IO-550 Starter Adapter and Starter Failure - Symptoms and Fix

[Ryan Riley]

Thought I'd pass along a common big bore Continental starter adapter failure. Certain years of the IO-520/550 shipped with Iskra starters coupled to starter adapters that have a smaller internal spring mechanism. This combo is good for only 400-450 hrs, and mine failed just shy of 450 hours. Here are the details for future reference:

Symptoms: starts that became slow/labored. The starter would engage, move the prop a blade or two, and then just spin without the prop moving. Mine would barely start the plane cold, and couldn't warm.

Fix: Called Niagra Air Parts and talked to Greg. I ordered their rebuilt adapter since they do a few smart tweaks to increase the internal strength.

Difficulty: Replacement is simple and straightforward. Pulling the starter is simple with no clearance issues. The adapter is mounted on studs and you have to slide it off them once the nuts are removed. I have the smooth faced starter adapter, so it cleared my firewall with about 1-2" to spare. If you have the model with an alternator mounted on it, it may not clear without moving the engine forward.

After I pulled the starter, I tested it and it was almost frozen and grinding with power on. Basically it also needed replacement. There are two main starters that have a good reputation and are recommended by Niagra. They are the Powerflite and Energizer.

[Admin]

Here are a few pics showing the difference between the lightweight Iskra starters TCM put on factory engines cira early 2000's versus a Hartzell Sky-Tec starter.

There's a big difference in weight and size. The Hartzell is much heavier. BTW, the Sky-Tec is one of two starters Niagara recommends.

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[Admin]

Did the swap and test procedure per Niagara's recommendation. The prop turns much quicker and the starter is quiet. Not a bad swap and I'm lucky I didn't have to move the engine to fit the adapter on the studs.

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[George Wehrung]

I tried the light weight Skytech but I went back to the older heavier hartzell as it actually spun the prop at 90 rpm. It draws more amperage but I think it does a better job.


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