Prop Strike Query

[Dick]

Nosegear failed during taxi and had a wooden prop strike on pavement. prop
is toast but wondering about the old C-85. consensus is leaning towards
everything okay if no vibration and tracks true upon startup of new,
balanced prop.

comments appreciated, Dick

[Ron Natalie]

Dick wrote:
> Nosegear failed during taxi and had a wooden prop strike on pavement. prop
> is toast but wondering about the old C-85. consensus is leaning towards
> everything okay if no vibration and tracks true upon startup of new,
> balanced prop.

Continental will tell you that any prop strike requires an engine
tear-down. (Lycoming will give the same story). My insurance
company didn't even bat an eye when I submitted the bill for my
(wasn't even an engine stoppage, the tips just scuffed a tiny bit
as the airplane slid off the runway after the tire blew).

On a sudden stoppage, I would certainly heed this advice. I don't
know anybody fool enough to believe that there might not be internal
damage.

[Matt Whiting]

Dick wrote:
> Nosegear failed during taxi and had a wooden prop strike on pavement. prop
> is toast but wondering about the old C-85. consensus is leaning towards
> everything okay if no vibration and tracks true upon startup of new,
> balanced prop.
>
> comments appreciated, Dick
>
>

What does your A&P say? I think you are also likely OK with the wooden
prop making the strike as it is unlikely that you had the sudden
deceleration that a metal prop strike can cause. However, I'm not an
A&P so what I think doesn't mean diddly to the FAA. :-)


Matt

[Roger]

On Fri, 12 Nov 2004 19:31:04 GMT, "Dick" > wrote:

>Nosegear failed during taxi and had a wooden prop strike on pavement. prop
>is toast but wondering about the old C-85. consensus is leaning towards
>everything okay if no vibration and tracks true upon startup of new,
>balanced prop.

Continental now says tear down on anthing more than something that
requires dressing the prop. I believe Lycombing is the same.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


>
>comments appreciated, Dick
>

[Charlie England]

Roger wrote:
> On Fri, 12 Nov 2004 19:31:04 GMT, "Dick" > wrote:
>
>
>>Nosegear failed during taxi and had a wooden prop strike on pavement. prop
>>is toast but wondering about the old C-85. consensus is leaning towards
>>everything okay if no vibration and tracks true upon startup of new,
>>balanced prop.
>
>
> Continental now says tear down on anthing more than something that
> requires dressing the prop. I believe Lycombing is the same.
>
> Roger Halstead (K8RI & ARRL life member)
> (N833R, S# CD-2 Worlds oldest Debonair)
> www.rogerhalstead.com

And there is a new AD on Lycs that says to remove the accsy case to
inspect a gear if the prop even hits *grass*.

Let your intellect and your trusted A&P be your guide when you decide
what's safety related, what's futile attempts at lawsuit avoidance and
what's revenue generation.

Charlie

[Nathan Young]

On Fri, 12 Nov 2004 19:31:04 GMT, "Dick" > wrote:

>Nosegear failed during taxi and had a wooden prop strike on pavement. prop
>is toast but wondering about the old C-85. consensus is leaning towards
>everything okay if no vibration and tracks true upon startup of new,
>balanced prop.

Wood prop or not, teardown. Yes, the wood absorbed a lot of the
energy of the strike, but a good amount of energy was absorbed by the
internals of the engine. No way I would fly behind a prop strike
without a teardown, especially one severe enough to shatter the prop.

As a few others posted - if you have insurance, now would be a good
time to exercise it. Most insurance companies would rather pay for an
engine teardown & new prop now vs. a total + medical + liability in an
accident later on...

-Nathan

[Bill Daniels]

"Dick" > wrote in message
om...
> Nosegear failed during taxi and had a wooden prop strike on pavement.
prop
> is toast but wondering about the old C-85. consensus is leaning towards
> everything okay if no vibration and tracks true upon startup of new,
> balanced prop.
>
> comments appreciated, Dick
>
>

I'll strongly support the consensus views here.

I had a prop strike on an Archer (Ex-wife screwed up a landing) The engine
didn't stop but about two inches of each prop tip were bent.

I hassled the insurance company into paying for a teardown in which I
participated. The mechanicals were OK but the shock had dislodged tiny bits
of sandcast flash that were in the oil galleys. It took a month of careful
cleaning to remove this stuff.

I was less than happy that Lycoming hadn't cleaned up the case casting but
thankful that the teardown found the problem.

Bill Daniels

[John_F]

I believe that there is a new AD that any sudden engine stoppage
requires a engine tear down and inspection.

On Fri, 12 Nov 2004 19:31:04 GMT, "Dick" > wrote:

>Nosegear failed during taxi and had a wooden prop strike on pavement. prop
>is toast but wondering about the old C-85. consensus is leaning towards
>everything okay if no vibration and tracks true upon startup of new,
>balanced prop.
>
>comments appreciated, Dick
>

[D. Reid]

Well..lets review the facts.
Prop strike during taxi. My bet is engine was throttled back to idle.

Wooden prop involved. Yes...wood absorbs a tremendous amount of stress. A
high rpm out of balance condition was most unlikely and sudden stoppage was
most unlikely as well. My guess is...the engine just "spooled down" under
resistance of the prop being "ground away" (sorry...but no pun intended).

So..Being as we are discussing this subject in "rec.aviation.homebuilt" I'm
going on the surmise that the subject A/C is a non-certified engine.

What would I do? I would NOT tear the engine down. For starters. Lyc and
Cont WANT you to do this...not merely for safety sake...BUT because they
want to sell you rebuild parts and componets. Think about. Here you have a
totally dissasembled engine laying on your shop bench and in ALL probablity
checks out just fine. ADMIT it...are you going to put the engine back
together with the same parts that came out of it? Not likely. (what is the
worse that can happen in THIS instance???...a bent prop flange!!!...and
thats about ALL !!! So...if its bent it could be cracked...ok, I'll buy
that. Only thing left to do...CHECK IT OUT !!!...but you dont have to tear
the engine down to do it !!!

Think you broke a crank???...not likely...bent a rod?...probably not.

Here's what you do.
Do a runout measurement of the crank/prop flange (on a C-85 I think .006 is
the max runout). If it's less than that...do a dye penetrant check on the
accessable areas around the flange...if it checks good...install a fresh
prop and go FLY !!!...I WOULD! If the dye check, shows a crack...well your
screwed.

A decent, honest shop should charge about 3 bills max to do this! Of course
YOU have to supply the prop. :-)

Dont assume the worse...but DO take steps to rule it out.

Hope this helps.


"Dick" > wrote in message
om...
> Nosegear failed during taxi and had a wooden prop strike on pavement.
prop
> is toast but wondering about the old C-85. consensus is leaning towards
> everything okay if no vibration and tracks true upon startup of new,
> balanced prop.
>
> comments appreciated, Dick
>
>

[Ron Natalie]

D. Reid wrote:
< For starters. Lyc and
> Cont WANT you to do this...not merely for safety sake...BUT because they
> want to sell you rebuild parts and componets.

I doubt it...the amount of parts you gotta put into an engine (uneless
you're going after the cylinders or something) is TINY. I suspect the
major reason is they care concerned about liability. Most of the cost
in the tear down is LABOR.

[Dan Thomas]

"D. Reid" > wrote in message >...
> Well..lets review the facts.
> Prop strike during taxi. My bet is engine was throttled back to idle.
>
> Wooden prop involved. Yes...wood absorbs a tremendous amount of stress. A
> high rpm out of balance condition was most unlikely and sudden stoppage was
> most unlikely as well. My guess is...the engine just "spooled down" under
> resistance of the prop being "ground away" (sorry...but no pun intended).
>
> So..Being as we are discussing this subject in "rec.aviation.homebuilt" I'm
> going on the surmise that the subject A/C is a non-certified engine.
>
> What would I do? I would NOT tear the engine down. For starters. Lyc and
> Cont WANT you to do this...not merely for safety sake...BUT because they
> want to sell you rebuild parts and componets. Think about. Here you have a
> totally dissasembled engine laying on your shop bench and in ALL probablity
> checks out just fine. ADMIT it...are you going to put the engine back
> together with the same parts that came out of it? Not likely. (what is the
> worse that can happen in THIS instance???...a bent prop flange!!!...and
> thats about ALL !!! So...if its bent it could be cracked...ok, I'll buy
> that. Only thing left to do...CHECK IT OUT !!!...but you dont have to tear
> the engine down to do it !!!
>
> Think you broke a crank???...not likely...bent a rod?...probably not.
>
> Here's what you do.
> Do a runout measurement of the crank/prop flange (on a C-85 I think .006 is
> the max runout). If it's less than that...do a dye penetrant check on the
> accessable areas around the flange...if it checks good...install a fresh
> prop and go FLY !!!...I WOULD! If the dye check, shows a crack...well your
> screwed.
>
> A decent, honest shop should charge about 3 bills max to do this! Of course
> YOU have to supply the prop. :-)
>
> Dont assume the worse...but DO take steps to rule it out.
>
> Hope this helps.

Runout doesn't tell the whole story. The crank may have bent
enough to crack (doesn't take much) and sprung back to within limits.
Wooden props would have a hard time of bending it enough, though,
especially at idle.
Small Continental cranks have a habit of cracking between the
first and second rod journals (numbered from the back of the engine).
Don't know why.

Dan

[John Galban]

"Dick" > wrote in message >...
> Nosegear failed during taxi and had a wooden prop strike on pavement. prop
> is toast but wondering about the old C-85. consensus is leaning towards
> everything okay if no vibration and tracks true upon startup of new,
> balanced prop.
>
> comments appreciated, Dick


A few years ago I met a guy loading a Champ (with a C-85) onto a
truck at a backcountry strip. He told me an amazing tale of his
crankshaft snapping in flight over some seriously rought terrain
(Great Bear Wilderness Area near 8U4). As it turns out, he had just
enough altitude to glide to the strip and made a safe landing.

I asked him if he knew why the crankshaft snapped and he had no
idea. While I was looking over the plane, I noticed that the metal
nosebowl had a small dent and asked about it. He told me that he'd
taxied into a snowbank several months earlier. When I asked if he'd
torn the engine down he replied that he'd hit the snow bank slowly at
idle, and was sure that the engine wasn't damaged. Supporting his
assumption was the fact that the plane had flown a whole 20 hrs.
without a problem since the prop strike.

Spontaneous crankshaft breakage doesn't happen very often. You be
the judge.

John Galban=====>N4BQ (PA28-180)

[Ernest Christley]

John Galban wrote:

> Spontaneous crankshaft breakage doesn't happen very often. You be
> the judge.
>
> John Galban=====>N4BQ (PA28-180)

Sure they do. Just ask Amy Laboda.

<flamesuit on>

One more reason I like my rotary engine 8*)

<INCOMING!!>

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http://www.ernest.isa-geek.org/
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