Intermittent failed mag test

·         Israel

·         Topic Author

·         Offline

·         Posts: 2

·         

·         

·         

Intermittent failed mag test
I have not long purchased a Just aircraft escapade fitted with a 2200A it has coming up 300 hours on it and runs very nice. #22A2477
But an intermittent fault has started when doing the mag check.
When switching off the left mag the engine stops but if you wait a minute and start it again and retest its fine? It has done it 3 times in the last 25 hours the tests after landing are fine.
You can’t pick up any difference in running from one to the other it sounds fine.
I changed out the right mag switch but it did it again a few days later.
How do the coils fail? Outright or in this way?
Next time I will but a meter across the switch to see if it is shorted out.

Please Log in or Create an account to join the conversation.

·         Doug Smith

·         

·         Offline

·         Posts: 287

·         

Hi Israel,
Intermittent failures like that aren't unusual in the coils. That said, it's worth doing the basic troubleshooting on the switches, wiring etc. Just swapping the switch wire from one coil to another is a good start, see if the fault moves with the wires or stays with the coil.
Regards,
Doug.

Please Log in or Create an account to join the conversation.

·         Israel

·         Topic Author

·         Offline

·         Posts: 2

·         

·         

·         

I thought i had found the fault the other week when it failed the mag test I tested across the mag switch to find it shorted in the open position I removed the wire that went from the mag switch to the rev-counter and it went away.
So I put switch in line to disconnected the rev-counter and it had been ok until Sunday.
But a least now it is failed out right.
Swapped the wires on the coils and it moves switches so I am picking its is a coil fault.
But the coil still reads within the resistance levels in the manual.
Any ideas would be help full
Thanks

Please Log in or Create an account to join the conversation.

·         Doug Smith

·         

·         Offline

·         Posts: 287

·         

Well, assuming the coil gaps are good then I'm guessing you've had a failure in the switching circuitry of the coil - there are various items of electrical black magic in there which can fail and leave the resistances within limits. Sounds like time for a new one!
D.

Please Log in or Create an account to join the conversation.