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View Full Version : CFI Pop Quiz #319 - Fuel Grade

Chris Burgess
03-19-2006, 03:09 AM
If the grade of fuel used in an aircraft engine is lower than that specified, it may cause

A) detonation.
B) lower cylinder head temperatures
C) a decrease in power which could overstress internal engine components.
Butch S.
03-19-2006, 03:25 AM
A) detonation

D) higher head temps
E) ring land & big end damage

Butch S.
SamL
03-19-2006, 03:26 AM
"A", and it will depend on your compression ratio.
EI-GYRO
03-19-2006, 03:03 PM
A 4 me 2........
birdy
03-19-2006, 04:53 PM
You get wot you pay for.
If you pay cheap, you get cheap. But, you will get for free, all the consiquenses that go with it.
Paul_Zurawski
03-20-2006, 02:49 AM
Alpha 4 me
brett s
03-20-2006, 07:24 AM
A...

Used to work for a guy that ran 93 octane auto gas in a high compression VO-540 - he'd been using it for years in VO-435's in Bell 47's, they didn't have any trouble. The 540 was a different story, low power settings were ok but pull more than 22" MP for any length of time & things got ugly. He got away with it for a while because in ag work high power was only used for a minute or so on takeoff...
Chris Burgess
03-21-2006, 04:00 AM
Most correct answer, "A". If the grade of fuel used in an aircraft engine is lower than that specified, it may cause (A) detonation. Reference FAA-H-8083-25


"B" (lower cylinder head temperatures) is incorrect because a lower grade of fuel will cause higher cylinder head temperatures. "C" (a decrease in power which could overstress internal engine components) is incorrect because this is the result of detonation.