My aircraft has a Continental IO550 engine. To start the engine you operate the starter which turns a worm gear which tightens a spring onto a drum, turning the drum which via gears starts the engine. This is the starter adaptor mounted on the back of the engine.
To be honest I never really understood how this thing worked but I do now. There i was with my wife sitting on Friday evening in the plane on the apron at Oban Airport hoping to fly to Newcastle to look after our Grandchildren. A normal flight you could say, did all the pre-flights, primed the engine, turned the key and watched the prop move. It turned through 90 degree then backfired and spun backwards 120 degrees. Only once before had I encountered such a backfire a year or so previously. Did I over prime, maybe a bit. The engine had been stood maybe 5 hours so to me it was a normal cold start. I turned the key again and all I got was a whirring sound. Tried again, same. Oh no, I immediately knew the plane was not going anywhere.
At this point, my mind racing, how do we get home from Western Scotland, who is going to look after the Grandchildren, what has gone wrong, no Hangarage available, no engineering support, exposed site, now what. My wife looking at me with that look of, well, get it going. “We ain’t going anywhere” I said so then her mind starts whirring.
I beckoned the passing fireman and told him the plane was not going anywhere. He suggested I find Donald, he is building an LSA in the only little hangar. Donald lent me some tools so I removed the cowl and removed the starter. The starter removal was at the suggesting of my IA who by now I’d spoken to on a flakey phone line. He said, the woodruff key in the starter motor may have sheared.
In the mental overload of this first hour both the IA an I had forgotten that we fitted some two years earlier a new Hartzell (Kelly) M type starter designed solely for use with the starter adaptor. Kelly had designed out the woodruff key by inserting a bevel toothed clutch arrangement which drives in one direction but in the case of a backfire freely spins in reverse so no damage can be done. Anyway, I took it off, put it in Donald’s vice and tested it. Perfect. It must be the starter adaptor. Shall we take it off says Donald. Can we get it off?
Also, by now a TB20 had landed with a couple I know well. They came over to help. We discussed hand propping the engine but decided against it, an IO550 is a big lump. Days later I’ve been given the hand propping technique which of itself is really interesting, you don’t have to Spin the prop hard at all. However, we decided that it would not be safe to attempt a hand prop but furthermore we did not know what was broken and starting the engine might not be a good idea.
Spoke again to my IA, could I attempt to take the starter adaptor off and have a look. He said, you don’t know what you are taking on. It’s likely you will have to move the engine forward to get the unit off due to lack of space between the firewall and the engine. Now we realise the plane is stranded and the only way to get home is with our son who was competing in a motorcycle trial at Kinlochleven, the reason we were there in the first place. After the event he drove us back to his home in Newcastle, then next day we flew commercially home.
Before we left the plane at Oban we secured it as best we could. Donald and the firemen could not have been more helpful and I felt quite comfortable at leaving the plane, not that I had any choice.
Yesterday, I ordered a new starter adaptor from the US. Now I wait. My IA is set to accompany me back to Oban with enough equipment to do the job just the moment I get the new adaptor in my hand. Good old Donald has borrowed an engine lift locally so we don’t have to lug one of those up to Oban.
Doing the job will be a challenge in the open, it may be possible to get the nose of the plane into the little hangar, I do hope so. It’s 95% certain to be the starter adaptor that has failed. If the internal gear is damaged then it is engine out completely, not just moved forward a few inches.
There was a lead up to this supposed and not yet confirmed failure of the starter adaptor. Some time previously, as I mentioned above, the engine backfired but then started normally on the next turn of the key. But…. There was a low pitched whine in the engine. I should have shut the engine down immediately but did not and flew to Carlisle, 30 minute flight. The barely discernible whine was heard all the way. After the restart in Carlisle there was no whine and I forgot about it. Now I know what happened, the backfire had done something to the starter adaptor so the spring could not relax fully and was interfering with the drum, hence the whine. Obviously, the 30 minute flight has done the starter adaptor spring and drum arrangement no good at all.
Shortly after this is when the Hartzell M type starter was fitted thinking I don’t want to be stranded with a sheared woodruff key even though a spare was in the plane now.
The oil analysis was showing some problems with my engine from the start. It turned out to have the bad batch of followers which were spalling and other issues with compressions. Continental refurbished all 6 cylinders and gave me a new set of followers all under warranty. I ran the engine in again but the oil analysis still shows high iron. It’s very likely the iron is coming from the starter adaptor, from the spring grinding on the drum. Time will tell.
After the warranty work the engine settled down nicely apart from the constant high iron which was baffling, but now it’s possible we have found it.
Over this winter the engine has been harder to start especially when hot. I put it down to running heavier oil W100 plus Camguard, under the advice of my IA to help keep cam wear to a minimum. The plane lives in a heated hangar so W100 was used throughout the winter. This put extra strain on the starter adaptor. The engine in these last few flights has turned over slower and slower. I blamed the battery and was just about to buy a new one. Looking at various forums (that’s the brilliant thing about these forums) there was plenty of evidence of starter adaptors failing which a slower turning engine being a symptom. Interesting, plenty of evidence that high iron in the oil analysis was also reported prior to the starter adaptor failure.
So, I’m only half way through this story. Fitting the new starter adaptor at Oban is going to be challenging. And….we don’t know if this will fix it for certain. Fortunately, my pilot pals have rallied and I’ve loads of offers of being flown up to Oban but I fear I’ll have to drive up with my IA and all the gear. I’ll report on the next bit of my sorry tale when it’s done.
I’m sorry to hear of your problem: I’m convinced aircraft know when they are at the most inconvenient possible location and the worst possible time in the most awful weather and then break themselves deliberately! 
I hope that this may be of some help although you don’t say what starter adapter you have nor what aircraft type.
The Continental 550 is fitted to the Cirrus SR 22 and the original Iskra starter adapters fitted to them have an awful reputation on COPA. Mine failed in much the same way on a cold dark night at Prestwick although I was lucky enough to get one last start out of it and got home OK.
Most people seem to have replaced the original starter / adapter with a Sky Tec or TCM which seem to be much more reliable. There is quite a lot of information on this on COPA and, if it would be helpful, I will ask the original posters there for permission to cross post here.
For any COPA members interested, here is a link to a thread covering this.
[URL fixed]
I don’t know anything about this, but is this the scenario where both the starter and the alternator are bolted to the engine in a “sealed” manner, with the alternator being gear driven rather than belt driven as they tend to be on Lycos?
What I have read is that with these engines, any failure of these accessories ought to be presumed to fill the engine with metal fragments.
Yes, that is a standard problem with Continentals and all the symptoms match. Note that it can also destroy your engine when it starts eating teeth of the gear. High iron on a Continental is a clear indicator of starter adapter problems.
Make sure to analyze the situation thoroughly and take the right measures. I have heard from too many occasions where the same thing would happen only hours after installing a new starter adapter. It’s a very bad design. Mag timing should be checked as well.
Here’s some background on the starter adapter: http://www.csobeech.com/adapter-mystery.html
If the prop was turning freely, I would probably have handpropped the plane. IO550 or not, doesn’t make a big difference. There was a time when all airplanes were handpropped…
My plane is a STOL converted Cessna 182 called a Katmai. There are only a handful of Katmai’s in Europe, one in London and one in Switzerland. The IO55o is fitted as part of the Katmai spec. Apparently whether it’s the standard O470 engine or any variant the starter adaptor is a pig to remove because then engine needs to be moved forward 100mm or so to get the shaft out.
At one point there were 4 pilots around my plane. We discussed at length hand propping the engine but decided it would not be a good idea because nobody knows what is broken and it’s so easy to do more damage. Todd Peterson who builds the Katmai sent me this hand prop procedure. It’s interesting:
There’s no way I would replace the starter adaptor in the field if I could fly it home for the work. I have hand propped these engines before and it is really very easy but one has to be very careful. Here’s the procedure. Park brake on with the pilot also holding the brakes with his feet. Master on, mixture rich, throttle in a little just like a normal start then turn the boost pump on for a few seconds to prime the engine. With the ignition switch off carefully pull the prop through one blade at a time. Do not really grab the prop hard with your fingers have just enough grab to get it through compression. When the prop goes through compression let go of the prop. You do not have to really swing the prop hard rather just pull the blade through compression and let it go. Run eight to ten blades through this way and it will get the engine primed. Once you pull the prop around so the blade is coming up on compression have the pilot turn on the master and go hot with the mags. Pull the prop through until you hear the impulse couplings snap and let go. You do not need to swing the prop hard to get it started. Merely pulling the prop through will do the job. If the engine does not start have the pilot switch the mags off and reposition to blades to give you another go at it. Do not reposition the prop for another try with the mags hot. Then go hot with the mags and pull the prop through compression again. If you go through a number of blades then have the pilot give the engine another little shot of prime and keep at it. Normally the engine starts pretty straight away doing this. Just remember you do not have to swing the prop hard. Just pull it through compression until the impulse snaps, let go and back up. I’ve started tons of various aerobatic engines this way and it works well.
Todd agreed eventually it was too risky to run the engine until the source of the breakdown is known for certain.
Still waiting for the new part.
What was the iron figure in the oil analysis, STOLman?
Here are the last few iron readings:
110/116/97/147/101/67/95
The 147 coincides with the 30 minute flight I did with the whine.
If that is in PPM that is outrageously high and I would be sending my engine off for a rebuild, immediately.
I would be sending my engine off for a rebuild, immediately.
Not unless it has swallowed parts of the gear. This is a normal sign of Continental starter adapter issues. You don’t have to do anything about the engine unless you do not know where the metal comes from or the engine is chewing on bigger parts.
What the bad exhaust valve design is to Lycoming customers, the starter adapter is to Continental customers — crap design!
Off topic, but Lyco fixed the valve issue with different cylinders, many years ago.
STOLman – what does your oil filter look like?
