Bryan Wood
Well Known Member
Have any of you experienced a failure of your ignition/mags/starter switch? My plane is acting up and my best guess after some troubleshooting is the ignition switch.
Here are the syptoms. When the starter is engaged by turning the key past both to start the circuit breaker for the instruments pops. (I haven't looked at the wiring diagram, but assume the instrument breaker was tapped for 12v to the igition switch.) With this breaker open the starter will not engage and the prop sits there and does nothing to cool us off. Resetting the breaker and repeating offers the same outcome. The first time this happened I spent a lot of time under the panel looking for anything that could cause this, and found nothing. The cowl was pulled and the cables to the starter looked good making the problem look like the starter. Before pulling the starter I jumped 12v to the firewall mounted solenoid and the prop began to turn. This left the small wire that comes off the key switch as possibly shorted intermittantly, or the switch itself. Tracing the wire I couldn't find any nicks or measure any path to ground with my meter. Around this point everything started working and I couldn't get it to act up again. After several hours of now trying to get it to fail again I finally gave up and accepted that this would happen again and likely when we least needed it to. Well today was that day. A short joy ride to Monterey left me sitting on the ramp at Marina by myself with a plane that wouldn't start. Remembering the previous testing, I spun the key between "Off and both" about 10 times and tapped on the end of the key while it was inserted into the switch. Success! The engine started and I flew home. After shutdown in front of my hanger I tried to start the engine again and "Pop went the breaker." Abusing the key again got the plane to start. So I'm convinced enough that this switch is bad that I'm ordering a new one on Monday morning.
Is it common for these to fail? I'm wondering if one of these will be added to the list of parts to carry on trips.
Here are the syptoms. When the starter is engaged by turning the key past both to start the circuit breaker for the instruments pops. (I haven't looked at the wiring diagram, but assume the instrument breaker was tapped for 12v to the igition switch.) With this breaker open the starter will not engage and the prop sits there and does nothing to cool us off. Resetting the breaker and repeating offers the same outcome. The first time this happened I spent a lot of time under the panel looking for anything that could cause this, and found nothing. The cowl was pulled and the cables to the starter looked good making the problem look like the starter. Before pulling the starter I jumped 12v to the firewall mounted solenoid and the prop began to turn. This left the small wire that comes off the key switch as possibly shorted intermittantly, or the switch itself. Tracing the wire I couldn't find any nicks or measure any path to ground with my meter. Around this point everything started working and I couldn't get it to act up again. After several hours of now trying to get it to fail again I finally gave up and accepted that this would happen again and likely when we least needed it to. Well today was that day. A short joy ride to Monterey left me sitting on the ramp at Marina by myself with a plane that wouldn't start. Remembering the previous testing, I spun the key between "Off and both" about 10 times and tapped on the end of the key while it was inserted into the switch. Success! The engine started and I flew home. After shutdown in front of my hanger I tried to start the engine again and "Pop went the breaker." Abusing the key again got the plane to start. So I'm convinced enough that this switch is bad that I'm ordering a new one on Monday morning.
Is it common for these to fail? I'm wondering if one of these will be added to the list of parts to carry on trips.
