Stuck starter on PA28-140
Help! The starter on my 1969 Cherokee 140 is stuck in the engaged position. Anyone know what are possible causes and solutions (besides obvious R2). Note: I am a new, first-time aircraft owner so any advice is greatly appreciated.
Comments
Hi and stand by while I send this to our association A&P Erich Rempert.
Scott Sherer
Wright Brothers Master Pilot, FAA Commercial Pilot
You could try spraying some silicone lubricant on the shaft on which the pinion (small gear engaging the flywheel behind the prop) rides. This shaft can corrode over time causing the pinion to stick. This assembly (the Bendix) is separate from the actual starter motor and can be replaced at a lower cost if there is actually nothing wrong with the starter motor.
Another option is going to a newer design light weight starter.
If the starter is still engaged AFTER the engine runs, then your mechanic will have to remove the starter and have it serviced.
I hope this info helps.
Regards,
Mike
Here are the comments from our association A&P Erich Rempert:
By stuck engaged you could mean 2 things; when you turn on the master the starter starts turning the engine, or after cranking the engine the gear does not retract.
It is not merely a matter of semantics to use correct nomenclature, as well as precise and accurate language to describe your aircraft's systems and any questions or problems you encounter with them.
Doing so will greatly improve your understanding and can allow you to articulate to others in an efficient and effective manner. When you do this, you may be able to resolve issues with a simple conversation rather than with an invoice for troubleshooting!
This is a friendly suggestion and reminder to you as a new owner but also to the seasoned pilots and owners out there as well. "We all have to speak the same language"...
If the starter moves the engine whenever power is applied this is an obviously very dangerous condition and I suggest getting a mechanic involved mainly for safety reasons. But I'd begin by disconnecting the battery, then disconnecting the power input to the starter and isolating it, then reconnect the battery so you can troubleshoot the system by way of using a voltmeter.
It is likely caused by a short in the system most often due to a failed (stuck) start relay, a worn out/failed starter switch assembly, or a chafed wire. (The starter itself is probably fine)
If the gear is not retracting after starting, the spring on the Bendix cannot retract the gear for some reason. Try cleaning the nose of the starter and the bearing surfaces of the starter gear shaft with brake cleaner and then lubricating with Aerokroil or similar. Many times this will free up the Bendix and have it working like new in no time. Putting the starter through a few cycles helps with moving the lubricant into the areas where needed. If you notice sticking in the future repeat as necessary.
The other possibility is the spring is broken. If the gear shaft can be very easily moved between engaged and disengaged by hand or with a screwdriver this is a sign of failure, and you're looking at either replacement, overhaul, or repair of the starter.
If you crank the engine and it fails to start, and the gear stays engaged; this is normal behavior. Start the engine normally and then shut it down and re check the gear, it should have retracted. Lubrication as described above is acceptable preventative Maintenance for most starters, although I'd warn against washing off existing lubricants applied by the factory or overhaul shop.
As you can see a few extra words in your initial question make a dramatic difference in the answer....
Blue Skies, Tailwinds, &Cheap Avgas~
Erich Rempert, IA Consultant
Scott Sherer
Wright Brothers Master Pilot, FAA Commercial Pilot
I had an issue on a car one time. Just picked it up from the dealer. Went to restart it after driving off. The dealer had recut the key. When I went from P1 to P2 fine, but the key didn't go back to P1 when taking off the pressure. That meant the engine was started but starter motor remained engaged. When the engine remained engaged it turned the starter motor which burnt out. Key got recut.