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Lycoming or Continental aircraft engine quits on landing or with throttle off

1. Rich mixture. The engine can handle a rich mixture better when it is at power than at idle. Rich mixtures are accompanied by sooty spark plugs and exhaust stack, rough idle, and black smoke. Check mixture. On Marvel Schebler carbureted engines the old style composite floats will sometimes absorb fuel thereby becoming heavy. This raises the fuel in the float below causing the engine to run rich. Fuel may drip out of carburetor into air box. Rich mixtures can contribute to hard starting after the engine quits at idle. This can be especially hazardous during the landing phase of flight or during pilot training exercises. The Beech Sundowner when it first came out had this problem until the carburetor was re-jet'd

For Cessna 172 aircraft see Cessna Service Bulletin SB01-11-02 or latest revision. Also consult Airworthiness Directive 2001-06-14 or latest revision.

2. Continental fuel injected engines; Linkage wear occurs in metering arms. Throttle advance causes throttle butterfly to move but due to play in the linkages, the metering valve doesn't move right away, so the idle mixture is upset and the engine quits.

forced landing

3. Continental IO-240-B engines: Comply with Continental Service Bulletin SB04-4A or latest revision. This bulletin
is about "reports of engine instability and occasional engine stoppage at low idle speeds during rollout." It provides instructions for the replacement of the manifold valve spring PN 630184 with spring PN 627379.

4. Fuel line leak. Hose pictured below shows signs of fuel leakage.

aircraft hose leak

This leaking hose produced the following symptoms in a Mooney M20K with a TSIO-360-GB4 engine.

  • Engine gradually needed more prime and throttle to start.

  • After about 25 hours then engine slowed down and quit during taxi. Restarted fine.

  • At 5,500 feet engine slowed down and stopped. Able to restart

  • Engine stopped again and was able to restart.

This hose has the orange Firesleeve and is sealed and clamped at both ends. The hose developed a leak but most of it was contained within the Firesleeve. The dark staining is caused by the gasoline soaking thru the Firesleeve.

A close-up of the staining:

aircraft hose leak

The dark color is not normal and indicates that the hose under the Firesleeve is leaking. As part of your inspection, if you notice a hose with strange staining, it is probably bad.

5. Manifold pressure line leak may cause the engine to quit on landing or slow idle.

 

 

 

 

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Disclaimer: sacskyranch.com contains abundant information relating to aircraft maintenance. The information provided  is not intended to supercede or supplement the F.A.A. approved  maintenance and/or operator’s manuals. Those F.A.A. approved manuals must be utilized when performing maintenance and/or operating aircraft.