Airboat Lycoming's

Capt.Doug wrote:
"Lou" wrote in message Thanks, I see quite a bit of airboat motors for
sale at 1/4 of the
price of aircraft. I plan on rebuilding anyway, so I figure why not?

Keep in mind that airboaters are not restricted to approved means of
repairing things. For example, airboaters can fill a cylinder head crack
with silver solder. That works for a while and then they radio for a tow
back to the docks. Would you have the same option of getting a tow if you
were flying behind that crack? Airboaters can install and operate propellers
that have problematic harmonic vibrations. The accumulated fatigue cycles on
the crankshaft may not lead to failure until you are flying behind that
crack. An airboater can limp home on 3 cylinders. Can you? It may be a good
bargain, but do yourself a favor and do a teardown.

D.



I agree Doug, I plan on doing a total tear down anyway. Better safe
than sorry.
Now, whats the difference between the airboat motor and a GPU?

Lou

"Lou" wrote in message
ups.com...

"Lou" wrote in message Thanks, I see quite a bit of airboat motors
for
sale at 1/4 of the
price of aircraft. I plan on rebuilding anyway, so I figure why not?


I agree Doug, I plan on doing a total tear down anyway. Better safe
than sorry.
Now, whats the difference between the airboat motor and a GPU?

Lou


Two things.

One. You can actually find air boat motors to buy.

Two. A lot of air boat motors came out of airplanes so they were designed
with a propeller flange and the right kind of front bearing, aircraft style
motor mounts, etc. etc. etc. (Unlike the typical GPU).

If the crank was ground at an auto machine shop they may or may not have
preserved the fillets at each end of the bearing surface. If they ground a
square corner, you will want to replace the crank (assuming the original had
the fillet....). Better shops know not to do this, but you don't know until
you look - eh?

--
Capt. Geoffrey Thorpe
The Sea Hawk At WowWay D0t Com

John, if I'm putting words in your mouth, let me know.

No, you and others have covered the topic well. I was unintentionally
brief and you stepped in and filled in the gap. Thank you.

john smith wrote:
John, if I'm putting words in your mouth, let me know.

No, you and others have covered the topic well. I was unintentionally
brief and you stepped in and filled in the gap. Thank you.

One, as alluded to here, most airboat engines are built totally or
largely from scrounged UNAIRWORTHY parts. Many if not most will fail
under power sooner or later. Airboat use puts a lot of stresses on
these engines not originally figured on and not apparent in most
aviation uses.

Two, what parts in them not unairworthy are likely as not stolen.

Airboaters are slowly abandoning LyCon power. perhaps homebuilders
should more frequently take the hint.

Here's one for sale on Ebay right now
http://makeashorterlink.com/?C32052C4C