Prop position

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 *
************************************************** ***********************

I once prop-positioned a cutie on the ramp... If you must know, I
crashed and burned... :-(

Did your propposition involve 10 o'clock and 4 o'clock?

.... or was it something about being horizontal?

Did your propposition involve 10 o'clock and 4 o'clock?

.... or was it something about being horizontal?

LOL. The usual "approach" has something to do with picking her up at 10
and dropping her off at 4 G

wrote)
... or was it something about being horizontal?

LOL. The usual "approach" has something to do with picking her up at 10
and dropping her off at 4 G


"I'm not that kind of girl - SLAP!"

"Contact."


Montblack :-)

I once prop-positioned a cutie on the ramp... If you must know, I
crashed and burned... :-(

How did that happen, did you pull the 'we're out of gas' trick?

("Ben Smith" wrote)
I once prop-positioned a cutie on the ramp... If you must know, I crashed
and burned... :-(

How did that happen, did you pull the 'we're out of gas' trick?


She informed him of the "Pop-up" TFR:
Sorry, can't.
Huh?
The "President" is coming for a visit.
Huh?
The "P-R-E-S-I-D-E-N-T" is visiting ...for a week.
Oh .....pause ....OH! ....pause .....Doh!


Montblack
That's alright, we can still cuddle.
Yeah, ok, sure ...whatever.

[Dictionary.com]
yeah
adv : not only so, but; "I therein do rejoice, yea, and will rejoice" g

I'm pretty sure where the prop stops doesn't measure anything.
How do you know it stopped in the same place "horizontally"
each time? There are at least two possibilities.

Why would the prop stop in a preferential position anyway?
Seems like it would be on any one of the 4 compression strokes.

I'm also convinced that even the differential compression
check doesn't show what you really want to know.
The rings are AC coupled, tho less so in the Lycomings.

So I'd guess one would need something worse to worry
about. Maybe price of gas or user fees!

Bill Hale

wrote:
I'm pretty sure where the prop stops doesn't measure anything.
How do you know it stopped in the same place "horizontally"
each time? There are at least two possibilities.

Right, unless you can somehow distinguish the two blades.


Why would the prop stop in a preferential position anyway?
Seems like it would be on any one of the 4 compression strokes.

There are 4 cylinders, and each one has a compression stroke every 2 revolutions
of the crankshaft. That makes 2 compression strokes per revolution. The prop
stops in one of two places, which are indistinguishable unless you can somehow
distinguish the two blades.


I'm also convinced that even the differential compression
check doesn't show what you really want to know.
The rings are AC coupled, tho less so in the Lycomings.

What does this mean: "The rings are AC coupled"?


So I'd guess one would need something worse to worry
about. Maybe price of gas or user fees!

Agreed. It's fun to think about, though, and if there's a sudden change in
behavior, I'd want to know what changed.