AD 91-08-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | TIO-360-A1A | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | TIO-360-A1B | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | TIO-360-A3B6 | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | TIO-360-C1A6D | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-F2BD | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-J2B | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-J2BD | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-K1AD | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-N2BD | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
| engine | Lycoming Engines | LTIO-540-R2AD | TEXTRON LYCOMING Model TIO-360, TIO-540, TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series Engines |
Unsafe Condition
Engine power loss and possible loss of the aircraft due to fuel leakage from the fuel pump vent hose fitting or improper fuel pump vent restrictor fitting with orifice diameter out of limits or lacking the 'R' code letter.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform a fuel leak check at the fuel pump vent hose fitting, including disconnecting the hose, activating the boost pump, and inspecting for leakage. Replace leaking fuel pumps and recheck after replacement. Inspect and replace the fuel pump vent restrictor fitting if the orifice diameter is outside .014-.020 inch or lacks the 'R' code letter, using Loctite sealant on threads. Ensure correct orientation during reinstallation.
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Compliance Time
within the next 15 hours in service for paragraph (a) and within the next 50 hours in service for paragraph (b), after the effective date of this AD
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Affected Aircraft
Textron Lycoming TIO-360, TIO-540, LTIO-540, TIGO-541, TIO-541, and TIVO-540 Series engines with specified serial ranges; overhauled/remanufactured engines shipped before November 15, 1990; engines modified with turbochargers and induction-vented fuel pump vents.
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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