# AD 79-08-01 R1: Thrust Reversers - Type: Airworthiness directive - Status: Current - Products: Learjet 35, 35A (C-21A), 36 and 36A - Effective: April 19, 1982 - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Large airplane - Amendment: 39-4361 - Registered aircraft: 211 may be affected, by airframe or engine model (OpenAirDocs) - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2684370DC91777428625696E00542D42.0001 - DRS record last changed: May 30, 2024 - Page: https://openairdocs.org/ad/79-08-01-R1 ## The airworthiness directive 79-08-01 R1 GATES LEAR JET: Amendment 39-3447 as amended by Amendment 39- 4361. Applies to Models 35, 35A, 36 and 36A airplanes equipped with Aeronca thrust reversers. COMPLIANCE: Required as indicated unless already accomplished. To preclude inadvertent thrust reverser deployment and possible loss of aircraft control, prior to next flight accomplish the following: A) Insert in the Aeronca Thrust Reverser Supplement to the Airplane Flight Manual the FAA-approved temporary changes shown herein as Figures I, II and III or the FAA-approved Flight Manual Supplement changes (temporary or permanent) supplied by the manufacturer and containing the same information as the above figures. B) Operate the airplane in accordance with instructions in the Flight Manual Supplement changes specified in Paragraph A) of this Airworthiness Directive. C) Airplanes may make one flight to the location where the changes to the Aeronca Thrust Reverser Supplement to the Airplane Flight Manual specified in this Airworthiness Directive are available, providing the Exterior Inspection in Figure II and Limitations in Figure I are complied with. D) The installation of Gates Learjet Thrust Reverser Blocker Door Position Indication System, per Gates Learjet Corporation Modification Kit No. AMK 81-6, constitutes terminating action for the requirements of paragraphs A), B), and C) of this AD. E) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. Amendment 39-3447 became effective on April 19, 1979, to all persons except those to whom it had already been made effective by an airmail letter from the FAA dated March 1, 1979. This Amendment 39-4361 becomes effective April 19, 1982. FIGURE I TEMPORARY CHANGE, SUPPLEMENT FOR AERONCA THRUST REVERSERS Aircraft Affected: All Gates Lear Jet Model 35, 36, 35A, 36A Aircraft equipped with Aeronca Thrust Reversers. Description of Change: Add Limitations to Section I of the Aeronca Thrust Reverser AFM Supplement. Filing Instructions: Insert this page adjacent to page 2 of 23 in your Thrust Reverser Supplement and retain until further notice. Amend Section I - Limitations by adding the following limitations: Section I - LIMITATIONS (Cont) 7. Thrust Reversers must not be operated prior to takeoff. 8. Thrust Reversers must not be used to control taxi speed, except after landing. 9. Thrust Reversers must not be used for touch and go landings. 10. After Thrust Reversers have been deployed, a visual check of proper door stowing must be made prior to takeoff. 11. Operational Procedures in this Thrust Reverser Supplement are mandatory. FIGURE II TEMPORARY CHANGE, SUPPLEMENT FOR AERONCA THRUST REVERSERS Aircraft Affected: All Gates Lear Jet Model 35, 36, 35A, 36A Aircraft equipped with Aeronca Thrust Reversers. Description of Change: Add Thrust ReverserOperational Changes. Filing Instructions: Insert this page adjacent to page 2 of 23 in your Thrust Reverser Supplement and retain until further notice. Add the following EXTERIOR INSPECTION to Section II - NORMAL PROCEDURES EXTERIOR INSPECTION (Power-Off) A. Inspect both thrust reversers as follows: 1. Check that thrust reverser upper and lower blocker doors are completely stowed. Change BEFORE TAKEOFF to read as follows: CAUTION: Do not operationally check thrust reversers before takeoff. 1. Thrust Reverser Circuit Breaker - In. 2. Thrust Reverser Position Indicator Lights - Extinguished. 3. Deleted. NOTE: This Temporary Change deletes Thrust Reverser Operational Check, Before Takeoff. FIGURE III TEMPORARY CHANGE, SUPPLEMENT FOR AERONCA THRUST REVERSERS Aircraft Affected: All Gates Lear Jet Model 35, 36, 35A, 36A Aircraft with Aeronca Thrust Reversers. Description of Change: Add Postflight Operational Check. Filing Instructions: Insert this page adjacent to page 4 of 23 in your Thrust Reverser Supplement and retain until further notice. Add the following POSTFLIGHT Operational Check after NORMAL PROCEDURES - After Landing: POSTFLIGHT A. Operationally check Thrust Reverser as follows: CAUTION: It is recommended that the aircraft be headed into the wind during static thrust reverser ground operational check. Keep thrust reverser deployed time to a minimum to prevent possible engine reingestion of exhaust gases. a NORM-EMER STOW Switch - NORM, EMER STOW light extinguished. b Thrust Levers - IDLE. c Thrust Reverser Levers - Pull to deploy lever stop position. UNLOCK lights will come on and then go off when DEPLOY lights come on. Check that the throttle lock releases when the DEPLOY lights illuminate. d NORM-EMER STOW Switch - EMER STOW, EMER STOW light illuminated. DEPLOY lights will go off when UNLOCK lights go on. UNLOCK lights will go off when system is stowed. eThrust Reverser Levers - Push to stow position. f NORM-EMER STOW Switch - NORM, EMER-STOW lights extinguished. g Thrust Reverser Levers - Pull to deploy position. Check for proper light sequence. h Thrust Reverser Levers - Push to stow position. Check for proper light sequence. ## Affected data sheets (1) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS A10CE](https://openairdocs.org/tcds/A10CE): Learjet Inc.; names 4 of 29 models: 35, 35A (C-21A), 36, 36A ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 211 (211 by airframe model, 0 by engine model) - Makers: Gates Learjet 136, Gates Lear Jet 50, Learjet 25 Models with the most aircraft: - [Gates Learjet 35A](https://openairdocs.org/model/gates-learjet-35a): 135 aircraft (airframe model) - [Learjet 35A](https://openairdocs.org/model/learjet-35a): 24 aircraft (airframe model) - [Gates Lear Jet 36A](https://openairdocs.org/model/gates-lear-jet-36a): 21 aircraft (airframe model) - [Gates Lear Jet 35](https://openairdocs.org/model/gates-lear-jet-35): 16 aircraft (airframe model) - [Gates Lear Jet 36](https://openairdocs.org/model/gates-lear-jet-36): 13 aircraft (airframe model) - [Learjet 35](https://openairdocs.org/model/learjet-35): 1 aircraft (airframe model) - [Gates Learjet 35A (C-21A)](https://openairdocs.org/model/gates-learjet-35a-c-21a): 1 aircraft (airframe model) All 8 models: https://openairdocs.org/ad/79-08-01-R1/models.md Every aircraft: https://openairdocs.org/ad/79-08-01-R1/aircraft.md Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB MIA97FA213](https://openairdocs.org/ntsb/MIA97FA213), Jul 15, 1997: Gates Learjet 35A (N19LH), Avon Park, FL, destroyed. Probable cause: a loss of engine power as a result of the thrust reversers being deployed and subsequent in-flight collision was wires. Factors in this accident were the pilot's disregard for procedures, and the… --- From OpenAirDocs.org, an independent open copy of FAA and NTSB data. Only the Federal Register edition on govinfo.gov is the official legal text of an AD.