Failed starter

[Matthew]

The starter on our club 150 failed on Saturday. It wouldn't retract/disengage. The other guys in the club who handle the maintenance will get it taken care of, soon, we hope. Meanwhile, I'm just curious.

The symptoms started with it not wanting to engage (it would spin, but the gear wouldn't extend to engage the flywheel). After a couple of tries, it did start working, but then wouldn't disengage. We shut everything down, removed the cowl, and turned the prop over by hand a couple of times but couldn't get it to retract.

Probably will need a new starter, but any ideas on what happened inside?

 

[Cap'n Jack]

I've heard it could be as simple as junk fouling it...beyond that- I really don't know.

 

[ScottM]

I have had the before. A cleaning and lube solved it. Well for a while. I got tired of it happening for the third time and opted to replace the starter with a Skytec model.

Until that replacement occurred I always carried a can of silicon lube to loosen up the gear.

 

[gprellwitz]

I always carried a can of silicon lube to loosen up the gear.

That's what they all say!

 

[Tom-D]

The starter on our club 150 failed on Saturday. It wouldn't retract/disengage. The other guys in the club who handle the maintenance will get it taken care of, soon, we hope. Meanwhile, I'm just curious.

The symptoms started with it not wanting to engage (it would spin, but the gear wouldn't extend to engage the flywheel). After a couple of tries, it did start working, but then wouldn't disengage. We shut everything down, removed the cowl, and turned the prop over by hand a couple of times but couldn't get it to retract.

Probably will need a new starter, but any ideas on what happened inside?

There are two types of starters on a 150, do you have a key start or a pull starter?

 

[Matthew]

There are two types of starters on a 150, do you have a key start or a pull starter?

It's a key-start (150/150), don't know the engine type. The starter gear is visible, just above the cowl opening on the left-seat side. One of the first things we did was to move the prop in such a way as to relieve pressure on the teeth of the starter gear. Even with no pressure, the gear wouldn't retract. One of the guys tried tapping (gently) on the gear, he also tried pushing and said it felt like it was springing back out (into the engaged position). I think one of the guys checked and said the starter had been replaced about 5 years ago - but none of the three of us were around then and don't know if it was new or used.

The trouble started when it showed signs of not wanting to engage, then it engaged, and now it's stuck in the engaged position. I've never taken one apart, so I'm not exactly clear on how the inner mechanisms work. Just trying to get a better understanding of the innards.

 

[Dan Thomas]

It's a key-start (150/150), don't know the engine type. The starter gear is visible, just above the cowl opening on the left-seat side. One of the first things we did was to move the prop in such a way as to relieve pressure on the teeth of the starter gear. Even with no pressure, the gear wouldn't retract. One of the guys tried tapping (gently) on the gear, he also tried pushing and said it felt like it was springing back out (into the engaged position). I think one of the guys checked and said the starter had been replaced about 5 years ago - but none of the three of us were around then and don't know if it was new or used.

The trouble started when it showed signs of not wanting to engage, then it engaged, and now it's stuck in the engaged position. I've never taken one apart, so I'm not exactly clear on how the inner mechanisms work. Just trying to get a better understanding of the innards.

Now, you have either a Cessna 152 or a 150 with a Lycoming STC'd into it. The Cessna 150 originally had its starter on the back of the engine and out of sight.

The starter gear on a Lycoming locks into the engaged position until the engine starts and spins the gear fast enough to release the engagement locks. If the engine hasn't run since the last start attempt, what you see is normal. If the gear is reluctant to engage, that too is usual but due to crud and lack of the proper lube. Dry silicone spray lube is the only thing to use on those, and it's hard to get into the thing without taking the cowl off and shooting it into the hole in the bottom of the starter drive housing. If someone used oil on it, the oil has attracted dust and created sticky sludge that causes sticking.

Dan

 

[Matthew]

Now, you have either a Cessna 152 or a 150 with a Lycoming STC'd into it. The Cessna 150 originally had its starter on the back of the engine and out of sight.

The starter gear on a Lycoming locks into the engaged position until the engine starts and spins the gear fast enough to release the engagement locks. If the engine hasn't run since the last start attempt, what you see is normal. If the gear is reluctant to engage, that too is usual but due to crud and lack of the proper lube. Dry silicone spray lube is the only thing to use on those, and it's hard to get into the thing without taking the cowl off and shooting it into the hole in the bottom of the starter drive housing. If someone used oil on it, the oil has attracted dust and created sticky sludge that causes sticking.

Dan

Pretty sure it's a 150 with the STC engine mod. This would have been about the 4th engine start of the day. The guy who was starting it got the engine to catch, then shut it down right away. He got out and immediately looked at the starter, so something got his attention. He said the starter wasn't releasing.

The engaged postion is normal when the engine isn't running? I've never paid that much attention to it before.

 

[jesse]

The engaged postion is normal when the engine isn't running? I've never paid that much attention to it before.

It sounds like the engaged position is only normal if you tried to start it and it failed to spin fast enough to disengage.

If you started the engine successfully and shut it down - if everything was working properly - the starter wouldn't be engaged.

 

[Matthew]

It sounds like the engaged position is only normal if you tried to start it and it failed to spin fast enough to disengage.

If you started the engine successfully and shut it down - if everything was working properly - the starter wouldn't be engaged.

Yeah - it took me a while to re-think that and realize that's what he was probably getting at.

I dunno - maybe the starter is OK after all. But the guy who was trying to start the engine sure shut it down in a hurry because he thought something was wrong.

I haven't heard back from anybody yet on what, if anything, was found. We're expecting rain most of the week, and the plane sits in an open sided hangar, so it may be a while before anybody who knows what they are doing gets around to looking at it.

 

[Steve]

If there's any doubt about the condition of the starter, pull it, inspect it, clean it and lubricate it. It probably got the way it is by no one taking the time to do a little preventative maintenance on a routine basis.

 

[Dan Thomas]

Yeah - it took me a while to re-think that and realize that's what he was probably getting at.

I dunno - maybe the starter is OK after all. But the guy who was trying to start the engine sure shut it down in a hurry because he thought something was wrong.

I haven't heard back from anybody yet on what, if anything, was found. We're expecting rain most of the week, and the plane sits in an open sided hangar, so it may be a while before anybody who knows what they are doing gets around to looking at it.

If the engine reached idle RPM and the starter didn't disengage, there are two possibilites: A) the starter gear is stuck in the engaged position, or b) the starter contactor is stuck on.

If the contactor was stuck, the starter would continue cranking after the mixture was pulled and wouldn't stop until the master was shut off. Not the likely scenario here. I would think the starter bendix is shot or seized or gunked up real bad after someone used oil on it.

Dan

 

[rpadula]

It's a key-start (150/150), don't know the engine type. The starter gear is visible, just above the cowl opening on the left-seat side.

Is it kept outside or in a hangar?

I have heard that this placement makes it easier for gunk to get into the starter drive (windblown rain, dust, pollen, etc). Can anyone confirm?

 

[Matthew]

Is it kept outside or in a hangar?

I have heard that this placement makes it easier for gunk to get into the starter drive (windblown rain, dust, pollen, etc). Can anyone confirm?

It's in an open hangar - roof only.

 

[Steve]

I do know on my Lycoming there is a low pressure area behind the spinner bulkhead that pulls any engine oil leakage, including spillage from adding oil, toward the front of the engine case and onto the starter ring gear where it can enter the starter nose assembly. Before overhaul I had the same problem with a sticking starter gear, changed out the starter with a factory new one from Kelly Aerospace and guess what, the new one did exactly the same thing. After some tedious cleaning of all the ring gear teeth with Q-tips and degreaser the problem went away. The current overhauled engine is much cleaner with no visible oil leaks, but I'm keeping an eye on the ring gear for recurrence. Discussions with Kelly Aerospace tech support indicated liberal use of silicone spray lubricant on the starter internals is advisable, however, I end up cleaning it off the windshield for several flight hours after doing so, so I know the airflow around the starter gear is involved in contaminating the ring gear.

Is it kept outside or in a hangar?

I have heard that this placement makes it easier for gunk to get into the starter drive (windblown rain, dust, pollen, etc). Can anyone confirm?