Nose-over rebuilds ?

[BobK]

Hello,

While not really a 170 question, I was wondering what the concensus was towards rebuilds after putting an airplane on its nose during a ground-loop. Are teardowns absolutley necessary regardless of the engine, or does that have anything to do to it ?

For example... If a Cessna 140 was looped and put on its nose during landing, would a teardown of the C-85 engine be required ? Im looking at one for sale, and that is the fly in the soup that is making the deal feel sour to me. The prop was replaced, and the nose bowl straightened, and it has about 30 hours on the engine since this incident. No engine teardown was done, but apparently the crank flange was checked. I havent seen the logs for the plane yet.

I really dont feel good about it, but I wanted to see what others with experience had to say about it.

Thanks again !

Bob K.
Anchorage, AK

[Iceman07]

I thought, but I really don't know, that any prop-strike requires at least a complete tear-down and inspection.

There are a lot more qualified people that will answer your question, however.

[Bruce Fenstermacher]

Continental says that any damage to the prop that requires the prop to be removed to be repaired REQUIRES a tear down inspection.

Of course in the old days this wasn't the case so many disregard the advice. I didn't when I had the most minor of a prop strike. So minor I had to show the insurance inspector the prop damage. Essentially one blade took less that a normal golf divot from the ground as the engine came to a stop. I never regretted having it looked at.

My Cub C-85 is currently disassembled for bad bearings and crank which is another story. Since the crank was being checked I also asked to have the flange looked at closely. Turns our the flange was out of spec probably fro a strike and the crank should not have been yellow tagged. This explains an annoying vibration the engine seemed to have.

If it where me I'd steer clear unless the price was very very very very good. Then I'd have the engine torn down and crank inspected. Cranks for C-85 when you can find them run from $700 to $1600 for tapered shaft examples. Flange examples which you'd be looking for are more. An STC is available to put an 0-200 crank in a C-85. The STC, new crank, pistons and rods cost $2620 plus maybe case modifications. And at that point your are probably realistically talking a total major overhaul.

[davevramp]

Bruce is right. You should read the Continental requirements for your self to understand were Continental is coming from. It is not the crank that is the weak link. A teardown requires a NDE of the gears in the accessory case, a long with complete inspection of all internal parts. Sudden stop on the gears may induce stress points that would fail in flight at a later time. It is not cheap and not all sudden stoppage completes the inspection as required. Dangerous stuff.

[sphillips]

See Teledyne Continental SB96-11a on there website.[/url]

[lowNslow]

See Teledyne Continental SB96-11a on there website.[/url]

http://www.tcmlink.com/pdf2/SB96-11A.pdf

[GAHorn]

This link was provided in our own MX Library section as well.

http://cessna170.org/phpBB2/viewtopic.php?t=1913

In essence, "mic-ing" the crankshaft flange is worthless/useless. If the engine was stopped by the prop such that the prop had to be removed to repair it's damage...then the engine and all rotating accys' must be torn-down and inspected. (If this wasn't the case, ....then ask the seller why he doesn't simply repair the airplane and keep it?)

Many times owners will make the insurance claim for the damages (including a settlement for teardown) and then not perform the work but simply sell it. If you can determine that is the case, you might be in a better bargaining position with the seller. (He's already re-couped some of his money.) But don't buy this engine without plans to completely tear it down and inspect in accordance with the TCM mandatory Service Bulletin linked above.

[BobK]

Thanks Gentlemen !

I had a feeling that was the case, and even though Ive heard of people ignoring the teardown requirement, it just didnt feel right. Im sure this guy didnt just collect the insurance money and run. He was adamant that insurance was a waste of time, along with being critical of all the A&P mechanics just trying to pad their wallets by requiring teardowns that werent necessary...

When I asked what the compressions were on the engine at the last annual, he told me that compression numbers didnt mean anything, so they didnt need them. He said that his 72 year old mechanic can pull the engine thru by the prop, and listen to the exhaust for compression, and tell that all is well... He also refused any kind of test-flight without a non-refundable deposit, and kind of shrugged why I would need a pre-buy. Yeah... Like I said I didnt get a warm and fuzzy feeling about things.

I dont plan on purchasing this airplane at this point. It was a beautiful plane for a decent price, but with things like this, I can see why its been for sale for over 8 months. Thank you again to everyone for your invaluable advice ! The search continues...

Hasta ~

Bob K.
Anchorage, AK

[mit]

We aren't doing ourselves any favors by using the word mandatory in the regulatory sense. The service bulletin is not mandatory by the FAA part 91. The Lycoming one is since it is an AD. Hundreds of engine's have been run after prop strikes past TBO. Before we became more litigious.

[Bruce Fenstermacher]

Tim you are right. Only Continental (I haven't reviewed Lycoming policy) says it's mandatory. And you are also right that many prop strikes have happened in the old days that tear down inspections where not completed and the engines where fine.

The only prop strike that I might be able to let slide is one that I personally witnessed so that I could, with first hand knowledge, determine for my own piece of mind that engine damage was unlikely.

This was the case with my Cub engine. I don't think you could have a less severe prop strike. I thought about it over and over in my mind what to do. All I could think about is I'd never enjoy flying the plane again till I knew for sure there was no problems lurking inside.

Thoughts of how well the Cub would fly missing a prop as the crank severs and the prop departs the aircraft as I've seen happen to others was just to overwhelming.

[GAHorn]

We aren't doing ourselves any favors by using the word mandatory in the regulatory sense. The service bulletin is not mandatory by the FAA part 91. The Lycoming one is since it is an AD. Hundreds of engine's have been run after prop strikes past TBO. Before we became more litigious.

"Mandatory" is the mfr's determination for use in commercial service and for engines still in warranty. It's a good word. I consider the service bulletins mandatory. I carry insurance that will pay for it.

[mit]

.."Mandatory" is the mfr's determination for use in commercial service and for engines still in warranty. It's a good word. I consider the service bulletins mandatory. I carry insurance that will pay for it.

What ever you do is fine. It would be nice if I could afford insurance! But there are many of us that can't. I stand on my statement that we are not doing ourselves any favors by using the word when it is NOT appropriate for the operation!

[GAHorn]

I'm not trying to be argumentive. It sounds as if there might be some other issue that is bothering you.
What would you prefer? An "optional" service bulletin? The mfr considers this mandatory in their view for continued airworthiness of their product. The FAA is bound to support that view because they are the certifying authority and they have to rely upon the mfr for engineering review and support.
The only reason it's not an inspection that is specified for non-commercial useage aircraft is in order to allow owners like yourself an alternative method of compliance with a non-AD event. That should make you happy, I would think.
But in my view, it's Mandatory all right. Very very mandatory....for anyone who takes a serous view toward insuring airworthiness inspection of unknown damage.

Meanwhile,... do you carry liability insurance?

[mit]

I'm not trying to be argumentive. It sounds as if there might be some other issue that is bothering you.
What would you prefer? An "optional" service bulletin? The mfr considers this mandatory in their view for continued airworthiness of their product. The FAA is bound to support that view because they are the certifying authority and they have to rely upon the mfr for engineering review and support.
The only reason it's not an inspection that is specified for non-commercial useage aircraft is in order to allow owners like yourself an alternative method of compliance with a non-AD event. That should make you happy, I would think.
But in my view, it's Mandatory all right. Very very mandatory....for anyone who takes a serous view toward insuring airworthiness inspection of unknown damage.

Meanwhile,... do you carry liability insurance?

No I can't afford it! You cloud the water with your opinion. My very first post is correct IT IS NOT MANDATORY from the REGULATORY side. That is not to say that it may not be a good idea or safer to do as you say. But as the Maintenance man for the organization I believe you should be as accurate as possible. Mandatory Service bulletins from the manufactures that cover there a$$ do not serve general aviation in any way. Unless they are forced to pay for them.... What do you think the chances of that are?

[c170b53]

One mans opinion of a hard prop strike can be interpreted by another as just cutting the grass. Albeit after a strike the thought and fear of losing a prop inflight might be a motivation to inspect further, its just as likely that the prop governor counterweights /gears might fail. How do you really know which component has been stressed by abnormal rotational forces? In my mind any prop blade deformation means teardown and component overhaul. Just my call and one I can live with. On that bidding war internet site there'e a 182 for sale with 4 hrs since major with a prop strike. Ouch!