Starter Issue

My new old airplane has an issue we can't quite figure out.

It sounds like the starter is engaging the starter ring wrong or something because it has a very loud (for the lack of adequate word) grinding noise and it seems to stay engaged longer than it should. We have cleaned the drive gear and sprayed with silicone, shimmed it away from the starter gear and nothing has fixed the problem. The engine is an aerosport and most of the parts including the flywheel are superior. I talked to Skytec/Hartzell and he sent me a Lycoming SL on how to shim but it is not the same type starter in the instructions. The model number is 149-12LS. Anybody else ever had this problem?

thanks

n38139 said:

My new old airplane has an issue we can't quite figure out.

It sounds like the starter is engaging the starter ring wrong or something because it has a very loud (for the lack of adequate word) grinding noise and it seems to stay engaged longer than it should. We have cleaned the drive gear and sprayed with silicone, shimmed it away from the starter gear and nothing has fixed the problem. The engine is an aerosport and most of the parts including the flywheel are superior. I talked to Skytec/Hartzell and he sent me a Lycoming SL on how to shim but it is not the same type starter in the instructions. The model number is 149-12LS. Anybody else ever had this problem?

thanks

Click to expand...

You are addressing the mechanical part, but have you checked to see if the solenoid release is lagging? You disconnect the starter motor electrical cable just activate the solenoid to (safely) see how the mechanical part works. You can check and ensure there is proper backlash that way too. If that is ok, then hook a wire to the starter motor cable so it will light up when the motor is engaged. Then you can see if it is electrical.

Follow Bill's advice on checking the solenoid and be sure to leave it engaged for a good 30 seconds while observing behavior. Your symptoms sound possibly like a weak or binding solenoid that is allowing the gear to drift backwards or not fully engage, allowing the edges of the gears grind as they try to hold engagement. Do you see any shiny bare metal on the aft edges of the ring gear teeth or the foreward edges of your starter gear teeth?

Thanks for the input. One of the things that is obvious after looking again is that starter ring looks as though the back side is chaffed however the gear on the starter looks like it is engaging properly based on the wear pattern on the teeth. I looked and it is a 149 tooth ring gear. As soon as the starter is engaged, it makes the noise and continues until the gear disengages from the starter ring.

So is this an issue with a new plane you acquired or something that just started happening to your plane? If the former, you want to look at the possibility that the starter is too close to the ring gear in the for/aft plane, not the center to center alignment. Some Skytech models have a very tight tolerance for the fore/aft clearance with the ring gear. I thought is was the NL model, not the LS. Lyc/Superior make two or three different styles of ring gears and the wrong ones are often installed. When this happens, the face of the bendix drive (the flat face just aft of the gear teeth) will hit the ring gear due to reduced clearance. This would explain the wear you mentioned and would likely make an unpleasant sound while spinning. Skytech has a document discussing this subject in detail on their website. I suggest you read it.

Also, the LS is known for cracked housings. Do a close inspection of the forward (bullet shaped) housing and the forward shaft carrier with the bushing.

Larry

I have no practical experience of this problem but I seem to recall that there are different starter gears for different ring gears. You have 149 teeth, can you check that your starter is correct for that number of teeth.

Check your starter to determine if the mount is bent. Mine acted like that and it was bent, but you can't really see that it's bent - you need to measure it.

Thanks for all the inputs.