Shoot, Ignition Switch Not Shutting Engine Down

AKBill

AKBill

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AKBill
Shoot ignition switch not shutting engine down. After my flight this morning for some reason I tried to shut the engine down with the ignition switch. Well that didn't work.

Guessing it's the switch, wonder how much that's going to cost?
 
Be extra cautious about turning the prop after shutdown for storage. If the mags aren’t grounding or what not, it could involuntarily start by turning the prop in the direction of its rotation. Be sure to rotate it counterclockwise.
 
Craig said:
Could be a broken wire from the switch to ground. Check it out before dropping the coin on a switch.
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Agreed, just tried to look up price of switch from Textron . None in stock, contact customer service...:(
 
Ryanb said:
Be extra cautious about turning the prop after shutdown for storage. If the mags aren’t grounding or what not, it could involuntarily start by turning the prop in the direction of its rotation. Be sure to rotate it counterclockwise.
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Don't know why I tried to shut down with switch, but glad did. Guess I'm going to add that to my shutdown procedure.
 
That was my thought as well. Funny thing Textron does not recognize the part number 35-590099-3. They have a ignition switch 35-590099-37 but it's out of stock, contact customer service...:(
 
Oh, dear. The "bad ground" diagnoses again. It's 99% probable that one of the P-leads broke at the magneto during the flight. That's why you got the normal mag drops in the runup and the failure to shut off after the flight.

Those P-lead wires get shaken a lot when the engine is running, and they flex at the crimp terminals and eventually break. If it's a Bendix mag it might have the screw-cap connection, and the wire might be broken in the shield or the cap fell right off the mag.

Much less likely is a failed switch or loose wire at the switch. Don't throw money around or mess with that switch until you know what caused the failure.

Look at your mags. The affected lead might be under a rubber boot. Look to see if that wire is loose in the connector, or broken right out.
dsc00347.jpg


Or you have the round nut on a Bendix mag:

Bendix_Round_Nut-WB_grande.jpg
 
EppyGA said:
For me, trying to shut down with the mag switch wa part of the shutdown procedure.
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Same as us? Before shutdown with the mixture, we momentarily turn ignition off, check for a second, back to run.
 
Please be sure to hang a "HOT MAG" sign on the prop to protect unsuspecting line men, fuel truck drivers and anyone else who might come along and turn your hot prop.....
 
Ryanb said:
Be extra cautious about turning the prop after shutdown for storage. If the mags aren’t grounding or what not, it could involuntarily start by turning the prop in the direction of its rotation. Be sure to rotate it counterclockwise.
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No! You'll destroy your vacuum pump! I read it on the interwebz!!!!!!!!!
 
remove the switch, dissemble it and clean, reassemble, works great lasts a long time.
 
Tom-D said:
...works great lasts a long time.
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Heh, I remember the first time I heard that expression almost fifty years ago. A Lockheed tech rep came to Travis AFB to teach us the electrical components of the C-5 cargo doors. He ended every description with, "Works great and lasts a long time AS LONG AS YOU DON"T F*CK WITH IT!"

Edit: Might have been because a crew chief maunually dropped the pressure door on the ramp within a day or so of the first C-5 delivery. That wasn't supposed to be possible, but he figured out a way to eff it up.
 
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had to replace 2 of them on my travel air. I'm thinking they were around $800.00 each plus labor. its been a few years so I could be wrong.
 
I had this happen in a PA-28 during my primary training: Throttle to idle, switch to off (engine stumbles, begins to die) I released the key and the switch moved back because of the detent mechanism to the center of the OFF position, and it continued to run. The mags were not grounded unless counter-clockwise pressure on the key was maintained to hold it against the stop.

New switch installed.

New shut down procedure: Key off, hand off key, hand on key, continue....

-Skip
 
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