Jerry Cochran

Jerry Cochran

Well Known Member
I'd like to get some input from all Lyco experts out there. Let's say you have an O-360 just overhauled by a VERY reputable and well known shop. Then at under 50 hours, just well broken in, one has a mishap and bends prop.

According to Lyco, this engine MUST be torn down, inspected, and put back together with new bearings, etc. Other licensed shops say just dial the crank flange and if OK, go and fly.

I've also noted chatter in the various forums like "Well, what's it dial?" implying that just dialing it is "good enough" Please help me lower the confusion...

I am looking at an engine that had this problem, just trying to find it's worth.

Jerry
 
Sudden stoppage with enough force to bend the prop also puts undue stress on other "spinning" components, such as those attached to the accessory case, like Magnetos. There are drive pins back there that can get stressed/bent. Sure, there are examples out there of those who have not done a teardown aafter a sudden stoppage, and they have not had any problems. I personally am aware of one that braked too hard on grass, went up on the nose and back down, bending the prop and minimal cowl damage. NO teardown, and it has flown for 7 years now without a problem. If it was mine, I would have torn it down before I put my family in it. Everyone's level of risk is different. You might also ask the insurance company if they would require it to be torn down.

Vic
 
Let's say you have an O-360 just overhauled by a VERY reputable and well known shop. Then at under 50 hours, just well broken in,
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Not too sure of the relevance of any of this :confused: The engine is now unusable IMHO.

If there were any mitigating factors, where some might consider of a pragmatic view, they would along the lines of wooden prop? Grass? Low RPM? Even then a strip down is the "correct" action I think...

Just my 2cs worth ;)
 
In trying to determine its worth, I would say first dial it in. If the crank isn't bent, then it is worth (IMHO) somewhat more than core value. The cylinders should be good. It should be torn down, however, and there MAY be other parts needing replacement. It the crank is bent, it is worth less than a basic run-out core at least to me.

Bob Kelly
 
One of the main concerns with a prop strike is that no matter how minor it seems, it still stressed the spinning internals of the engine. Especially the drive pin and attachment hardware at the accessory drive end.
Lycoming says a tear down is required.
Yes, there are probably some good usable parts. But I certainly wouldn't put my Family behind it without a proper tear down and inspection. (That's of the engine, not the Family:))
 
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Both Lycoming and Continental require a tear down inspection if the prop is damaged. All sorts of stuff CAN happen inside. You could get lucky but you also could not. Most any insurance company will pay for the tear down and rebuild , assuming there was insurance.

Personal experience. We have a 172 with an O-300. Parked, tied down. A freak gust of wind picks up the tail ( no rope there), lifts plane, strains a wing rope which breaks, stands plane up on the tripod of it's nose, left gear and left wing tip. 20 minutes later another gust blows it the other way and it lands on it's gear with a bunch of folks standing around watching. It was a sunny day, not a cloud in the sky( eastern Washington), and my son was only going to town for 2 hours. The 182 next to him flipped over on its back, no tie downs at all.

We removed the spinner which was cracked, ( one tip of prop was bent a tiny bit from contact with the asphalt), duct taped the wing tip, got a ferry permit, test ran it like crazy, and he flew it 2 hours home with no effect on flight at all.

We then removed the wing for repair to the outboard 5 feet. Insurance company wanted to tear down the engine, I said that seemed silly, it only had 600 hours and was not running. They paid for wing repairs, a prop overhaul, a new spinner and all my labor ( I am an A&P with IA). We flew happily into the sunset....UNTIL....8 flying hours later when the oil change came due. The screen was FULL of chips of aluminum.

Called the insurance company back, they said, go ahead and remove it and have engine shop tear into it. The shop found the piston pin cap on cyl 1 and 2 were worn down to a small pea size. No explanation given. I bought 6 new cylinders and spark plugs, and had the mags looked over, the insurance company paid for all the rest. We have a fresh overhaul now.

What caused this? Ins. Co hired an engine expert, he came to no conclusions. I suggested that since the airplane stood on its nose for 20 minutes all the oil drained forward and some got behind the piston pin caps, then when the engine ran, the pressure from heat pushed them against the cylinder wall and ground the soft aluminum to bits against the hard steel cylinder. They decided they could neither prove nor disprove my theory and decided to pay the claim since we had a record of clean oil prior to the incident. ( AIG, in spite of their financial track record they treated us right)

All I am trying to say here is that an engine pedigree is important. If you don't know the history of good engine operation then you have to be suspect.
 
I purchased an IO-540 that was a prop strike. The flange dialed .008". I disassembled engine per Lyc SB and sent all the required parts out for inspection/repair. The crank was straightened (thank god!) for about $900 with a yellow tag. All the other parts passed inspection and were yellow tagged. This was a low time engine, 491 hours SNEW with just a little over 100 hours since factory crankshaft SB compliance which included all new bearings ect.. I replaced the rod bearings/bushings. and just freshened up the cylinders before reassembly with required new bolts, ect... I got about $3000 into the teardown and reassembly. Granted its now an experimental IO-540, but I got lucky and now have a late model 2001 Lycoming for under $16K.
 
!!

Mel is right on the money... so to speak. If you bend the prop, there have been some absolutely fantastic shocks through the engine and components. Regardless of what the rules say, remove it, send it to the engine shop and have them go all the way through it. I've seen some wild stuff with engines and I don't ever care to have an engine failure. Also... have your engine mount and mount points inspected as well. That force goes to the airframe. Best of luck.
Best
Brian Wallis
 
Call your insurance company, they will cover the cost of this incident.

BTW, it will cost you a bit less than $8000 for a tear down, inspection, and reassembly. More, if they have to put new parts into it.

All the accessories should also be inspected; mags, fuel pump, vacuum pump (if you have one.), etc.
 
Brian is right

I saw the aftermath of a prop strike in DIRT. Replaced prop, crankshaft, magnetos, engine mount, etc.
 
Jerry Cochran said:
Great comments/wisdom,so keep 'em coming...

Jerry
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Hi Jerry,

You want more pile on or someone to say its OK, go fly. :)

There are lots of prop strike engines in salvage yards with and without bent flanges....that's where this engine belongs.

If the price is right, buy it and have it torn down by BPE in Tulsa. When you get it back it will be first class engine.
 
N941WR said:
Call your insurance company, they will cover the cost of this incident.

BTW, it will cost you a bit less than $8000 for a tear down, inspection, and reassembly. More, if they have to put new parts into it.

All the accessories should also be inspected; mags, fuel pump, vacuum pump (if you have one.), etc.
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Bart at Aerosport Power does prop strike inspections for about $4000 plus any parts required.
He is very knowledgeable and I know he would be wiling to talk with you about the issues related to the decision you have to make.
Give him a call...

1 250 376-2955
 
rvbuilder2002 said:
Bart at Aerosport Power does prop strike inspections for about $4000 plus any parts required.
He is very knowledgeable and I know he would be wiling to talk with you about the issues related to the decision you have to make.
Give him a call...

1 250 376-2955
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Scott,

Good to hear. That number I put up there came from talking to three other reputable shops, but not Aerosport Power.

The high price might be due to parts availability on my O-290 and includes shipping.
 
rvbuilder2002 said:
Bart at Aerosport Power does prop strike inspections for about $4000 plus any parts required.
He is very knowledgeable and I know he would be wiling to talk with you about the issues related to the decision you have to make.
Give him a call...

1 250 376-2955
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Scott,

I called Bart and was quoted $5500 for teardown, new bearings, etc. Glad I haven't purchased yet as this info is helping a lot. In summary, I guess a teardown is called for regardless of how the crank "dials"...

Local shop who I trust a lot quoted 40-45 hours @ $64 per, abour $3000. If I buy it probably go with them.

Jerry
 
Cracked Crankshaft

A friend of mine had a prop strike and found a crack on the center journal of the crankshaft. This is not the usual place they crack and the insurance company paid for a new one.
 
Jerry Cochran said:
Scott,

I called Bart and was quoted $5500 for teardown, new bearings, etc. Glad I haven't purchased yet as this info is helping a lot. In summary, I guess a teardown is called for regardless of how the crank "dials"...

Local shop who I trust a lot quoted 40-45 hours @ $64 per, abour $3000. If I buy it probably go with them.

Jerry
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Sorry Jerry...guess I was off a bit. Come to think of it that price in my head is at least 3 years old now (I'm surprised I even remembered it :p)
 
Danger Will Robinson said:
I found this page.

http://www.mattituck.com/articles/ss.htm

It's Matitucks opinion on this.
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Wow - that's more generous than I would have thought. So, unless the prop stops in "one revolution or less" the FAA does not consider it "sudden stoppage."

I can envisage circumstances where the engine rotates several times, striking the prop "a little" each time but not stopping for several revolutions.

Makes you scared to think of what might be out there on the used market...
 
Engine Sudden Stoppage

What is a prop strike? Is it a sudden engine stoppage regardless of the cause? Is it an occasion when a prop blade strikes a foreign object and the engine continues to run? Is it hitting a rock or other loose object with a prop blade while operating on a runway or taxiway? Is it when something or someone impacts a prop blade when the engine isn't running?

The only pertinent F.A.A. definition that I have been able to find is in Advisory Circular 43.13-1A. It defines a sudden engine stoppage as; stopping an engine in one revolution or less for any reason, be it from propeller impact or from an engine failure of some sort. Both Continental and Lycoming engine manufacturer's have service literature that explains the desired course of action after accidental propeller damage. They also define what their interpretation of a propeller strike is in that literature.

T.C.M.'s Service Bulletin 96-11, in a nutshell, says that if a propeller must be removed from the aircraft to be repaired following a propeller blade impact of any sort or if the engine physically lost R.P.M.'s from the incident, then the engine has experienced a propeller strike and it should be removed from service and completely disassembled and thoroughly inspected for damage from the incident.

Textron Lycoming, in their Service Bulletin 533A, takes the approach that the safest procedure is to take the engine apart for inspection following any incident involving propeller blade damage. However, they have the caveat that the inspecting mechanic may override that position and return the engine to service without disassembly and inspection if he feels that it is the prudent and responsible thing to do.

Textron Lycoming has also published Service Bulletin 475C which requires, in the event that the engine has experienced a propeller strike, inspection and possible rework of the accessory gear train as well as the rear of the engine's crankshaft. Compliance with this service bulletin is mandatory in the eyes of the F.A.A. by A.D. note 2004-10-14, if and only if, the engine has experienced a propeller strike as defined in the context of the A.D.. It should be noted that to comply with A.D. note 2004-10-14, the engine does not need to be completely disassembled and that access to the accessory gear train can be accomplished, in most cases, with the engine still installed in the aircraft.

What this all boils down to is that in the case of any accidental damage to a propeller installed on a aircraft operating under Part 91 of the F.A.R.'s, it is up to the inspecting technician to determine if the engine should continue in service without total disassembly and inspection. A Textron Lycoming engine, that is being operated on a Part 91 aircraft, that had a propeller strike, must comply with A.D. note 2004-10-14 and Service Bulletin 475C at a minimum.

Teledyne Continental powered aircraft operating under Part 135 of the F.A.R.'s, that have to comply with all manufacturers service bulletins, would have to comply with Service Bulletin 96-11 requiring total disassembly and inspection after any incident that required removal of the propeller for repairs or if the engine physically lost R.P.M.'s during the incident. An aircraft, operating under the same regulations, that is powered by a Textron Lycoming engine, would have to comply with Service Bulletin 475C after a propeller strike of any kind and would also have to comply with A.D. note 2004-10-14. On these Textron Lycoming powered aircraft, it is the responsibility of the inspecting technician to determine if the engine should be removed from service for disassembly and inspection.

These are the legal requirements as I see them. There may be other additional requirements mandated by insurance policies or engine manufacturer's and or overhauler's warranties. Either may require additional inspection requirements but neither may negate the inspections required by the F.A.R.'s. Never allow an insurance adjuster to dictate the inspection requirements after an incident. Always rely on the inspecting technician, applicable service data and the F.A.R.'s to dictate how thorough an inspection is necessary to continue the engine in service.

After the extent of the inspection has been determined, it is important, as with any major repairs that are accomplished on your aircraft, to find out exactly what is included in the estimate to repair your engine following a prop strike. Are the minimum legal requirements being met? Is the engine being completely disassembled and inspected? What other services or inspections are being performed at the same time as the inspection? If the engine is being disassembled does the estimate include testing after reassembly? Are any of the engine's accessories inspected and if so to what extent? Are there any hidden costs? After finding out the answer to these questions, it's time to discuss with your insurance company what they will pay for and what they won't, before it's a big surprise after the inspection has been completed. Many insurance companies will not pay for any inspection requirements unless damage from the incident is found during that inspection. Others will pay for all costs for the inspection and for any parts needed due to the incident. Still others will only pay for the labor to do the job and will not pay for any parts.

Finding out what needs to be done and whether that agrees with what you feel should be done, who's going to do it and who is going to pay for it, should help make the experience of a prop strike as painless as possible.
by Mahlon Russell

Send your questions, to Mahlon at [email protected]
 
my two cents

1. After a prop strike there is rightful concern about the airworthiness of the engine. This concern can only be answered by inspection and not by hope, prayer, or opinion.

2. Having a shop that has performed approximately 1 prop strike inspection each month for some 20 years, I still cannot tell you which prop strikes cause damage and which ones don't without an inspection. This has taught me that the preceived "severity" of the propeller strike is not a criteria for deciding which engines should be inspected and which ones need no inspection.

3. I personally didn't tear down my engine after I hit the towbar with the propeller and sent it flying across the airport. But then we did one on a Navajo that hit a plastic caution cone that had damage -

4. Engine mounts can also be damaged. That said, my opinion is based on my personal experience and others have views that conflict with mine based on their experience and judgement. I could be wrong.

I have spend many year pondering how to inspect the engine without tearing it down and I have never come up with an adequate method. Your question as to signs to look for - I don't know.
 
I started my project in 2009 with an IO360-A1B6 that came off of a acrosport that had a gear failure, and consequently a prop strike.

The prop flange dialed .003. The drive pin and other accessory case parts looked great. I figured I was good to go.

I built up the empenage in Nov 2009 and then I couldn't get more kit parts till march of 2010. I decided what the heck, I'll pull the steel parts and send them in. Long story short, the forward thrust flange was cracked 1/3 of the way around. Was it cracked at the same time as the prop strike? I dunno, but I'm sure glad I found out about it then rather than when I was flying.

I'm gonna have to go with the inspect it advice.
 
Say?

Is there any other noise-making device in your airplane more important to have going than the one in the front?

C'mon guys...tear it down!


Best,
 
prop strike

Thirty years ago when I was poorer than I am now (I'm still poor), I flew a Cherokee 140. I kept it tied down outside with ropes that passed through old aircraft tires for markers. The front strut on the airplane was low which put the propeller tips closer to the ground. One afternoon while parking the airplane after a flight, the propeller hit the tailwheel tiedown marker and pitched it across the airport. The engine kept running, but the impact put a small dent in the leading edge of one blade. Like I said, I was poorer then, so I had the local A & P dial the crankshaft and we pulled the propeller off for repair. When it came back, we replaced it and I flew that airplane forever before it was sold. Absolutely no problems at all.........BUT I SURE WOULDN"T DO THAT NOW...........ALWAYS TEAR IT DOWN!!!!!!!! Pierre is spot on. It isn't worth the risk. If the propeller left the airplane at 8,500 feet, you would gladly pay for a dozen teardowns not to be in the fix you would be in at that particular time.
 
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