Ramifications of a Stuck Starter?

Erice

Erice

Pre-takeoff checklist
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Erice
We had a situation with the Cessna 150 I help operate that presented itself as an overcharging situation. The radios, transponder, then strobe and beacon all quit in flight. The student pilot and CFI returned to land and shut down. Total Hobbs time = 0.2, but total tach time was 0.4 (I've never seen tach time > hobbs time before). No electrical parts were working. They figured it was a bad voltage regulator or alternator, which may have ruined the battery.

When I got back in town a couple of days later, I went to investigate the situation. I flipped the master switch on (no keys in the bendix ignition switch), and the prop immediately started cranking. I quickly turned off the master, and sat there thinking of what to do. I went and got the keys, put them into the switch, flipped on the master, and jostled the key a bit. This stopped the cranking of the propeller. I assume this means I have a bad bendix switch. Come to think of it, I never switched the radios on. I wonder if they still work.

My first thought was to start up the engine, and fly it over to the A&P's location with the master switch off, in case the starter fails to disengage. When I called up him up, he said he was concerned that running the engine with a stuck starter might have caused the engine to "make metal." He recommends draining the engine oil through a fine screen, and cutting open the oil filter to check for metal fragments. This has me worried, but I'd rather sacrifice 5 quarts of oil and a filter for peace of mind that the engine is OK.

I was just wondering if anyone here might explain why a running the engine with a stuck starter could cause an engine to make metal? Are there other things the A&P and/or I should check? Is this overkill?

What should a pilot see/hear/notice that would indicate that a starter failed to disengage after the engine is running?
 
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Erice said:
We had a situation with the Cessna 150 I help operate that presented itself as an overcharging situation. The radios, transponder, then strobe and beacon all quit in flight. The student pilot and CFI returned to land and shut down. Total Hobbs time = 0.2, but total tach time was 0.4 (I've never seen tach time > hobbs time before). No electrical parts were working. They figured it was a bad voltage regulator or alternator, which may have ruined the battery.

all it can do is run the battery down.

When I got back in town a couple of days later, I went to investigate the situation. I flipped the master switch on (no keys in the bendix ignition switch), and the prop immediately started cranking.

The only way this can happen is when the switch is in the start position Electrically.

I quickly turned off the master, and sat there thinking of what to do. I went and got the keys, put them into the switch, flipped on the master, and jostled the key a bit. This stopped the cranking of the propeller.

that means the switch is bad and not disconnecting the starter relay from the buss

I assume this means I have a bad bendix switch. Come to think of it, I never switched the radios on. I wonder if they still work.

yep…. the radios should work when the battery is charged.

My first thought was to start up the engine, and fly it over to the A&P's location with the master switch off, in case the starter fails to disengage. When I called up him up, he said he was concerned that running the engine with a stuck starter might have caused the engine to "make metal." He recommends draining the engine oil through a fine screen, and cutting open the oil filter to check for metal fragments. This has me worried, but I'd rather sacrifice 5 quarts of oil and a filter for peace of mind that the engine is OK.

the key start starter can not be spun by the engine, it is a prawl that when driven from wrong direction opens the prawl and disconnect the starter. this will not cause any wear in the engine or prawł

I was just wondering if anyone here might explain why a running the engine with a stuck starter could cause an engine to make metal? Are there other things the A&P and/or I should check? Is this overkill?

the 150 with key start will not..

What should a pilot see/hear/notice that would indicate that a starter failed to disengage after the engine is running?
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The 152 with the Lycoming with a bendix type starter will fail to retract the drive gear from the ring gear on the flywheel and it makes a big ringing noise you will hear it even under the head set.
 
If the starter does not disengage, you want to shut it right down and leave it shut down until the problem is resolved. Failure to do so can ruin the starter and ring gear as well as overcharge the electrical system because the starter is then operating as an unregulated generator.

And while I've never before heard of a starter engaging in flight, I suppose with the right fault it's possible, and if it did, you would want to put it on the ground as soon as practical for inspection and repair before further flight.
 
Ron Levy said:
If the starter does not disengage, you want to shut it right down and leave it shut down until the problem is resolved. Failure to do so can ruin the starter and ring gear as well as overcharge the electrical system because the starter is then operating as an unregulated generator.
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When this happened on our club 150, the pilot on the controls shut down as soon as he felt something was wrong. I don't know all the details, but the potential problem that that Ron just gave was also metnioned at the time.
 
Thanks for all the tips.

I went and checked out the radios. The comm radio transmits and receives. The nav radio tuned in a local VOR, and I could hear the morse code ID. The transponder lit up, and appears to be OK. I think I'll to put a charger on the battery to bring it back up to a full charge.

I still am going to have a mechanic check it out. But from what Tom said, it might be unnecessary to drain the oil/cut the filter, right?
 
Ron Levy said:
If the starter does not disengage, you want to shut it right down and leave it shut down until the problem is resolved. Failure to do so can ruin the starter and ring gear as well as overcharge the electrical system because the starter is then operating as an unregulated generator.

And while I've never before heard of a starter engaging in flight, I suppose with the right fault it's possible, and if it did, you would want to put it on the ground as soon as practical for inspection and repair before further flight.
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On the C-150/0-200 key start, it is impossible for the engine to drive the starter.

When you understand the operation of a prawl mechanism you'll understand it can only be driven in one direction.

the starter motor can run until dooms day, but as long as the engine is spinning the starter shaft faster than the starter motor, it will not engage.
 
Matthew said:
When this happened on our club 150, the pilot on the controls shut down as soon as he felt something was wrong. I don't know all the details, but the potential problem that that Ron just gave was also metnioned at the time.
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Your 150 was not a key start, or it was a 152.. because if the engine was running and the starter was in fact spinning the pilot would never know it until the engine was shut down by the mixture, then the starter would continue to crank the engine until the master was shut off.

If your 150 was a pull start, it is possible to break the disengage spring and leave the starter engaged into the engine starter gear. but not a key start.
 
Tom-D said:
Your 150 was not a key start, or it was a 152.. because if the engine was running and the starter was in fact spinning the pilot would never know it until the engine was shut down by the mixture, then the starter would continue to crank the engine until the master was shut off.

If your 150 was a pull start, it is possible to break the disengage spring and leave the starter engaged into the engine starter gear. but not a key start.
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I don't know what kind of start that plane has - I've never flown it. It does have the worm gear that extends out onto the flywheel, though, I did see that, and that is the part that wouldn't retract. I don't know how he knew that something was wrong, but he did get some feedback somewhere that told him that something wasn't right. I remember that we did need a new starter.
 
Erice said:
Thanks for all the tips.
YAVW
I went and checked out the radios. The comm radio transmits and receives. The nav radio tuned in a local VOR, and I could hear the morse code ID. The transponder lit up, and appears to be OK. I think I'll to put a charger on the battery to bring it back up to a full charge.

That is exactly what you should do..

I still am going to have a mechanic check it out. But from what Tom said, it might be unnecessary to drain the oil/cut the filter, right?
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when you get the battery back up to charge try starting it, if it starts you are good to go after a ignition switch replacement.

just remember the key start prawl runs in contact with the starter drive shaft at all times, but it will not grip the drive shaft until it is spinning faster than the drive shaft. then it will grip the shaft and spin the engine.

the prawl mechanism is totally different than a bendix gear mechanism, the bendix gear mechanism can fail and leave the two gears engaged the prawl runs in contact at all times and is fed pressure oil from the engine oil system.

when a key start starter prawl mechanism fails it will not engage the shaft then starter spins and the engine doesn't.. I'm sure that any one with time in a C-150/0-200 with a key start has had this happen when using Areoslime 15W50 with the Lycoming snake oil additive in it. The additive is TCP, that is a polishing agent that wears the prawl segments until they no longer grip the starter drive shaft and cause the failure of the starter prawl mechanism.
 
Matthew said:
I don't know what kind of start that plane has - I've never flown it. It does have the worm gear that extends out onto the flywheel, though, I did see that, and that is the part that wouldn't retract. I don't know how he knew that something was wrong, but he did get some feedback somewhere that told him that something wasn't right. I remember that we did need a new starter.
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That's a Lycoming 0-235. totally different that any Continental.

because he heard the big ringringringrinring noise.

OBTW that aircraft is a 152.. :)
 
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Tom-D said:
That's a Lycoming 0-235. totally different that any Continental.

because he heard the big ringringringrinring noise.

OBTW that aircraft is a 152.. :)
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Good call, yeah - it's not a stock 150. It's a 150 with a 150hp conversion.
 
We've had starters hang up when the starter solenoid welded itself shut. They'll do that when they get worn and the contacts burn a bit; that generates enough heat to weld them together.

If the starter keeps running like that it gets really hot. The commutator has copper segments embedded in a resin, and the resin lets go with the heat and throws the segments. Totally ruins the starter. Some guys will crank a cold or flooded engine until the starter does that, too. A starter has no cooling system and it's easy to abuse it.

If a Lycoming starter sticks it chews the ring gear all to bits, not to mention the starter gear. But that's a whole lot cheaper to fix than a failed Continental drive that drops chunks of metal into the engine.

A hung starter could burn out the alternator, too. The starter current doesn't pass through the ammeter, but it still runs the battery way down and the alternator ends up chasing it and pumping out more amps than it was designed for. Alternators don't have the current limiter in the regulator that the old generators did; the alternator is sized to take all the constant-current loads in the airplane, but the starter draws far more than that.


Dan
 
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Tom-D said:
that doesn't compare with a 0-200.
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I'll have to dig into the paperwork and see just what it does have. I've always been told it's a 150/150, but I don't know anything about engine model numbers.
 
What do you make, then, of the electrical system draining itself down to nothing?
 
Erice said:
What do you make, then, of the electrical system draining itself down to nothing?
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the ignition switch left the starter relay connected to the bus, and ran the battery down. it can do that with a high resistance connection and not rotate the engine.

but when the master switch was shut off the bus was disconnected it would stop the current flow to the starter relay. which is a solenoid drawing current all the time the master is on. (during this discrepancy)

after setting from one flight to the next the battery regenerates a little, so when the master is turned on the engine cranks.
 
Dan Thomas said:
We've had starters hang up when the starter solenoid welded itself shut. They'll do that when they get worn and the contacts burn a bit; that generates enough heat to weld them together.

If the starter keeps running like that it gets really hot. The commutator has copper segments embedded in a resin, and the resin lets go with the heat and throws the segments. Totally ruins the starter. Some guys will crank a cold or flooded engine until the starter does that, too. A starter has no cooling system and it's easy to abuse it.

If a Lycoming starter sticks it chews the ring gear all to bits, not to mention the starter gear. But that's a whole lot cheaper to fix than a failed Continental drive that drops chunks of metal into the engine.

A hung starter could burn out the alternator, too. The starter current doesn't pass through the ammeter, but it still runs the battery way down and the alternator ends up chasing it and pumping out more amps than it was designed for. Alternators don't have the current limiter in the regulator that the old generators did; the alternator is sized to take all the constant-current loads in the airplane, but the starter draws far more than that.


Dan
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The key start starter prawl is totally contained in its housing, and can not shed any parts into the accessory case, Total impossibility, that's an old wives tale of the old pull starter gears carried over to the key start.

It simply can't happen..
 
Matthew said:
I'll have to dig into the paperwork and see just what it does have. I've always been told it's a 150/150, but I don't know anything about engine model numbers.
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If it is a 150/150 it has a 0-320/150 horse, which is the big brother to the 0-235, same starter style with bendix type starter running a ring gear on the flywheel.
 
Tom-D said:
The key start starter prawl is totally contained in its housing, and can not shed any parts into the accessory case, Total impossibility, that's an old wives tale of the old pull starter gears carried over to the key start.

It simply can't happen..
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Sorry to burst everyone's bubble bit it can happen. I've seen several over the years. Charlie Melot Zephyr Engines
 
Been a while since I was in an O200 but I thought the key type starter had a solenoid to kick two gears into mesh?
 
charlie said:
Sorry to burst everyone's bubble bit it can happen. I've seen several over the years. Charlie Melot Zephyr Engines
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I've changed probably 100+ key start clutches for wear, but never seen a key start clutch come apart.

Any gear can drop a tooth, but as far as the prawl segments getting out of the housing, it would be a vary rare occasion, and I don't see how a segment could tear the steel housing enough to escape.
 
Skylane81E said:
Been a while since I was in an O200 but I thought the key type starter had a solenoid to kick two gears into mesh?
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nope the 2 gears run fully engaged all the time. the prawl is what engages the drive shaft of the larger gear and connects the spinning starter motor to the gear.

The pull starter has 2 gears that separate. much like a bendix.
 
Tom-D said:
The key start starter prawl is totally contained in its housing, and can not shed any parts into the accessory case, Total impossibility, that's an old wives tale of the old pull starter gears carried over to the key start.

It simply can't happen..
Click to expand...

I had an O-200 starter drive that had split that little housing and dropped the pawls into the accessory case. And I've had the ball bearing in the starter drive in the Continental O-470 fail and drop balls into the case, too.

When an engine kicks back it can easily overload the drive far beyond what it was designed to take. Some of the new PM starters have a shear pin to save things if overload occurs.

Dan
 
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Dan Thomas said:
I had an O-200 starter drive that had split that little housing and dropped the pawls into the accessory case. And I've had the ball bearing in the starter drive in the Continental O-470 fail and drop balls into the case, too.

Dan
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what would cause the prawl segments to break the housing? They are arranged radially around a 1/2" shaft on a gear, there is nothing to force them outward enough to cause them to hit the housing.

the 0-470 angle starter drive is a separate self contained unit, how can the balls get into the case?
 
Tom-D said:
what would cause the prawl segments to break the housing? They are arranged radially around a 1/2" shaft on a gear, there is nothing to force them outward enough to cause them to hit the housing.

the 0-470 angle starter drive is a separate self contained unit, how can the balls get into the case?
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The pawls push outward on the housing they're in. They wedge between that housing and the shaft, producing enormous pressure on the housing.

The O-470's bits did make it into the case and oil pan. There's room, especially once the bearing fails and the shaft flops around, making room between the gear and case.
 
Picture # 2 is a 0-470 angle drive for the vac pump and starter. fully self contained unit.

picture number #1 is a 0-200 clutch the big gear spins when driven by the starter motor, the little gear spins with the engine at all times the steel bellows between them is the prawl mechanism.
 

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Dan Thomas said:
The pawls push outward on the housing they're in. They wedge between that housing and the shaft, producing enormous pressure on the housing.

that shaft is only .500" ("1/2") how far can it push? that simply doesn't make sense.

The O-470's bits did make it into the case and oil pan. There's room, especially once the bearing fails and the shaft flops around, making room between the gear and case.
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the shaft sticking out of the angle drive unit goes into a seal and bearing in the engine case, so how can a bearing in the angle housing get into the case?

most of the info is here

http://www.sacskyranch.com/eng39.htm
 
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Tom-D said:
the shaft sticking out of the angle drive unit goes into a seal and bearing in the engine case, so how can a bearing in the angle housing get into the case?

most of the info is here

http://www.sacskyranch.com/eng39.htm
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Ball bearing (number 46) fails. Balls fall out.


tcmstarter.gif


The balls find their way through the holes in the gear.

StarterAdapter10.jpg



Then they go through the oil drain hole into the accessory case. The hole here is to the right of the drive gear.

StarterAdapter05.jpg



Once in the case they can cause all sorts of havoc.

Dan
 
In all the years I have never seen that happen..
 
Tom-D said:
In all the years I have never seen that happen..
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No, it's not often, for sure. It was on an infrequently-flown airplane where corrosion inside the engine can do nasty things. The ball bearing had corroded enough to crumble a couple of those small balls, and after that it just fell apart.

I've seen it in an old Bendix magneto, too, on a 170 based at the same airport. Ball bearing in the front of the mag fell apart. The balls went into the mag, thankfully, not the case.

Dan
 
Dan Thomas said:
I had an O-200 starter drive that had split that little housing and dropped the pawls into the accessory case. And I've had the ball bearing in the starter drive in the Continental O-470 fail and drop balls into the case, too.

When an engine kicks back it can easily overload the drive far beyond what it was designed to take. Some of the new PM starters have a shear pin to save things if overload occurs.

Dan
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Skytec did this, found on the small bore TCM starter that the pin was too small, solution was bigger hole for bigger pin.

Result: shaft failure rather than broken pin.

New solution is a clutched starter. Looking forward to trying it.
 
Dan Thomas said:
No, it's not often, for sure. It was on an infrequently-flown airplane where corrosion inside the engine can do nasty things. The ball bearing had corroded enough to crumble a couple of those small balls, and after that it just fell apart.

I also get the feeling that the angle starter drive on that engine wasn't overhauled at the last major. one of the hazards of run to failure. in most cases the bearing failure leads to no start, and the angle drive gets overhauled long before a failure of the bearing degrades to a point of escaping the cage.

I've seen it in an old Bendix magneto, too, on a 170 based at the same airport. Ball bearing in the front of the mag fell apart. The balls went into the mag, thankfully, not the case.

the advantage of having magnets in the mag.. :)

Dan
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Now you know why the manufacturers have a TIME between overhauls.
 
Skylane81E said:
Skytec did this, found on the small bore TCM starter that the pin was too small, solution was bigger hole for bigger pin.

Result: shaft failure rather than broken pin.

New solution is a clutched starter. Looking forward to trying it.
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I've bought several of these Skytecs in the last year or two:

NLLogowStarter.gif


I've tried Skytec, Lamar, Magnaflite and Kelly starters. This Skytec is the best by a wide margin. It doesn't rely on inertia to engage the gear or latches to keep it engaged or weak springs (that break) to retract the gear or spiral splines that sludge up and stick, and it has no front bronze shaft support bushing that gets dirty and wears out. It has a solenoid in the front end to engage the gear. The starter is small and much lighter than the old Prestolites. The brushes are good for 2000 hours or more. It cranks really well. There are versions for Continentals.

http://www.skytecair.com/

The Lamar has had trouble with splitting drive gears. Had one do that. It was outside the SN range for affected starters listed in the SL but I emailed Lamar and asked for a replacement; never heard back. The starter had maybe 500 hours on it. Had a rather new Kelly fail, but can't remember exactly what went wrong with it. Might have been the front bronze bearing that chewed out. Magnaflites haven't been too bad, but they still have the old spiral-spline Bendix that sticks and needs cleaning and relubing with dry silicone spray. A pain. Skytec has them all beat.

Dan
 
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Dan Thomas said:
When an engine kicks back it can easily overload the drive far beyond what it was designed to take. Some of the new PM starters have a shear pin to save things if overload occurs.
Dan
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That doesn't say much for the guy who was caring for the engine, and checking the timing. the 0-200 has 2 impulse couplings, when timed correctly it can not kick back. because the impulse coupling main purpose is to retard timing to TDC before release.

kick back on any 0-200 is as rare as chicken lips.
 
Dan Thomas said:
I've bought several of these Skytecs in the last year or two:

NLLogowStarter.gif


I've tried Skytec, Lamar, Magnaflite and Kelly starters. This Skytec is the best by a wide margin. It doesn't rely on intertia to engage the gear or latches to keep it engaged or weak springs (that break) to retract the gear or spiral splines that sludge up and stick, and it has no front bronze shaft support bushing that gets dirty and wears out. It has a solenoid in the front end to engage the gear. The starter is small and much lighter than the old Prestolites. The brushes are good for 2000 hours or more. It cranks really well. There are versions for Continentals.

http://www.skytecair.com/

The Lamar has had trouble with splitting drive gears. Had one do that. It was outside the SN range for affected starters but I emailed Lamar and asked for a replacement; never heard back. The starter had maybe 500 hours on it. Had a rather new Kelly fail, but can't remember exactly what went wrong with it. Might have been the front bronze bearing that chewed out. Magnaflites haven't been too bad, but they still have the old spiral-spline Bendix that sticks and needs cleaning and relubing with dry silicone spray. A pain. Skytec has them all beat.

Dan
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that's a Lycoming starter, the OP has a 0-200 key start.

Lycoming is not the only engine being produced.
 
Really like Skytec myself, even on our O240 that keeps (maybe now kept?) poping drive shafts the two year warranty made them still a lower cost/hr than the OEM starter was.

Now I have a clutch type wating to go on when the shear pin style installed on there now pops.


And don't get me started on Lamar!!!
 
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