About that "dial-out"

[mhorowit]

Talking to the A&P about my engine and it's wobbly flange, and the fact that the prop didn't break.

He suggests that whatever caused the wobble happened long ago. What seems odd to me was he said the wobble was not normally checked during an annual.

Is checking the 'dial-out'/flange wobble normally done during a pre-buy? I dont think it was done during mine and that makes sense if it's not done during an annual!

So an engine could have had a prop strike, distort the flange, had the prop replaced by the owner, and as long as it didn't cause the engine obvious harm, would never get checked. I'll check again, but I don't think there is an entry in the logs that says 'prop strike'.

Does it seem odd that something this dramatic wouldn't get checked during an annual?

Sounds to me that the next a/c pre-buy should have the engine's flange wobble checked.

Sound reasonable? - Mike

[crispy critter]

Mike,
that sounds very reasonable.Fred did not do a dial check on the pre-buy becasue,he said for one,there was no indication in the logs of a prop strike and 2) it was not requested.He did say that from now on he would always ask the prospected purchaser/owner if they would like this task preformed during pre-buy/annuall whether there is indication of a prop strike or not.He also said he wished he had done that for you because that makes him look bad if the damage was alredy there.

[paulnuss]

I thought that you should consider the current engine manufacturers stance: any propellor strike, with any kind of propellor on the engine (wood or metal or composite), merits a tear-down and non-destructive testing (e.g. Magnaflux) of the crankshaft and other rotating parts. Plus replacement of bolts attaching accessory drive gears. No matter if the engine didn't completely stop, and was only slowed slightly. as for example hitting grass, snow, or water. Just slowing the engine revolutions for a brief moment, in their current opinion, could have stressed these parts to or near failure. Maybe it's a "cover your butt" thing by corporate lawyers, but that is how they are looking at things now. The reasons are reported failures after repairs from prop strikes of sorts, that didn't include complete engine tear-downs. This of course is different from the old days, when checking crankshaft flange run-out to within specs, and perhaps replacement of accessory-gear drive bolts, was all the regulations required. You might check with your I.A. mechanic where he stands on this issue.

[Garry Crookham]

Paul is correct: both Continental and Lycoming consider prop strikes to be a mandantory tear down situation. This is known as a prop strike inspection. I would estimate that 25% of our business is generated by prop strikes, usually due to gear up landings. We have a couple of engines in progress right now due to gear up landings and one that tangled with a tow bar.
Crankshaft runout is not normally checked during an annual inspection, unless there is some indication that there might be a problem in that area.
Pre-buy inspections are a real problem. I refuse to do them. There are no regulations that address a pre-buy inspection and it is up the the prospective buyer and the person performing the pre-buy to agree on what is to be inspected. I recommend that an annual inspection be performed. FAR part 43, appendix D lists the scope and detail of items to be included in an annual inspection.

Garry Crookham
N5112M
Tulsa, Ok

[mhorowit]

Ron - you are correctly differentiating between the track the prop takes and wobble due to a flange not at right angle to the shaft.
As I understand it, even with the flange wobble, the resultant erratic track of the prop can be off-set by shims and varying the torque on the prop. bolts . - Mike

[jgerard]

I was looking a my friends 85hp T-cart last weekend and noticed the front of his wood prop appears to have been crushed in by the plate about 1/6" to 3/32" . The varnish is all white around the front plate like it has been cracked loose from the wood. I would think this is bad? The plane is being repaired from a ground loop incident, maybe the mechanic should check the track on this prop. I highly doubt the bolt torque has been checked in the last 2 years and this plane sits in an open t-hanger here in Washington.

Jason
N43643

[Frank DeBartolo]

Prop Tracking

Regarding tracking the prop, what is wrong with getting a board and moving a blade to the board and making a mark with a pencil then moving the other blade to see where the blade touches. Thanks,

Frank DeBartolo
N43684
BC12-D

[mhorowit]

It depends on to what the board is secured. Something at least as high as the prop tip (when it's vertical) and steady. Securing the board to a goat is not a good idea. - MIke

[crispy critter]

There is something that you guys are not thinking about.The limits on prop tolerance is much greater then that on the crank.i.e.Your crank may be fine and the prop may be .010 out,for you guys with a wood prop....think about what wood does as the temp and weather changes....that's right,the wood also changes even when hangered.You can not do an accurate crank check by checking where the prop blades hit.It may cause you to break apart an engine that is in perfect shape,or wrose,it may cause you to continue running an engine that is about to leave you hanging.

[stormman]

what if you hit a squirrel?
Tear down?

HATE to say this guys ,.. BUT most of them are probably not checked right and will show up off track.

One of our wiser members once said

" Too much Analysis leads to Paralyysis"
" Go Fly"

[stormman]

Mike
You never said if was a taper crank or a flanged crank.
Taper runout is .008> SOOO .009 ant shit
flanged .005 on the outer edge . did you check the flange with a mike to see if it was indeed round? one little mishap and one small ding make a big difference on a dial indicator.
Try running out the face making sure to hold the end play back.
Hate to say this but someone may be looking for a job
Naa , i didn't hate saying that at all!
What a few thous amoung friends ? Probably been flying like that for YEARS
HELL there is a lot more things to worry about then a off track prop when flying and it would be last on my list
starting with
Good fuel system
mags
control system
you get the picture, shit that will leave your asshole in your throat in a blick of an eye. on take off
prop runout is out there with paint, door handles and bald tires. and lets not forget lights.

[taylorcraftbc65]

Run out

Hey guys, What is so tough about affixing a dial indicator stand to the front of the cowl, or to a adjustable bracket and set the dial indicator to ride on the rear face of the prop hub. That takes any warpage of a wood prop out of the equasion, Then, if the hub is within tolerance, and the prop fails the " chair test ", Or the reverse, then you know where the problem lies.
As far as the question of is the idea of a post strike teardown a
ripp-off, or just prudance, ask yourself this. " Would I be comfortable with my spouse or child flying with me now?" I've hit
sagebrush blowing accross the runway with a composite prop on my ultralight, and have put many hours on that prop and engine afterwards, with no worries at all. If I had hit anything solid, I would have checked it out. I don't invent reasons to tear down motors, I use a little common sense, while realizing I can't park it on a cloud and call Triple-A.

[stormman]

Whats so tough about a dial indicator sent up on the cowl?

Well for you being a motorcycle man , hunter pilot etc , probably not too hard.


BUUUUUUTTTTTT for some jet mechanic's and astronauts its a REAL challenge
Get a group of mechanic's together, and i use the word "mechanic' loosely. give them a dial indicator to do the same task and a few will be soooo farrrr off the mark that you will wonder how they drove to the meeting.

Knowing that you meant crankcase we will strike that remark about a dail on the cowling from record



Remember," half the people you know are below average. "
and
"some people are alive only because it's illegal to shoot them"

[taylorcraftbc65]

Runout

Actually, the way that the cooling shrouds were set up on my plane, its actually a WHOLE lot easier to SECURLY mount the fixture to the nose bowl, not the cowling, as I said earlier, and check the runout from there. all that is required is that the dial indicator does not move relative to it's referance plane, ( the nose bowl in this instance). I could mount it to a sky hook, if it would not move. You are right though, those of us that built dirt-track stock cars before we started playing with airplanes have a better feel for this kind of stuff. You coming to Alliance Norm?

[stormman]

That must be The mother of all nose bowels.
Not Sure about Alliance, sounds good but im trying to purchase a new tig machine and Plasma cutter and im a little afraid that the guys may take to the spirit bottle and take their aggressions out on me because of prior post replys..
The weathers is looking mighty wet back there in Ohio, looks like a guy could drown. at lest that 's what the weather chanel is saying.
Know of any Texan's with an extra wing to pitch a tent under?