[Federal Register Volume 59, Number 22 (Wednesday, February 2, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-2334] [[Page Unknown]] [Federal Register: February 2, 1994] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 93-NM-178-AD] Airworthiness Directives; Boeing Model 767 Series Airplanes Equipped With Pratt and Whitney JT9D-7R4 or General Electric CF6-80A Series Engines AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 767 series airplanes, that currently requires inspections, adjustments, and functional checks of the thrust reverser system. This action would add a requirement for installation of an additional thrust reverser system locking feature, periodic functional tests of that locking feature following its installation, and repair of any discrepancy found. This proposal 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 the proposed AD are intended to prevent possible discrepancies in the thrust reverser control system that can result in the inadvertent deployment of a thrust reverser during flight. DATES: Comments must be received by March 29, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-178-AD, 1601 Lind Avenue SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 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: Richard Simonson, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 98055-4056; telephone (206) 227-2683; fax (206) 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 filed in 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 93-NM-178-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-103, Attention: Rules Docket No. 93-NM-178-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion On January 7, 1992, the FAA issued AD 92-03-03, Amendment 39-8157 (57 FR 3004, January 27, 1992), applicable to certain Boeing Model 767 series airplanes, to require inspections, adjustments, and functional checks of the thrust reverser system. That action was prompted by an ongoing design review, resulting from an accident investigation from which it has been determined that, prior to the accident, the airplane apparently experienced an uncommanded in-flight deployment of a thrust reverser. Deployment of a thrust reverser during flight could result in reduced controllability of the airplane. The requirements of that AD are intended to ensure the integrity of the fail safe features of the thrust reverser system by preventing the possible discrepancies in the thrust reverser control system that can result in the inadvertent deployment of a thrust reverser during flight. Since the issuance of that AD, Boeing has developed a modification for Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 or General Electric CF6-80A series engines, which, when accomplished, will ensure that the level of safety inherent in the original type design of the thrust reverser system is further enhanced. The FAA has determined that the installation of these additional features will further reduce the likelihood of an in-flight thrust reverser deployment. The FAA has reviewed and approved Boeing Service Bulletin 767-78- 0060, Revision 2, dated August 19, 1993 (for Model 767 series airplanes equipped with General Electric CF6-80A series engines), and Boeing Service Bulletin 767-78-0061, Revision 1, dated August 5, 1993 (for Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines). These service bulletins describe procedures for installation of an additional thrust reverser system locking feature (denoted as a ``synch-lock''), which will reduce the possibility of an uncommanded in-flight deployment of the thrust reversers. Accomplishment of that installation includes revising certain wiring, replacing selected circuit breakers, changing the microswitch pack, and adding electrical components. The synch-lock is controlled independently of the existing electro-mechanical safety features of the thrust reverser system. This additional locking feature has been certified by the FAA. The FAA has determined that installation of the synch-lock in accordance with the applicable service bulletin is necessary in order to positively address the identified unsafe condition with regard to these airplanes. 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 supersede AD 92-03-03 to continue to require repetitive inspections, adjustments, and functional checks of the thrust reverser system. This action would add a requirement for installation of an additional thrust reverser system locking feature (synch-lock). Installation of the synch-lock would terminate the requirement for repetitive inspections, adjustments, and functional checks of the thrust reverser system. The synch-lock installation would be required to be accomplished in accordance with the service bulletin described previously. This AD would also add periodic functional tests of the synch-lock following its installation, and repair of any discrepancy found. The FAA has determined that these tests are necessary to ensure the integrity of the synch-lock installation and that it is effective in preventing the identified unsafe condition. This determination is based on the fact that the synch-lock is a new design and its reliability has not been adequately proven through service experience. Boeing has submitted to the FAA procedures for accomplishment of the synch-lock integrity test described in the airplane maintenance manual. These procedures are accomplished independently of other thrust reverser system tests. Since only limited information is available currently to substantiate the in-service reliability of the synch-lock device, the FAA has established an appropriate functional test interval of 1,000 hours time-in-service. There are approximately 119 Model 767 series airplanes equipped with General Electric CF6-80A series engines of the affected design in the worldwide fleet. The FAA estimates that 69 of these airplanes of U.S. registry would be affected by this proposed AD. The inspections, adjustments, and functional checks required currently by AD 92-03-03 require approximately 16 work hours per airplane to accomplish, at an average labor rate of $55 per work hour. Based on these figures, the total cost impact of that action on U.S. operators of Model 767 series airplanes equipped with General Electric CF6-80A series engines is estimated to be $60,720, or $880 per airplane. For U.S. operators of Model 767 series airplanes equipped with General Electric CF6-80A series engines, the FAA estimates that it would take approximately 786 work hours per airplane to accomplish the modification proposed by this AD, and 1 work hour to accomplish the proposed functional tests, at an average labor rate of $55 per work hour. Required parts would be supplied by the manufacturer at no cost to operators. Based on these figures, the total cost impact of the proposed AD on U.S. operators of Model 767 series airplanes equipped with General Electric CF6-80A series engines is estimated to be $2,986,665, or $43,285 per airplane. There are approximately 95 Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines of the affected design in the worldwide fleet. The FAA estimates that 30 of these airplanes of U.S. registry would be affected by this proposed AD. The inspections, adjustments, and functional checks required currently by AD 92-03-03 require approximately 16 work hours per airplane to accomplish, at an average labor rate of $55 per work hour. Based on these figures, the total cost impact of that action on U.S. operators of Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines is estimated to be $26,400, or $880 per airplane. For U.S. operators of Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines, the FAA estimates that it would take approximately 812 work hours per airplane to accomplish the proposed modification, and 1 work hour to accomplish the proposed functional tests, at an average labor rate of $55 per work hour. Required parts would be supplied by the manufacturer at no cost to operators. Based on these figures, the total cost impact of the proposed AD on U.S. operators of Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines is estimated to be $1,341,450, or $44,715 per airplane. These total cost figures assume that no operator has yet accomplished the proposed requirements of this AD action. The number of required work hours for accomplishing the proposed functional tests, as indicated above, is presented as if the accomplishment of those tests proposed in this AD were to be conducted as ``stand alone'' actions. However, in actual practice, those tests for the most part would be accomplished coincidentally or in combination with normally scheduled airplane inspections and other maintenance program tasks. Therefore, the actual number of necessary additional work hours for accomplishment of the functional tests would be minimal in many instances. Additionally, any costs associated with special airplane scheduling would be minimal. The FAA recognizes that the proposed modification would require a large number of work hours to accomplish. However, the 5-year compliance time specified in paragraph (d) of this proposed AD should allow ample time for the synch-lock installation to be accomplished coincidentally with scheduled major airplane inspection and maintenance activities, thereby minimizing the costs associated with special airplane scheduling. 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 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The 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. Sec. 39.13 [Amended] 2. Section 39.13 is amended by removing amendment 39-8157 (57 FR 3004, January 27, 1992), and by adding a new airworthiness directive (AD), to read as follows: Boeing: Docket 93-NM-178-AD. Supersedes AD 92-03-03, Amendment 39- 8157. Applicability: Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 or General Electric CF6-80A series engines; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To ensure the integrity of the fail safe features of the thrust reverser system, accomplish the following: Restatement of Actions Required by AD 92-03-03: (a) For airplanes equipped with Pratt and Whitney JT9D-7R4 series engines: Within 60 days after the effective date of this AD, and thereafter at intervals not to exceed 3,000 flight hours, perform the tests, inspections, and adjustments described in Boeing Service Bulletin 767-78-0054, dated December 13, 1991. (1) Following any maintenance action that could affect the thrust reverser system: Repeat the tests, inspections, and adjustments required by paragraph (a) of this AD on the affected engine, prior to further flight, in accordance with the service bulletin. (2) Thereafter, following any maintenance action, continue to perform the repetitive tests, inspections, and adjustments required by paragraph (a) of this AD on the affected engine at intervals not to exceed 3,000 flight hours. (b) For airplanes equipped with General Electric CF6-80A series engines: Within 60 days after the effective date of this AD, and thereafter at intervals not to exceed 3,000 flight hours, perform the tests, inspections, and adjustments described in Boeing Service Bulletin 767-78-0053, dated December 13, 1991. (1) Following any maintenance action that could affect the thrust reverser system, repeat the tests, inspections, and adjustments required by paragraph (b) of this AD on the affected engine, prior to further flight, in accordance with the service bulletin. (2) Thereafter, following any maintenance action, continue to perform the repetitive tests, inspections, and adjustments required by paragraph (b) of this AD on the affected engine at intervals not to exceed 3,000 flight hours. (c) If any test, inspection, and/or adjustment required by paragraph (a) or (b) of this AD cannot be successfully performed, or if any test, inspection, and/or adjustment results in findings that are unacceptable in accordance with Boeing Service Bulletin 767-78- 0054, dated December 13, 1991, or Boeing Service Bulletin 767-78- 0053, dated December 13, 1991, as applicable, accomplish paragraphs (c)(1) and (c)(2) of this AD. (1) 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. No more than one thrust reverser on any airplane may be deactivated under the provisions of this paragraph. (2) Within 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 767-78-0054, dated December 13, 1991, or Boeing Service Bulletin 767-78-0053, dated December 13, 1991, as applicable; the tests and/or inspections required by paragraph (a) or (b) of this AD must be successfully accomplished; and the thrust reverser must then be reactivated. New Actions Required by This AD: (d) Within 5 years after the effective date of this AD, install an additional thrust reverser system locking feature (synch-lock installation) in accordance with Boeing Service Bulletin 767-78- 0060, Revision 2, dated August 19, 1993 (for Model 767 series airplanes equipped with General Electric CF6-80A series engines), or Boeing Service Bulletin 767-78-0061, Revision 2, dated August 5, 1993 (for Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4 series engines), as applicable. Installation of the additional thrust reverser system locking feature, as required by this paragraph, constitutes terminating action for the requirements of paragraphs (a) through (c) of this AD. (e) Within 1,000 hours time-in-service after installing the synch-lock required by paragraph (d) of this AD (either in production or by retrofit), or within 1,000 hours time-in-service after the effective date of this AD, whichever occurs later; and thereafter at intervals not to exceed 1,000 hours time-in-service: Perform functional tests of the synch-lock in accordance with the ``Thrust Reverser Synch-Lock Test'' procedures specified below. If any discrepancy is found during any test, prior to further flight, correct it in accordance with procedures described in the Boeing 767 Maintenance Manual. Thrust Reverser Synch-Lock Test 1. General A. There are two thrust reverser synch-locks on each engine. The thrust reverser synch-locks are installed on the lower non-locking hydraulic actuator of each thrust reverser sleeve. B. This task has two parts that must be accomplished: (1) The first part does a test of the electrical circuit which controls the operation of each thrust reverser synch-lock. (2) The second part does a test of the mechanical condition of each thrust reverser synch-lock. C. The thrust reverser synch-lock is referred to as the ``synch- lock'' in this procedure. 2. Thrust Reverser Synch-Lock Integrity Test A. Equipment (1) Multi-meter, Simpson 260 or equivalent--commercially available. B. Prepare to do the integrity test for the synch-locks. (1) Supply electrical power. (2) For the left engine, make sure these circuit breakers on the overhead circuit breaker panel, P11, are closed: (a) L ENG T/R CONT (b) L ENG T/R IND (c) L ENG T/R SSL CONT (3) For the right engine, make sure these circuit breakers on the overhead circuit breaker panel, P11, are closed: (a) R ENG T/R CONT (b) R ENG T/R IND (c) R ENG T/R SSL CONT (d) AIRPLANES WITH HYDRAULIC MOTOR-DRIVEN GENERATORS (ETOPS): R ENG T/R CONT ALTN (e) AIRPLANES WITH HYDRAULIC MOTOR-DRIVEN GENERATORS (ETOPS): R ENG T/R IND ALTN (4) Open the fan cowl panels. C. Do the electrical test for the synch-locks. (1) Do these steps to make sure there are no ``hot'' short circuits in the electrical system which can accidentally supply power to the synch-locks: (a) Remove the applicable L(R) electrical connectors, D20194(D20196), from the L(R) synch-locks, V170(V171). Note: You can find the synch-locks attached to the lower non- locking hydraulic actuators on the applicable thrust reverser sleeves. (b) Use a multi-meter on the plug end of the applicable electrical connector to make sure that these conditions are correct: ------------------------------------------------------------------------ From equipment To equipment Condition ------------------------------------------------------------------------ D20194 PIN 1........... D20194 PIN 2........... -3 to +1 VDC and continuity (less than 5 ohms). D20196 PIN 1........... D20196 PIN 2........... -3 to +1 VDC and continuity (less than 5 ohms). ------------------------------------------------------------------------ (c) If you did not find these conditions to be correct, you must do these steps: (1) Make a careful visual inspection of all the electrical wires and connectors between the synch-lock and its applicable power circuit breaker. (2) Repair all the unserviceable electrical wire and connectors that you find. (3) Use the multi-meter again to make sure there are no ``hot'' short circuits in the electrical system which can accidentally supply power to the synch-locks. (d) If you find the correct conditions when you use the multi- meter, continue on and do the mechanical test of the synch-locks. Note: Make sure the circuit breakers shown above continue to be set to the closed position. Do not install the electrical connectors on the synch-locks at this time. D. Do the mechanical test for the synch-locks. (1) Supply hydraulic power. 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 synch-locks do not operate correctly and the thrust reverser extends. (2) Move the reverse thrust levers for the two engines to try to extend the thrust reversers with hydraulic power. Note: If the thrust reversers do not extend, the synch-locks are serviceable. If the thrust reversers extend, the applicable synch- locks did not operate correctly. (3) Replace the applicable synch-locks on the thrust reverser that extended when you moved the reverse thrust levers. (4) Make sure the reverse thrust levers are in the fully stowed position. (5) Install the applicable L(R) electrical connectors, D20194(D20196), on the L(R) synch-locks, V170(V171). 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. (6) Move the reverser thrust levers for the two engines to extend the thrust reversers with hydraulic power. Note: If the thrust reversers extend, the synch-locks are serviceable. If the thrust reversers do not extend, the applicable synch-locks did not operate correctly. (7) Replace the applicable synch-locks on the thrust reverser that did not extend when you moved the reverse thrust levers. E. Put the airplane back to its usual condition. (1) Move the reverse thrust levers to fully retract the thrust reversers on the two engines with hydraulic power. (2) Remove the hydraulic power if it is not necessary. (3) Remove the electrical power if it is not necessary. (4) Close the fan cowl panels. (f) 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: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (g) Special flight permits may be issued in accordance with FAR 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 January 27, 1994. James V. Devany, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-2334 Filed 2-1-94; 8:45 am] BILLING CODE 4910-13-P