Originally Posted by
AndyBoo
Those familiar with C152 / Lycomings / the way the ignition starters are wired:
C152's propeller turns when the master switch is on (both halves - battery + aternator) but the ignition keys are out of the ignition lock (i.e. in none of the R, L, BOTH positions or START :-). I would suspect faulty / burnt ignition switch is the culprit. Is there any other potential reason? Does this happen often (as none of the people observing the fault have seen similar thing and they do have some experience) What would happen if the engine caught up and the ignition was firing into the running engine? (i would expect there would be heaps of out of place ingintions making the engine run uneven, am I right, wrong, is there anything else?)
Thank you guys!
I think you are wrong. If the engine did fire the spark could only come from the magneto(s) which is mechanically driven from the engine with a fixed relationship between cylinder position and spark.
But I would highly doubt if it would fire for the same reason - without the mags on there is no source of spark. I imagine the problem can only be some kind of short with the starter circuit.