AD 87-04-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Learjet Inc. | 35 | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 35A (C-21A) | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 36 | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 36A | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 55 | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 55B | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
| aircraft | Learjet Inc. | 55C | Airworthiness Directives; Gates Learjet Model 35, 35A, 36, and 36A, 55 Series Airplanes |
Unsafe Condition
Potential for operations with unsafe flight director steering commands due to unaddressed VOR enroute and approach operations limitations.
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Required Actions
Insert specific limitations and notes in the AFMS, including prohibiting flight director VOR enroute and approach operations, and revising flap requirements for autopilot VOR approaches. Use temporary TFM Supplements until approved changes are installed. Install Gates Learjet Service Bulletins SB35/36-22-5 or SB55-22-2 as terminating actions.
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Compliance Time
within the next 10 hours time-in-service after the effective date of this AD
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Affected Aircraft
Gates Learjet Models 35, 35A, 36, 36A, and 55 series airplanes equipped with specific J.E.T. autopilot/flight directors, with serial ranges as specified in the AD for Model 55 (S/N 55-003 through 55-126) and exceptions for certain serial numbers and modifications.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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