View Full Version : Primer?
Dnathan
9th Feb 2006, 14:19
Hi.
I was wondering if anybody knew why the primer on most 4 cyl. piston engine aircraft is attached only to three of the cylinders?
I posted the same question in maintenance a couple of weeks without any luck in responses.
Happy flying.
FlyVMO
9th Feb 2006, 16:00
Could be wrong, its been a while,
but I believe the relevant hole is drilled in all the cylinder heads, but is used for something else on one cylinder, I think CHT probe. If I get time I'll try and look it up.
FlyVMO
potkettleblack
9th Feb 2006, 16:27
This was one of those questions that got you thinking how little you know about the aircraft you fly so I got searching.
Found the following link which was of interest:-
http://www.lycoming.textron.com/main.jsp?bodyPage=/support/publications/keyReprints/operation/coldWeather.html
Basically the article states that no two aircraft are necessarily the same and the number of cylinders that have priming lines is down to the manufacturer. I guess some of the old nags I have struggled to get started on a cold morning might have only had 1??
Was told years ago that it prevents flooding of all cylinders in case of
a little over enthousiastic priming.
Would still give you a chance to start...hopefully.
Don't know if it's the official reason, but it does make sense.