Prop strike

[N95334]

Well had a bad day. My 1946 BC12D with a Cont 65hp and alum prop taxied into a Citabria. The prop sliced through the wing of the Citabria and hit the spar right at the wing strut fitting. The prop is bent on both ends and a chunk of alum about the size of a dime is missing where that blade hit the metal strut wing fitting.
What do I do now? Does the engine have to be torn down? Has a flange hub. I was not there when it occurred so I don't know what RPM it was running at the time and did not check if the prop would turn etc.
Thank God no one hurt, just my buddy's pride and wallet.

[magman]

Re: Prop strike

Check it out with AOPA but my belief is that since no one was injured it is an INCIDENT & NOT an ACCIDENT.

As such there is not a Reporting Requirement.


If you have Hull Insurance it's time to get an Estimate.

Note that insurance never pays for a Major Overhaul; just a teardown & DAMAGES.

Corrosion & wear is not Incident Damage.

Assure the FUSELAGE is examined here also & the Engine Mount sent out.

I've seen windshields pop out after a strike.


If no Hull I would still tear the engine down.

The "Old School" of just dialing the crank won't help if there is a crack.

[guns68]

Re: Prop strike

a prop strike that bent the blades, you are going to have to tear down the engine. Magman is right, send out the crank and have it inspected. I'd have to look at the regs to be sure, but you might want to do the same with the cam shaft. Man, I'm sorry this happened.

[Ragwing nut]

Re: Prop strike

taper cranks not known for cracking, BUT, I would do a teardown and runout on crank. magnaflux prop hub as well, it is probably cracked. I would also blast the mount and check for cracks to be sure.

[Garry Crookham]

Re: Prop strike

Here is Continental's official position on prop strikes: http://www.tcmlink.com/pdf2/SB96-11B.pdf
Service bulletins are not mandatory for Part 91 ops, however is would be a good idea to have the crankshaft magnafluxed. The core business at the shop I work at is engine overhauls. We see one to two prop strike engines a month. The 6 cylinder Continental engines usual don't show any major problems unless they were running at a high power setting. 4 cylinder continentals don't fare as well. The crankshafts seem to be a bit brittle and if a metal prop is involved, the crank will usually be cracked.
In the past it was an acceptable practice to dial gauge the crankshaft after a prop strike and if the runout was good return the engine to service. There are some airplanes flying now with undetected cracked crankshafts due to this. The owner usually finds out about the cracked crank when he has the engine overhauled.

Garry

[guns68]

Re: Prop strike

I found this from Harry Fenton's website

Prop strikes are a very serious condition, regardless of the engine. Both Continental and Lycoming have Service Bulletins regarding prop strikes, so it is not a small matter. Inspecting the engine is more than just checking runout of the flange- bearings can become dislodged, connecting rod bolts can get stretched, the impulse couplings on the mags can engage at too high of an rpm. Issues which are harder to find are cracks in the gear teeth of the engine drive train. For example, when the crank suddenly stops, the gear teeth can be jammed together, resulting in a crack in the bottom apex of the gear tooth.

I know this is not the FAA speaking but I think it's prudent advise non the less.

[Hank Jarrett]

Re: Prop strike

When you get the crank out there is a little trick that can save you the cost of the magnaflux test if your crank is cracked. Hang the crank with a piece of coat hangar wire and tap it with a screwdriver (NOT IN A POLISHED OR MACHINED AREA!!!!) It should ring like a bell. If it "thunks" there is a really high probability that it is cracked and you will probably be able to find it visually. If you find the crack, there is no sense doing the NDI.
PLEASE NOTE!!! If it DOES ring, that DOES NOT mean it is un-cracked! You STILL NEED TO DO THE NDI! Sometimes a part can ring with a crack, but in 20 years I NEVER saw a steel part that "thunked" that didn't have a crack in it somewhere. If it "thunks" you save the cost of NDI, but you have to get a new crank. Consider it a discount on the new crank.
Hank

I'm a Scott, I could never resist going over the part till I found the crack. Just couldn't BEAR to toss a part unless I was SURE it had that crack. And THESE parts belonged to the Navy!

[jim cooper]

Re: Prop strike

The advise given seems excellent. I'd opt for tearing it down, getting things checked as they advise you. MIGHT save your life! JC

[astjp2]

Re: Prop strike

Dial it and if it's good, fly it. Dont waste the money on a 65 teardown if nothing is bent. Continental lawyers say that if the prop hits a blade of grass, its a prop strike and must be tore down. Most inexperienced people worry about the crank, I am worried about the plastic mag gears. Sudden stoppages are real hard on mags. Tim

P.s. just stirring the pot some

[N5002M]

Re: Prop strike

Dial it and if it's good, fly it. Dont waste the money on a 65 teardown if nothing is bent. Continental lawyers say that if the prop hits a blade of grass, its a prop strike and must be tore down. Most inexperienced people worry about the crank, I am worried about the plastic mag gears. Sudden stoppages are real hard on mags. Tim

P.s. just stirring the pot some

LOL..thats awesome Tim!! You are stirring the pot and I like it!!! I wrecked a Aeronca 15AC and I hired this old timer to help me get it flipped over in which we did. The wing strut was bent among other things. He ratchet strapped a 2x4 to it and I had borrowed a prop with the intent of flying it outta there. I dialed the prop flange and it was WAY out...like .040!!!. He took an adjustable wrench and bent the flange back to about .010. I stood there looking at the plane...he said "well, get in and fly the thing home...Jesus, I'm tired and hungry" I said "you come with me..." he said "No!!!"...we disassembled the plane and hauled it out on a flatbed. LOL....I just couldn't do it. I really didn't care about the engine flying apart, but that dang lift strut really bothered me.

Long story short...I had the engine overhauled (well, AVEMCO did) and I bid out (AVEMCO paid me to rebuild the wing) the airframe work myself. The plane was in the air a month and a half later. I sold the plane for $28K more than I paid and the new owner flipped it into a creak bed about 3 months after I sold it. It's now 5 years later and the plane is rotting into the ground. Sad to see....

Chris

[Mark Julicher]

Re: Prop strike

Don't forget that the Slick magneto service manual requires a mag overhaul after a prop strike. Perhaps that is also true on other makes of magneto.
The accessory gears take a beating too.

[T.Taylor]

Re: Prop strike

Just saw something that made me feel strange, I was asked to ferry a Mooney that had a gear up landing, the owner, a DR. said I was too expensive, he had the gear lowered, a two blade prop installed in place of the three blade that got bent????, he is on the NTSB website were the prop came off (maybe the crank failed) just after take off, died on airport property, T.

[M Towsley]

Re: Prop strike

And Darwin raises his ugly head, again. Good call on your part. Apparently his arrogance overrode his common sense he should have had. I would go play the lottery if I were you. Perfect example of what can happen after a prop strike.

Here is the link: http://www.ntsb.gov/aviationquery/br...18X33733&key=1

[T.Taylor]

Re: Prop strike

And Darwin raises his ugly head, again. Good call on your part. Apparently his arrogance overrode his common sense he should have had. I would go play the lottery if I were you. Perfect example of what can happen after a prop strike.

Here is the link: http://www.ntsb.gov/aviationquery/br...18X33733&key=1

Yes, that is the one, never met the guy, talked with him on the phone, I just can not understand someone putting a two bladed prop on that engine