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/publ...dfs/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 :D) 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. :eek:

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.

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