Starter pinion touching flywheel @ low rpm
- Thread starter J180B
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The previous owner's mechanic, 1500 miles away.
Daleandee
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Dale Andee
Ouch! I hate it when stuff like this happens. Regardless, it still needs to be addressed ...
What would the fix be, replace the whole starter unit? Or can that pinion's alignment be adjusted somehow?
Well first I'd have someone check to see if the new pinion is the correct P/N, if the pinion is installed correctly, and if the starter is installed correctly. Then plan from there.
Domenick
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Do not fly it like this. It will chew up your ring gear and pinion. $$$$
Depending on the aircraft ...
If this was my Cherokee, I would say the starter pinion (bendix drive) is not fully retracting. Likely gunked up.
When you hit the starter, the pinion is thrown into engagement with the ring gear. Once the engine starts and RPM overtakes the pinion RPM, the pinion is thrown back out of engagement. (The pinion shaft is an interesting thing with spiral groves).
Gunk will generally prevent the pinion from engagement and hitting the starter will produce nothing but a whine.
Less often, but still common, is the gunk preventing the pinion from retracting. This creates an alarming racket and the engine must be shut down instantly or damage will occur. It seems you issue is a partially gunked up pinion shaft.
Gunked up starter pinions can be cleaned after removal and disassembly of the starter, or it is possible to flood the appropriate locations with some solvent (brake cleaner) and dissolve and remove enough of the gunk to allow proper function.
Replacement bendix drives are available and not too expensive.
www.aircraftspruce.com
Depending on the aircraft ...
If this was my Cherokee, I would say the starter pinion (bendix drive) is not fully retracting. Likely gunked up.
When you hit the starter, the pinion is thrown into engagement with the ring gear. Once the engine starts and RPM overtakes the pinion RPM, the pinion is thrown back out of engagement. (The pinion shaft is an interesting thing with spiral groves).
Gunk will generally prevent the pinion from engagement and hitting the starter will produce nothing but a whine.
Less often, but still common, is the gunk preventing the pinion from retracting. This creates an alarming racket and the engine must be shut down instantly or damage will occur. It seems you issue is a partially gunked up pinion shaft.
Gunked up starter pinions can be cleaned after removal and disassembly of the starter, or it is possible to flood the appropriate locations with some solvent (brake cleaner) and dissolve and remove enough of the gunk to allow proper function.
Replacement bendix drives are available and not too expensive.
Pilot Supplies and Aircraft Parts | Aircraft Spruce
Aircraft Spruce is a worldwide distributor of certified and homebuilt aircraft supplies.
Dan Thomas
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There is a small spring that forces the starter drive back when it disengages. That spring sometimes breaks and you'll hear the flywheel ringing as the pinion gear touches it.
If someone has oiled that drive, there's another problem. Oil attracts dust, and when water gets into it, as it will, you get sticky sludge that inhibits the drive's engaging and disengaging. Usually, it just won't engage, just spin. The service manuals are clear on the lubrication: dry silicone spray ONLY. But too many mechanics don't read the manuals.
In your case I'd suspect the spring. The starter is engaging OK, and when the starter ceases cranking the flywheel will spin the pinion hard enough to retract it.
If someone has oiled that drive, there's another problem. Oil attracts dust, and when water gets into it, as it will, you get sticky sludge that inhibits the drive's engaging and disengaging. Usually, it just won't engage, just spin. The service manuals are clear on the lubrication: dry silicone spray ONLY. But too many mechanics don't read the manuals.
In your case I'd suspect the spring. The starter is engaging OK, and when the starter ceases cranking the flywheel will spin the pinion hard enough to retract it.
Do not fly it like this. It will chew up your ring gear and pinion. $$$$
Depending on the aircraft ...
If this was my Cherokee, I would say the starter pinion (bendix drive) is not fully retracting. Likely gunked up.
When you hit the starter, the pinion is thrown into engagement with the ring gear. Once the engine starts and RPM overtakes the pinion RPM, the pinion is thrown back out of engagement. (The pinion shaft is an interesting thing with spiral groves).
Gunk will generally prevent the pinion from engagement and hitting the starter will produce nothing but a whine.
Less often, but still common, is the gunk preventing the pinion from retracting. This creates an alarming racket and the engine must be shut down instantly or damage will occur. It seems you issue is a partially gunked up pinion shaft.
Gunked up starter pinions can be cleaned after removal and disassembly of the starter, or it is possible to flood the appropriate locations with some solvent (brake cleaner) and dissolve and remove enough of the gunk to allow proper function.
Replacement bendix drives are available and not too expensive.
Pilot Supplies and Aircraft Parts | Aircraft Spruce
Aircraft Spruce is a worldwide distributor of certified and homebuilt aircraft supplies.
Just to follow up. I had a conversation with the seller's mechanic. Said that this has been an issue for years and that it's caused by the fact that this is a rare narrow deck 0-360 and the tolerances just aren't the same. During prebuy, my mechanic noted some wear on the pinion, and it was replaced, causing this issue. Seller's mechanic said he tried different starters, which never got rid of the issue, but ultimately said it isn't a problem.
Perhaps it's rare on my model? PA28-180B.
Half Fast
Touchdown! Greaser!
Lycoming Wide Deck and Narrow Deck Engines | Resource Library
Information on identifying the difference between standard and wide deck configurations in the O-360 and IO-360 Lycoming engines.
resources.univair.com
Well if it were brought to me to fix, it wouldn't have flown till it was. The fact it did hit and your guy caught it, then you find it still hits, something is not right. Perhaps the ring gear is not true? But since it appears to be your problem now, you may want to actually get it fixed.
Salty
Touchdown! Greaser!
Mine had the wrong ring gear when I bought it. This doesn't sound quite the same. But mine had the wrong number of teeth which I didn't find out about until the starter pinion broke and we looked at it closer.
Daleandee
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I know absolutely nothing about this particular set up but shimming it came to mind when I first read this thread. Don't know if that's even an option here ...
Salty
Touchdown! Greaser!
count the teeth in the ring gear. If it's not 149 that's one of your problems. Probably not, but easy enough to verify.
To clarify:
The shimming involved depth of engagement of the gears.
Not fore- aft adjustment.
The “ Support” ( Lycoming name for aluminum portion of “ Flywheel”)
is only “ supposed” to install on the Crankshaft in one position.
This is accomplished via one thicker Crank / Bushing/Nut and a counterbore
in the Support. However; I have found several that were installed without
this alignment. At that point I walked away. Maybe if I was a masochist
I could have stuck around to determine whether the Support or the Crank
was damaged .
Perhaps a prior event of this sort?
The shimming involved depth of engagement of the gears.
Not fore- aft adjustment.
The “ Support” ( Lycoming name for aluminum portion of “ Flywheel”)
is only “ supposed” to install on the Crankshaft in one position.
This is accomplished via one thicker Crank / Bushing/Nut and a counterbore
in the Support. However; I have found several that were installed without
this alignment. At that point I walked away. Maybe if I was a masochist
I could have stuck around to determine whether the Support or the Crank
was damaged .
Perhaps a prior event of this sort?