant Principal Maintenance Inspector (PMI) for operators electing this alternative. \n\n\tThe FAA recognizes the concerns of the commenter regarding the requirement for periodic operational checks of the sync-lock following its installation. However, the FAA finds that the operational checks are necessary in order to provide an adequate level of safety and to ensure the integrity of the sync-lock installation. The actions required by this AD are consistent with actions that have been identified by an industry-wide task force as necessary to ensure adequate safety of certain thrust reverser systems installed on transport category airplanes. Representatives of the Aerospace Industries Association (AIA) of America, Inc., and the FAA comprise that task force. Representatives from other organizations, such as ATA, have participated in various discussions and work activities resulting from the recommendations of the task force. \n\n\tThe FAA acknowledges that the operational checks specified in this AD and CMR items are similar in terms of scheduled maintenance and recordkeeping. This AD addresses an unsafe condition and requires installation of the sync-lock to correct that unsafe condition. The FAA has determined that the requirement for operational checks is necessary in order to ensure the effectiveness of that installation in addressing the unsafe condition. This determination is based on the fact that the sync-lock is a new design whose reliability has not been adequately proven through service experience. In addition, service experience to date has demonstrated that failures can occur within the sync-lock that may not be evident during normal operation of the thrust reverser system and may not result in activation of the sync-lock "unlock" indicator. The ATA's suggested alternative to accomplishment of the operational checks would permit each operator to determine whether and how often these checks should be conducted. In light of the severity of the unsafe condition, however, the FAA has determined that allowing this degree of operator discretion is not appropriate at this time. Therefore, this AD is necessary to ensure that operators accomplish checks of the integrity of the sync-lock installation in a common manner and at common intervals. \n\n\tThe FAA also finds that addressing operational checks of the sync-lock integrity in a recommended action, such as an MRB report, will not ensure an acceptable level of safety with regard to the thrust reverser system. However, the FAA recognizes that an operational check interval of 4,000 hours time-in-service, which will be recommended by Boeing for inclusion in the next revision to the MRB report, corresponds more closely to the interval at which most of the affected operators conduct regularly scheduled "C" checks. The FAA has reconsidered the proposed interval of 1,000 hours time-in-service for accomplishment of repetitive operational checks. In light of the safety implications of the unsafe condition addressed and the practical aspects of accomplishing orderly operational checks of the fleet during regularly scheduled maintenance where special equipment and trained maintenance personnel will be readily available, the FAA finds that accomplishment of the checks at intervals of 4,000 hours time-in- service will provide an acceptable level of safety. Paragraph (f) of the final rule has been revised accordingly. \n\n\tSince issuance of the notice, the FAA has reviewed and approved Boeing Service Bulletin 767-78-0062, Revision 3, dated February 24, 1994. This revised service bulletin is essentially identical to the previous revision (which was cited in the notice), but contains certain minor editorial changes. The FAA has revised the final rule to include this revised service bulletin as an additional source of appropriate service information. \n\n\tAfter 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 scopeof the AD. \n\n\tThere are approximately 88 Model 767 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 26 airplanes of U.S. registry will be affected by this AD, that it will take approximately 480 work hours per airplane to accomplish the required modification, and 1 work hour to accomplish the required operational checks, at an average labor rate is $55 per work hour. Required parts will be provided by the manufacturer at no cost to operators. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $687,830, or $26,455 per airplane. \n\n\tThe total cost impact figure discussed above is 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. \n\n\tThe 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. \n\n\tFor 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."\n\n List of Subjects in 14 CFR Part 39 \n\nAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment \n\nAccordingly, 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 \n\n1.\tThe authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. § 39.13 - (Amended) \n\n2.\tSection 39.13 is amended by removing amendment 39-8408 (57 FR 53258, November 9, 1992), and by adding a new airworthiness directive (AD), amendment 39-8938, to read as follows: