Responsible actions after prop strikes

This morning, I wrote to EAA as follows:

In my recent search to buy either an RV-3B or an RV-4, I have encountered three different aircraft that have had prop strikes. The owners' actions in these varying and different circumstances ranged from doing nothing to having the engine disassembled and thoroughly inspected for any damage. All these aircraft were offered for sale with varying explanations as to how the damage might have happened, but in each case the owners did explain that such damage had occurred.

All of us are wary, or should be, of an engine and prop that has suffered a prop strike, and my question is:

What is the appropriate and necessary action that ought to be taken after any prop strike -in the interest of everyone's safety, and liability- (for both experimental & standard category aircraft), and what are any legal ramifications that might develop in the situations where an engine and/or propeller had been inspected in accordance with acceptable practices/procedures, as well as in a case where and engine and/or propeller had not been inspected in accordance with acceptable practices/procedures?

As a paralegal, I am prohibited from offering legal advice, but should be free to quote other knowledgeable parties, so I have refrained from advising anyone that they "should do" thus & such not only to protect themselves after a prop strike, but to protect others who might fly an aircraft that might have suffered damage, either apparent or undetected.

Any advice that you may be able to offer concerning the legal or ethical responsibilities that pilots have in the unfortunate occurrences of prop strikes will be much appreciated.

Thank you.

Sincerely,
Claude "Barney" Barnhart
--
Claude Barnhart, CP?
Certified Paralegal
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Any prop strike strike requires teardown.

Lycoming considers ANY prop strike to be very serious. Even if it did not noticeably reduce rpm. Besides possible damage to the crankshaft itself, it is likely that the bolt and dowel pin on the crankshaft gear may be damaged.
I have seen this damage even with very minor prop strikes.

Lycoming says...

Exactly as Mel says....

The Lycoming document with their definition of "Prop Strike" and the actions they require is here...

http://www.lycoming.com/support/publications/service-bulletins/pdfs/SB533A.pdf

gil A

Does anyone know what the procedure / recommendations are for a Subie set up? They have such a lite prop, and a gear box to absorb energy I was just wondering if anyone has had to deal with this scenario and what the outcome was.

With all the emotion removed from this discussion a minor prop strike will likely not cause damage but it can. I have heard Continentals are more likely to crack a crank because they are more brittle than Lycs. honestly I don't know.

To solve your dilemma put one bullet in a revolver and spin the cylinder. Now if you put the gun to your head and pull the trigger it 'probably' won't go off.

Is probably good enough??

You don't have to actually break the crankshaft on a Lycoming to cause big problems. The gear at the end of the crankshaft that drives the camshaft and the accessories is bolted on. Just loosening that bolt could really ruin your day.

I suspect that to be mostly the reason they send out the SB every year telling you that even a minor strike warrants a teardown inspection.

Edit: Yeah, just like Mel said. D'oh!

Well lets put it this way, the feds felt it worthwhile to issue a AD for propeller strike inspections on Lycoming engines, AD 2004-10-14C. To me that tells the importance of actually taking one apart and looking at the appropriate parts.

prop strike cautionary tale

In a previous life I was the maintenance officer for a (very well maintained ) C172 flying club. At about 2400 hours, we decided it was time for the big teardown. The engine had always ran great, but was slowly losing power and in the last 50 hours started making big iron in the oil (it was a worn out cam).

During the rebuild (which I helped on a lot) we sent the crank out. What a suprise when it came back unservicable with a big internal crack. I'd flown this plane, a lot, with wife & kids.

I dug out the logs, and did a careful review. Way back in the mid 70s when the plane was new, the logs were like this:
oil change
oil change
annual
oil change
oil change
new prop
oil change
...

There was no detail about why there was a new prop... The mechanic was long sice gone. I asked around, and finally found someone who remembered that the plane was taxiied into a hanger.

Moral of the the story for me - teardown and send out the crank after any prop strike. I don't like to think about what might have happened.

BTW - it cost an extra $4200 for the new crank.

IowaRV9Dreamer said:

In a previous life....prop strike cautionary tale

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Great and scary story. The crank is so very critical. If all manufacturing, inspections, installation and operations are done properly than its reliable and something you can trust you family in. Well manufacturing is out of our control but operations and compliance with mandatory prop strike tear down is. Don't mess with it. I know a guy who bought a used Lyc (with a known "minor" prop strike) and put it in a Glasair with out tear down. On his first flight he took off and climbed like a crazy straight out and the cranked failed. With luck and winds he did a 180 and landed on the same runway opposite direction, just. I bought a O360 with a prop strike which was alleged to not be making power when the prop hit the ground. I did the tear down and it turned out, it was OK. I am glad I check it out.

Now to be a little wishy washy, if its a wood prop its more likely not to damage the crank than a metal. It takes nothing way from the cautionary tales above.

Reply from EAA

EAA's reply to my query:

Hello Claude,

According to the engine manufacturers, the only acceptable response to a propeller strike is a complete tear-down and inspection of all internal components. In the case of Lycoming this recommendation has been carried to the level of an Airworthiness Directive, whereas Continental has remained with only a service bulletin to this effect.

Many mechanics have differing opinions as to whether this level of reaction is always warranted or not, and there are lots of opinions as to what might be appropriate in a given situation. However, there is no clear guidance beyond what the manufacturers have published, so any decision made in the field that is not in accordance with manufacturers? instructions is solely at the discretion of the mechanic and aircraft owner involved.

Joe Norris
EAA 113615 Lifetime
Senior Aviation Specialist
EAA Aviation Services

EAA?The Spirit of Aviation
Phone: 888.322.4636 Extension 6806
Fax: 920.426.6560
***********************

Thanks to Joe Norris for his prompt reply. And, thanks to fellow RV-ers who have responded likewise.

Suffice it to say that an entry should be made in the logbook that an inspection and reassembly had been accomplished in accordance with FAA AD 2004-10-14, or more appropriate wording to that effect.

Barney

What's the typical going rate for a teardown and inspection...

What's the general going range in $$$ for a teardown and inspection...
... considering they find no internal damage? I'm planning on going the taildragger route and probably will start off with a wooden prop or the 3 blade composite.

Stan

It Depends...

If I was flying behind it, a complete teardown and inspection is what I would require and that is supported by engine manufacturers. Someone who wants to move the engine will often come up with many reasons why it is not required.

I once went to buy an engine from someone who sells a lot of second hand engines to homebuilders. I was pretty keen and the aircraft was described to me as "wind damaged". The logs looked good and the engine had 200 SMOH.

On a whim I punched in the N number of the aircraft it had been removed from, just before I rang the seller to buy. I found the pictures of the aircraft and NTSB accident report. It had been "flown" through a barb-wire fence in a runway overshoot. Both props looked very mangled in the picture.

Of course I offered the seller core value on condition the crank passed inspection. He declined and offered to remove the accessory case and replace one of the gears as per AD. I have never heard back from him, but I am confident there is an Experimental aircraft out there flying with that engine, probably completely unaware of its history.

I now own a Mattituck engine (new) after this and a number of other experiences. Bottom line is that there are very few good deals out there. If you are not absolutely sure of the history of the engine and/or pricing a bulk strip into the deal to find out exactly what you got, walk away. You and your passengers depend on the engine for your survival. Save some money on the avionics and paint if you need to.

Of course I am somewhat conservative, many others are not. Each person needs to make up their mind what sort of risks they are prepared to take.

Richard
RV7A - Finishing

I'm not going to advocate NOT tearing it down but perhaps some consideration should be give to what type prop and what did it hit.

Could be different response to a wood prop hitting a mole hill getting mud on it vs a metal prop hitting concrete causing engine stoppage.

I saw a turboprop get two engine changes after it was taxied through a snow berm that was only 10 inches tall. Props only had six inches or so of ground clearance.

Prop Strike

Since you are considering an experimental, you can reason your own definition of "responsibility" as it relates to "prop strike" and "risk tolerance." The government trusts you to make the decision.

Van's website "cost estimator" lists "mid-time used engine" as one of the possible cost line items. I embarked on a quest to find one. After a while, I got worn down spending time on it. They are hard to find. Finally, I started to consider Ebay offerings. A dandy looking (rattle can repainted) mid-time, light prop strike unit came up for auction. The engine had not been torn down in any way. The seller?s description had phrasing like; bolt on and go, die tested, flange +- .002. I consulted my spam-can mechanic and he suggested requesting a photo of the prop. Great idea!! The photo shows the seller's definition of "light prop strike." Do you agree Claude? What do you experts think? The seller could just as easily been a flying RV owner; now for sale. The engine sold for $7,2XX.

Not Me!

No way I would fly that engine without a tear-down inspection. I've seen too many crankshaft gears come loose after minor prop strikes. And that one doesn't look minor to me.
Another thing to consider. Who's to say the seller didn't "tweak" the prop before taking the pictures?

Listen, guys...

....to Mel and the other Tech advisers!

I'll repeat this post for the newbies on here. Several years ago, a Piper lost the engine at night after departing Augusta, Ga and climbing to 5000 or so, and was vectored to Wrens, Ga airport, 15 miles north of my home base.

They came up less than 1/4 mile short and the result was a fireball and five fatalities. Yep, the engine was a H2AD, single drive double mag and the shaft had broken. Further investigation revealed a prop strike to a dirt berm over a year ago, with no major damage and no teardown.

I saw the wreckage while it was still smoldering...ugly sight indeed.

You guys feelin' lucky?

$$$$$$$$ for prop strike inspection & compliance with AD

I spoke yesterday with an owner who had had a dirt-prop strike recently.

Cost to crate/freight/inspect/comply with AD (no damage) & return, from Memphis to Custom Airmotive in Tulsa - $3000.

pierre smith said:

... Several years ago, a Piper lost the engine at night after departing ...

... Yep, the engine was a H2AD, single drive double mag and the shaft had broken...

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The H2AD on a Piper?

I thought this engine was a C172N-only powerplant.

Here's one that's kind of off topic but not really. One day a few years back my son and I were taxiing behind a twin when one of the props on the twin struck and demolished one of the taxi way lights. I didn't see it happen but Tom did and told me about it. I parked the plane we were flying and decided to walk over to tell the pilot what had happened. As I suspected he hadn't even realized he'd struck anything. When looking at the prop the damage was clearly evident, the first inch of one blade was neatly curled over. I don't know what he did about it; I didn't stick around to see. If you were this guy what would you do?

Park it and get on the phone.

Rivethead said:

Here's one that's kind of off topic but not really. One day a few years back my son and I were taxiing behind a twin when one of the props on the twin struck and demolished one of the taxi way lights. I didn't see it happen but Tom did and told me about it. I parked the plane we were flying and decided to walk over to tell the pilot what had happened. As I suspected he hadn't even realized he'd struck anything. When looking at the prop the damage was clearly evident, the first inch of one blade was neatly curled over. I don't what he did about it; I didn't stick around to see. If you were this guy what would you do?

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For starters I'd make three phone calls. One to my insurance carrier, one to the airport authority, and one to my favorite engine shop.

John Clark
RV8 N18U "Sunshine"
KSBA