Almost lost prop

[scard]

Originally Posted by DanH

This should help Ron....written by Henry S. Rose, Chief Engineer, Sensenich, back in the good 'ole days:

Wow, super cool! I consider that, outside the box engineering simplicity that many of us have almost lost .

[Ron Lee]

Thanks Dan. Looks like 0.10 inch should be adequate. I did measure everything when I converted from an Aymar Demuth prop to a Catto several years ago but it helps to have info like this.

[MNForrest]

Originally Posted by sandifer

According to the IAC contest results this Forrest fella is pretty good in his S-1S too. Did you fly Sebring a couple weeks ago? I attempted to CD the Carolina Boogie last weekend, but had to cancel due to Wx. Major bummer.

Yes, Sandifer - I flew Sebring. My first attempt at Intermediate, after all winter off. It was rough. Had to bail before the unknown to make it home for Mother's day, but I was just happy to get some time in the box in front of critical eyes.

Forrest

[WillyEyeBall]

Would like to thank all the responses and valuable information on this incident. I'll let everyone know what we find when the engine is opened up, and the replacement components, including a new prop that we will install.

Bill McLean
RV-4 Slider

[steve91t]

I have a question, is giving the prop a tug or two as a pre flight going to allow you to detect a prop that's starting to come loose? I'm assuming that if it's at the point where you can feel play, it's too late.

Steve

[TThurston]

The rental plane I fly, a Diamond DA-20 C1, has mandatory 50 hour inspections to retorque the bolts on it's Sensenich wood prop. My ground instructor had his prop fall off during a flight, and was able to glide to an airport and land safely. As I recall his story, there was really very little warning before losing the prop. The engine suddenly seemed very rough - shaking so much that he shut it down. The next instant, the prop was gone and everything went quiet. He said it was really quite peaceful.

So during preflight I aways try to look beneath the edges of the spinner and yank on the prop to see if anything is amiss. So far no problems.

[Mel]

I didn't notice anyone talking about humidity. This is one of the major reasons for re-torquing a wood prop frequently. If the prop is installed when the humidity is low, the prop will swell as humidity increases resulting in the bolts being over-torqued. On the other hand if the prop is installed during high humidity, the prop will shrink as the air dries out and the bolts will actually become loose.
Wood props should be re-torqued more often in areas where there are significant changes in humidity.

[Ron Lee]

Originally Posted by Mel

On the other hand if the prop is installed during high humidity, the prop will shrink as the air dries out and the bolts will actually become loose. Wood props should be re-torqued more often in areas where there are significant changes in humidity.

There may have been a prop departure in the west not too many years ago on a canard that was based on the east coast. Perhaps it was a humidity change issue.

[PCHunt]

..........When you re-torque a wood or other prop, you should first back every bolt off a bit, then re-torque them all in proper sequence. Then check tracking.

Don't just add torque to an already torqued bolt.

[Mel]

Originally Posted by PCHunt

..........When you re-torque a wood or other prop, you should first back every bolt off a bit, then re-torque them all in proper sequence. Then check tracking.
Don't just add torque to an already torqued bolt.

Don't re-torque immediately. Give the prop a little time to "relax" before re-torquing.