Prop position

My suggestion - Could just be lower internal friction due to oil
viscosity, or even the engine simply breaking in. I'd almost be more
concerned about why it always stopped horizontally, as at least most
broken-in 4 cylinder engines stop with the prop at 45 degrees (10:30).


First verify that the mags actually do indeed shut off, then kill the
engine with the mixture, and do a hand prop to see if all cylinders
feel the same. Only if there is a noticeable difference, get a
compression check.

"nrp" wrote:

My suggestion - Could just be lower internal friction due to oil
viscosity, or even the engine simply breaking in.

The engine is well broken in. 300+ hrs. since a top overhaul.

I'd almost be more
concerned about why it always stopped horizontally, as at least most
broken-in 4 cylinder engines stop with the prop at 45 degrees (10:30).

Really? This seems to vary among the O-320 and O-360 engined aircraft I see
on the ramp. I'll do a more careful survey next time I'm out there.

First verify that the mags actually do indeed shut off, then kill the
engine with the mixture, and do a hand prop to see if all cylinders
feel the same. Only if there is a noticeable difference, get a
compression check.

Did that. They feel the same.

--
Dan
C172RG at BFM

More thoughts -

Your prop just might be indexed correctly but differently than the ones
I'm recalling. That seems to be a snake oil thing with different
aircraft.

Another lo-cost check would be to do an oil analysis on a sample. I
know of an engine that would get really stiff when warm that had a bad
cam lobe & misc bearing contamination. It would free up on cooldown.

I contend the equal cylinder-feel-on-hand-prop test is an effective way
to check out the upper end of an engine, although it would not uncover
any lower end mayhem. An oil analysis is the cheapest way to check or
track the lower end. Be sure to take the sample correctly though.

In rec.aviation.owning nrp wrote:
: Your prop just might be indexed correctly but differently than the ones
: I'm recalling. That seems to be a snake oil thing with different
: aircraft.

There was a thread on this awhile back. I'd concluded that at least on the PA28
like mine, the discrepancy is in the service manual itself. It calls for 10-2 IIRC, but
doesn't say if it's as viewed from the front or the rear. So, 50% of them out there are on
one way, and the others are 60 degrees off. I *still* don't know which is right.

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

On Mon, 20 Mar 2006 19:57:03 +0000 (UTC),
wrote:

In rec.aviation.owning nrp wrote:
: Your prop just might be indexed correctly but differently than the ones
: I'm recalling. That seems to be a snake oil thing with different
: aircraft.

There was a thread on this awhile back. I'd concluded that at least on the PA28
like mine, the discrepancy is in the service manual itself. It calls for 10-2 IIRC, but
doesn't say if it's as viewed from the front or the rear. So, 50% of them out there are on
one way, and the others are 60 degrees off. I *still* don't know which is right.

Mine stops with the prop @ 2 O'Clock as viewed from within the cabin.