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Article on propeller maintenance

From the US AOPA online

What I wonder about is this

While we’re on the subject of tow bars, make a habit of never leaving a tow bar attached to an airplane when it’s not being used. Tow bars and propellers seem to battle it out routinely, and I have yet to see a propeller leave the fight as the victor. This leads us to another note: If a propeller hits a tow bar and nobody except the pilot sees it, it still gets damaged. Don’t assume you can give it a quick once-over and continue your planned flight. The propeller needs to be carefully inspected by a mechanic and have a dye penetrant inspection of any suspect areas. Depending on the situation, it may even be cause for opening up and inspecting the engine itself.

I would think that any contact between a running prop and a towbar - that results in any prop damage other that trivial leading edge dressing - needs a shock load inspection.

Typical towbar-prop contacts tend to take out at least a square inch (say 30x30mm) out of the prop and I cannot imagine not doing a shock load inspection after something like that.

Administrator
Shoreham EGKA, United Kingdom

What if you hit the tow bar while cranking?

I have to admit I started the engine on the TB10 with the tow bar attached. Luckily the tow bar is well designed and there is a 30cm clearance between prop and tow bar. I noticed before taxiing...

I think you mean 30mm

I have a similar clearance on mine. But that just means one could take off with it quite easily.

What if you hit the tow bar while cranking?

You can still damage the mags.

Administrator
Shoreham EGKA, United Kingdom

The clearance between prop and tow bar on "my" TB10 is very large, 25-30cm. Luckily in Germany there is a requirement to have AFIS whose job is to check for tow bars on takeoff and landing gear on short final!

I'd like to see a photo of your towbar in place. I wonder where it is attached? Is your towbar straight?

Your prop can't be that much smaller than mine in diameter, yet mine only just misses the towbar.

Administrator
Shoreham EGKA, United Kingdom

Another good article on props is here. It’s a quick and easy check.

However, if it fails, you may have a lot of work to do. And if it passes?

I recommended this years ago to someone with a homebuilt who got a gear-up in a hangar, smashing a composite prop. Someone apparently disabled the squat switches and raised the gear. Obviously the check would have been done after fitting a new prop, to check the crankshaft flange runout. No idea what the outcome was.

Administrator
Shoreham EGKA, United Kingdom

achimha wrote:

Luckily in Germany there is a requirement to have AFIS whose job is to check for tow bars on takeoff and landing gear on short final!

Really? I thought the AFIS was there solely due to fire regulations – if something happens, there is someone to call the fire brigade. From experience, I know most of my the local flugleiter spend most of the time in the tower watching TV, chatting with others or drinking – checking whether a plane has it’s gear down on landing or tow bar on departure is not considered part of their remit and having seen a particular plane take off / land a couple of thousand times leads to a certain loss of interest in watching said task happen again…..

Or did you miss a from your comment?

The next instalment of the US AOPA article is here.

Administrator
Shoreham EGKA, United Kingdom
8 Posts
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