uwochris
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- Joined
- Dec 21, 2001
- Posts
- 381
Hey guys,
I have some Qs regarding engine start procedures.
For the 172 I used to fly (fuel injected), the basic procedure was:
- master on.
- throttle set.
- fuel pump on.
- mixture rich, then idle (I assume this is to prime??).
- fuel pump off.
- crank, and set mixture rich once it fires.
For the C1 I used the fly (also fuel injected, but Continental engine is used), the procedure was:
- master on.
- mixture rich.
- fuel pump on.
- fuel prime on (separate switch).
- throttle full forward, then set (this is to prime).
- crank and start.
Now, I do not know why the mixture can be full rich in one case, and should not be full rich in the other. Would it even make a difference for the 172 if I left the mixture to rich when I cranked it? I personally do not think so because the checklist calls for you to turn the fuel pump off for the start, but I am obviously missing something here because the engine would likely get flooded if you left it rich. (ie. with the engine not yet running and the fuel pump off, the mixture control should not have any affect whatsoever, or at least this is what I thought).
In the 152 I fly now (carburreted), the mixture is always rich for the start. Again, does anyone know why this is the case, if both the 172 and 152 use Lycomings?
Thanks in advance.
Chris.
I have some Qs regarding engine start procedures.
For the 172 I used to fly (fuel injected), the basic procedure was:
- master on.
- throttle set.
- fuel pump on.
- mixture rich, then idle (I assume this is to prime??).
- fuel pump off.
- crank, and set mixture rich once it fires.
For the C1 I used the fly (also fuel injected, but Continental engine is used), the procedure was:
- master on.
- mixture rich.
- fuel pump on.
- fuel prime on (separate switch).
- throttle full forward, then set (this is to prime).
- crank and start.
Now, I do not know why the mixture can be full rich in one case, and should not be full rich in the other. Would it even make a difference for the 172 if I left the mixture to rich when I cranked it? I personally do not think so because the checklist calls for you to turn the fuel pump off for the start, but I am obviously missing something here because the engine would likely get flooded if you left it rich. (ie. with the engine not yet running and the fuel pump off, the mixture control should not have any affect whatsoever, or at least this is what I thought).
In the 152 I fly now (carburreted), the mixture is always rich for the start. Again, does anyone know why this is the case, if both the 172 and 152 use Lycomings?
Thanks in advance.
Chris.