Cessna 172SP starter pinion

[miroc]

Last Saturday I wanted to start my engine on Cessna 172SP the starter pinion did not jump out. I can hear the starter motor spinning but that's all. I did some telephone calls and the advice was to spray the bearing with silicone spray first. I will try this but not sure that can help. The machine was born 2006, maintenance is good, ARC is 3 weeks old, 4 hours flown since check. The starter is (probably) Lamar PM2401. The question is what if the silicone will not help?

New starter? Which one?

Lamar? Lot of negative opinions found on Internet.
Prestolite, Hartzell (Kelly), Sky-Tec?

New or overhauled one?

Any opinions?

[Pilot DAR]

Lubricant in the pinion area of the starter will probably help, and will do no harm, even if it does not have the desired effect.

If not, have the starter removed, and rebuilt by a qualified organization. Starters are very rebuildable, and parts are generally easily obtained.

If you need to replace the starter, I can say that I have a good opinion of Skytech, but that is not a negative statement with respect to the others.

[Halfbaked_Boy]

Does the 172 have a starter bendix?

Had this problem on an Arrow. Flew it to maintenance base (after using a screwdriver to force it to engage), new bendix installed, flew out again in half an hour.

Apologies if this is of no relevance to a Cessna, have done no research.

:)

[Pilot DAR]

The later 172's and all Piper Cherokee/Arrows, have Lycomings installed, and all Lycomings use an external starter and ring gear arrangement. Bendix can be sticky, usually an easy fix...

[IO540]

Skytec lightweight starters are good.

But go for the later "lower current" versions as the original ones drew masses of current - the very nice and fast engine cranking does not come free :)

Get a new one; they don't cost that much.

[Aerials]

Not sure if my short tale will help. I had a car once where the starter motor whizzed round but didn't turn the engine. Fault turned out to be oxidation on battery terminals. Big current draw = volts drop = not enough volts left at the starter motor to make it go a bit quicker! Check all associated heavy current cable terminals. If you can, have the battery checked for condition (where the battery is subject to a heavy load and the terminal voltage measured to see if it is within acceptable limits). It may just be that your battery is beginning to sulphate? - give up.

[miroc]

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Fault turned out to be oxidation on battery terminals. Big current draw = volts drop = not enough volts left at the starter motor to make it go a bit quicker! Check all associated heavy current cable terminals.
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External power did not help. This was the very first action taken. This closes out the battery.

Wiring is good, ARC was made middle of October in a good shop in Germany. Since ARC renewal I started at least 4-5 times successfully.

The diagnose is IMHO some kind of mechanical failure at the starter. Solenoid, bendix...

If the wizardry with silicone spray will not help, I have to pull the starter out and have it overhauled or buy a new one. If this will be the case, I have couple of options regarding the producer. Looking for advice.

[miroc]

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Skytec lightweight starters are good.

But go for the later "lower current" versions as the original ones drew masses of current - the very nice and fast engine cranking does not come free http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

Get a new one; they don't cost that much.
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After looking at different company-websites my favourite one is Hartzell E-Drive. SkyTec is the second one.

I am not so sure regarding the new/overhaul option. By my personal experience (not in aviation) the overhauled can be sometimes better than the new. I do not know why it is going this way, maybe during the overhaul process there is better quality control and more experienced staff involved.

[Katamarino]

I had this problem on an SP in the USA. Landed, taxied to fuel, shut down. Once refueled, the starter just whizzed round and she would not start! It turned out to be a stuck Bendix, which the mechanic engaged with a screwdriver for us to fly on to Grand Canyon where the rental comapny had overnighted a new starter, and it was swapped out while we toured the canyon :cool:

[miroc]

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and it was swapped out while we toured the canyon
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There are no canyons long enough in Europe to get something swapped on an airplane during the canyon-touring! :O

[Big Pistons Forever]

This is why every pilot should be taught how to hand prop an aircraft.....

[Halfbaked_Boy]

This is why every pilot should be taught how to hand prop an aircraft.....

I agree...

Following the snowfall the UK experienced last Winter, I came back to the Cessna 150 I was leasing to find the battery flat as a pancake. Engineering was shut for the weekend, and to be honest, for the sake of a battery that just needed some more juice, a handswing seemed in order. I must have asked ten people (mixture of pilots/ground staff), who all replied that not only were they not able to swing, but would also feel uncomfortable 'covering the controls' while I swung it!

For a period of about half a second, the thought even crossed my mind of setting the brakes, the mags and the mixture and swinging it completely alone. Of course this lasted for only the briefest of moments, as all manner of nasty endings flashed through my mind...

Can be very frustrating sometimes, this flying lark! ;)

[NutLoose]

Would agree with what said, if the lube does not free it with the battery off and a screwdriver push the bendix round a bit to see if it will turn or tapping the bendix housing with a soft headed hammer...... (do not beat the life out of it when tapping it) may free it off, failing that it may be the pin has gone between the bendix and the starter. silicon can sometimes actually make things worse when lubing and I have used rarely a little bit of WD40 to free them off beore re applying the silicon spray.

[Pilot DAR]

This is why every pilot should be taught how to hand prop an aircraft.....


I disagree. Aside from being an element of type familiarization for those older aircraft which never had a starter installed, pilots should only plan to operate the aircraft using the systems designed into it. Firstly, and simply, with an inoperative starter, or flat battery, the aircraft is not airworthy. We're not planning to fly unairworthy aircraft, right?

I have hand propped many aircraft, and cringe every time. A Cessna 180 floatplane I test flew two days ago, had a flat battery. The maintainer tried to hand prop it (I know it can be done - i've done it). This was not going to work, and his being dunked in a cold lake was probable. We went for a nive coffee, while the battery charged... everything worked just fine after that....

Hand propping will not work on a Lycoming where the attempts to start have failed because of a discharged battery.

Too many things do go wrong with hand propping. A few pilots must know how to do it (though many seem to wish for starters), the rest should assure that they operate the aircraft as it was designed, or have maintenance preformed as required. It sounds harsh, but I have witnessed too many hand propping accidents - in cluding my own minor one, decades ago

[Halfbaked_Boy]

We're not planning to fly unairworthy aircraft, right?

Of course not - but once that engine's turning, the battery is charging, and handswinging to a start gives you the opportunity to ground run it to a point where you can switch off, and check to see if the battery has recharged. If not, then it implies a deeper problem than simple drain, and as such should go to maintenance. If so, however, then the aeroplane is back in airworthy condition and ready for flight (following standard start).

Hand propping will not work on a Lycoming where the attempts to start have failed because of a discharged battery.

I know next to nothing about engines or indeed batteries, but my particular scenarios have all involved Lycomings, and ultimately I've had them running again following handstarts. This from a point of battery discharge that produces absolutely no response whatsoever when turning the key to 'start'. No ticking, no nothing. Although I appreciate this doesn't necessarily mean it is completely discharged, and of course the battery needs a small charge to at least enable the engine to run. :ok:

Too many things do go wrong with hand propping.

Indeed - I wasn't having a go at the fact nobody was willing to help me out, and I'd never attempt to 'teach' somebody how to do it or become their own test pilot. It was just eyeopening to see the amount of people who simply couldn't do it!

There's a lot of gaps in my understanding of these things, but that's been my experience to date. :)

edited to add - I should mention, my experience (confidence?) with handswinging is limited to giving the muscle for many a start on the Moth :ok:

[Big Pistons Forever]

I disagree. Aside from being an element of type familiarization for those older aircraft which never had a starter installed, pilots should only plan to operate the aircraft using the systems designed into it. Firstly, and simply, with an inoperative starter, or flat battery, the aircraft is not airworthy. We're not planning to fly unairworthy aircraft, right?

In the example provided by the original poster all the aircraft systems are perfectly servicable except the starter won't engage. After the engine is started by hand swinging the aircraft will be in exactly the same state as if it were started with the starter, that is engine running with the starter bendix stowed....so how is the aircraft unairworthy ?


I teach all my CPL students how to safely handprop a light aircraft so they have the option if ciucumstances dictate that hand propping would be the best course of action for the circumstances of the situation. I will teach PPL's if they ask.

Hand propping is a skill which can be taught. Done with correct preparation and slowly and methodically carried out, I think it is perfectly safe.

BTW from a practical point of view, my students feed back has been the most valuable tip, is how to deal with a weak battery. That is the starter turns the prop untill it hits the first compression and then stops. I show them how to load the cylinders with prime and then position the prop just after a compression. When the starter is engaged the prop will then usually have enough momemtum to bump over the next compression and with the engine allready primed it will usual fire at this point. Of course I emphasize the dangers of moving the prop particualarly with a primed engine, This method has been successfully used by several of my Ex students to avoided a stranding away from their home field.

[Pilot DAR]

I can only mount a weak argument against promoting handpropping as a "normal" practice in case of difficulty in today's aviation. There are some things we just "don't do any more". Perhaps the example of actually shutting down an engine in flight on a twin for single engine training. I was trained that way, but it was not long after that this practice was deemed inappropriate for training. Like that, I hold the opinion that the risk to benefit ratio for hand propping is poor. If your plane won't start, there are appropriate resolutions which do not involve hand propping. When I fly the amphibian to a remote place, I always carry a charged jumper battery, and a car solar charger which would charge it, under the right conditions. I've never needed it. I have flown batteries and starter motors into remote lakes in the past, for other unfortnunate pilots.

I know it's a double standard, because, yes, I would hand prop my 150, under the right conditions. But I don't think I'd train it, other than for the new owner of an aircraft which by design, could not be started any other way.

As for starting a Lycoming, which has suffered a discharged battery during start attempts (and I do understand this was not the scenrio originally presented), in many cases it is not possible, because many starter motors will have the bendix pinion now engaged with the ring gear, and only a running engine seems to disengage it. So to attempt a hand porp start does not work, because you're turning over part of the starter motor drive train, at a very unfavourable ratio.

An engine in a plane, which cannot be started by it's designed means is probably in need of some form of maintenance type action. It is my opinion, that pilots are best trained to recognize, and seek out this maintenance.

[miroc]

Yesterday I sprayed the Bendix with silicone spray. I started four times and the starter worked fine every time.

Solution of the problem was proper lubrication of the moving parts.

[Pilot DAR]

Happily, there are a few things in aviation, which are much more simple than they appear!