As for the engine and prop, how best would you flush them out?
Why the prop? Oil doesn’t circulate through the prop, does it?
Why the prop? Oil doesn’t circulate through the prop, does it?
It does. The propeller is operated hydraulically with the same oil that runs through the rest of the engine.
Yes but the oil doesn’t flow through the propeller, it’s always the same oil operating it (minus a bit of mixing at the boundary layer).
Oil enters and leaves the propeller during pitch changes. It does not cycle all the oil, but depending how many prop cycles, it can circulate enough. More importantly, the propeller is spinning (yeah, I know that you knew that) so the centrifugal force is spinning the metal in the oil to the outer walls of the prop hub, where it will load up. Any inside cylinder with oil in it will separate out the metal when it is spun. This is the heart of why the key start clutches in the O-200’s were so troublesome – the clutch worked fine, if it was clean. But fill it with metal slime, and proper operation was impossible. Unfortunately, Continental did very little to enable cleaning.
Back in the day, an IO-520 came in to our engine shop (affiliated with the starter shop) which had made metal. Our staff fully overhauled it. It went back, was installed on the 185, and went flying. It was not long before there was metal in the engine oil again, The prop had been re n re’d, without cleaning, and served as a rather large repository for harmful metal, which found its way back into the newly overhauled engine. That engine was soon back for a teardown, with I think tens of hours on it since overhaul. Cleaning out a constant speed prop, or other accessory containing engine oil, is never a bad idea….
We learned many things about these systems. Certain starter adapters were prone to breaking the shaft gear. This could result in an engine failure shortly afterward in certain engines, but at least lots of metal in the engine, and flailing gears. There was an AD against all of these engines to replace a rather expensive shaft gear. What I found was the starter adapters containing these shafts was being bench assembled, with the shaft carried in two ball bearings in the bolt together adapter housing. This seemed fine, but the assemblers often forgot that the exposed end of the shaft gear also ran in a bearing, but that one was in the engine case. This made for three support points which must be aligned. So, if the alignment of the two adapter housing pieces was not perfect, the shaft would not be perpendicular to the mounting face of the adapter/engine. So, the adapter would mount to the engine, but when it was tightened down on its studs, in could preload the shaft gear in bending. Bink goes the shaft one fine day, and you have a rather serious problem. Once I realized the problem, I had a fixture cast, and machined it with the bores, so it could be used to assure everything was aligned before assembly to the engine – never a problem with our adapters! Favoured shop customers go one of our fixtures…..
There is about as much to know about Continental adapters, as there is about the rest of the engine.
How easy is it to fit a starter engaged light or is it a job for an avionics shop?
Very easy. Get a nice light, suitable avionics cable and connect it to starter solenoid. Put an inline fuse close to the solenoid.
Of course the ‘starter engaged’ light only tells you that there is power going to the starter but doesn’t mean that it is disengaged when the light goes out – this is no longer a UK requirement.
Indeed – how could you tell the starter is disengaged (short of installing a switch or a proximity sensor facing the end of the shaft)? All that a starter warning light would give you is that the starter switch or the starter solenoid have failed in the ON position.
I can imagine detecting a stuck starter from
OR
With the second option I am assuming that the back EMF from an engine-driven (stuck-engaged) starter is going to be a lot more than 12 or 28 volts. One could measure this by spinning up a starter on a bench with an electric drill. In fact just a 12V relay coil across the starter relay (with a diode in series) might alone work, with the relay contact operating the panel lamp. But if the motor generates say 200V then a 12V coil would pretty quickly burn out, so one would need to do some measurements at a real simulated engine idle RPM to select the right coil voltage, and then test the chosen relay at cruise RPM to make sure it doesn’t get too hot.
Doesn’t a stuck starter motor play havoc with the aircraft bus(es) by lifting up their voltage?
To me, the starter engaged light is useful but only part of the solution. It would be really useful to know that the adaptor spring has relaxed away from the shaft completely into its design resting position. After all, it’s only this position which stops the starter adaptor making metal.
The new type of adaptor relies on the adaptor spring being in contact with the shaft at all times, why would you design it like that, it’s a metal making machine surely. At least the classic adaptor operates with a clearance between the spring and shaft which must be better.
I’m following PilotDAR’s advice and that of Niagara Airparts to install the classic type of adaptor with the original heavyweight starter at least for now. I have tested the heavyweight starter on the bench and it takes only 2"-lbs to turn the shaft so that’s way below the limit of 5"-lbs required for reliable operation.
I’m more than ever convinced the lead up to my starter adaptor failure is this:
1). At about 60 hours the starter switch became defective where if you turned the key hard it went beyond the start position and lost contact momentarily. This cannot have done the adaptor any good.
2). At around 80 hours the engine backfired and on subsequent start the spring had not disengaged fully causing a whine. At the time I had no idea where this whine came from. My mistake. I should have shut down and tried again.
3). By now the adaptor was patently damaged unknown to me. I fitted an M type Hartzell starter being persuaded by the advert that this was the only starter which is not damaged by a backfire. Now I’m not sure if my adaptor was even compatible with this starter.
4). The oil analysis always showed high iron, I thought it was from the cam follower problem and subsequent run in for the second time. Now I know it’s likely to be from the adaptor eating itself.
5). To help with the cam follower issue I went from 15W50 to W100 plus Camguard. The engine was definitely harder to turn over when cold. More stress on the adaptor.
6). Over the winter the engine was turning over slower and slower. I was blaming the battery and the W100 which was changed to W80 in the coldest months. Now I know it was the starter adaptor.
7). Then failure at Oban.
Steep learning curve for me.
The starter engaged light is only a part of the solution to the problem, but for such a very simple installation, it is a major part of the solution for big Continentals. Lesser to the small Continentals and Lycomings, but how can it hurt? Yes, a fused light powered off the starter contactor. If the contactor remains closed following the release of the key, shut everything down and investigate. That, coupled with a free turning starter motor, and a classic style adpater which started out in good condition is about 98% of the solution to all big Continental starter problems. This is not a difficult solution to such a big and expensive problem.
The new starter motor I am testing for Canadian Aero/Niagara Air Parts is a small, light permanent magnet geared motor, but with the addition of an ingenious system inside, which I will not describe on a forum, which assures that there is zero possibility of drag on the starter adapter following de-energizing the motor. In the very unlikely event of a failure of this motor, it will not turn the adapter at all, so fails safe. I am so satisfied that this is a good idea, I am testing it on my friend’s brand new 550 in the 182. So far, perfect, and you can be assured I am paying close attention. I will report more on this as I progress. This new starter motor will be available for sale in the future.
My test engine is also equipped with an MT three blade reversing propeller, which I am also approving. I am endlessly pleased with this propeller, though conscious that it has a lesser polar moment of inertia, so a kickback is more possible. The big two blade metal props have a large flywheel effect, which tends to defeat kickbacks by keeping the engine turning forward. The lighter props not so much. That said,with a properly timed, well maintained engine, I have never had a problem with this installation.
It sounds like STOLman is really understanding all of the factors here, and that is the very best thing for keeping the high reliability to low operating cost ratio we all want…
