AD 91-03-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Learjet Inc. | 31 | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 35 | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 35A (C-21A) | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 36 | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 36A | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 55 | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 55B | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
| aircraft | Learjet Inc. | 55C | Airworthiness Directives; Learjet Model 31, 35/35A, 36/36A, 36/36A and 55/55B/55C Series Airplanes |
Unsafe Condition
Electromagnetic interference, and smoke and/or fire in the cabin due to specific inverters: Aerospace Lighting Corporation P/N 18.95(); Instrument and Flight Research P/N 25-415-3-0L or 250001-240G; or Precision Winding, Incorporated P/N 6900092 or 6900054-54.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Deactivate cabinet and overhead fluorescent lighting systems, fabricate and install placards on deactivated circuit breakers per Learjet Alert Service Bulletins 31-33-2A (Model 31), 35/36-33-5A (Models 35/35A/36/36A), and 55-33-3A (Models 55/55B/55C).
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 25 hours time-in-service after the effective date of this AD
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Affected Aircraft
Learjet Model 31 (S/N 001-023); Model 35/35A (S/N 001-661); Model 36/36A (S/N 001-059, 062, 063); Model 55/55B/55C (S/N 001-144) with specified inverters: ALC P/N 18.95(), IFR P/N 25-415-3-0L/250001-240G, or Precision Winding P/N 6900092/6900054-54.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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