Prop friction torque procedure

by Rich Provenzano in 912 / 914 Technical Questions 9 years ago

I seem to remember a diagram where a scale, like a fishermans scale, was placed at a distance from the tip of the prop. Down pressure was then applied and the value, in pounds, measured.

I've looked through the LMM and only found how to do this after a prop strike. This procedure is much more involved than what I described above.

Has anyone used the scale method? If so, what is the direction of the pull force and the pounds of pull for acceptable value.

Rich

Re: Prop friction torque procedure

by Dave Rigotti » 9 years ago

Dave Rigotti

11 27 0

Check the video section for your answer.

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Re: Prop friction torque procedure

by Roger Lee » 9 years ago

Roger Lee

127 5.2k 4.78k

Hi Rich,

You will need to put in place the crankcase locking pin. Now the prop can only move a few degrees and then come to a stop because the crankshaft won't turn. I leave my long 6" Tee handle Allen wrench in the locking pin as a red flag so I don't forget it and leave it in.
Now measure out from the prop hub center anywhere from 26-30 inches. You don't want too short a measurement as it makes the prop too hard to turn. Take some twine and hook up the scale on your mark. Pull the prop through its short arch and see what the measurement is. I do it a couple of times and take the average as it can vary slightly.

Now multiply the number on the scale times the inches you measured out from the center of the hub.

Example:

28 inches x 16.5 = 462 inch/lbs

Put this number on your maint. Checklist and in your logbook.

What I usually see as normal is 425 - 490 in/lbs

Don't forget to remove the crankshaft locking pin. Forgetting to remove this and trying to start the engine will cause you some serious heartache.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Thank you said by: Rich Provenzano

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Re: Prop friction torque procedure

by Rich Provenzano » 9 years ago

Rich Provenzano

20 59 30

Thank you both for your replies.

I was unable to view the video and had to recover from a previous date. All is well now and I re-watched the video.
Just couldn't remember where I saw it.

Thanks for the tip and explanation.

Rich

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Prop friction torque procedure

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