R-22 structural failure?
 

This is from Kathryn's Report of 27 Sept, 2020:

Kathryn's Report

A very strange incident.

Cheers,
Grog

Tail rotor drive shaft damper failure? There is a yellow arc on the RRPM

As there are no supports or bearings along the length of the shaft, it is possible to thrash the shaft around at certain RPM or above the normal range as well. One of the many compromises of the design, reduces cost and complexity.

Could be "whirl mode".

Has happened before - UK Whirl Mode Accident

Tinkicker

Hmm, a Mariner,...in Florida?

I'm gonna guess someone mistook a pontoon for a gator, shot at it, missed, and hit the tail instead. :bored:

I had trouble accessing the accident report via the above link to Kathryn's Report, which linked me to a Cirrus accident. I don't know what happened with the initial link, but I was able to find the NTSB Preliminary Report, via another approach.

The link to the NTSB Report:

https://app.ntsb.gov/pdfgenerator/Re...relim&IType=LA

I hope this link doesn't change.

Cheers,
Grog

That explanation makes a lot of sense. It is quite possible that the gator, being in heat, mistook a pontoon for a scaly, saurian lust object, misjudged his approach, entered "whirl mode" and wound up getting shot at for his efforts. The errant shot went wide and struck some sort of vital tail rotor drive bit, and things went down hill from that point on.

Other than the gator's wounded pride at his misdirected lust, there were no reported injuries.

Cheers,
Grogt

,...or maybe upon seeing the gator making love to his pontoon freaked the pilot out, causing him to jerk the throttle wide open, which led to an overspeed,...then "bang", tail falls off! :}

Maybe the R22 decided it was a gecko, and on getting a fright, shook its own tail off and ran in the other direction?

Hmm! R-44 pilot flies aircraft in dodgy conditions, which has precisely what to do with the whirl mode of the TR drive shaft?

Hilico - :ok:this looks like someone caught out above cloud trying to find a way down and getting into a 'sucker's gap' before CFIT (or UCFIT) ends the day.

That's not the accident that is the subject of this thread; however, it is interesting, and thanks for posting it. For some reason, the link in my Post #1 has become corrupted and no longer leads to information on the subject crash which involved a Robinson R-22 Mariner and which occurred at Fort Myers, Florida on 06 September, 2020. The best I can do at this point, is just refer you to the link in my Post #6 which leads you to the NTSB Preliminary Report of the 06 September accident. I just clicked on the Kathryn's link in my Post #1 and it led to a discussion of a crash of a Piper P-18A.

Technology is great when it does our bidding.

Cheers,
Grog

The link is not corrupt, you simply posted the wrong link. You can't post the landing page of Kathryn's site, which is what you did, because it always changes content. You have to post the specific report url from the list on the right hand side of her page:

Kathryn's Report: Robinson R22 Mariner, N194HC: Accident occurred September 06, 2020 at Page Field (KFMY), Fort Myers, Lee County, Florida

Okay, I think I understand. Thanks for the explanation. I thought that the link was to the story itself and not a link to the "landing page", but that's obviously not the case in this situation. I'll be more careful in the future.

Cheers,
Grog

I spoke with the gator after the incident, he claimed strongly it was worth it and he'd do it again.

Since when is there no bearing and damper in a R22 tail rotor driveshaft?

As distinct from, say, a B47 or a B206, which has multiple hanger bearings and driveshaft segments, I see from the parts cattle-dog that the R22 has only one damper close to the front, and the rest of the shaft to the tail rotor gearbox is able to wobble to a fair extent.

I say this with the uncertainty that comes with time, first flew those things in 1988 and the memory may have faded a little, and I don't recall seeing such an item as the damper back then...

No support bearings, just a "lightly loaded" damper bearing.

Certainly not rigid by Bell's standards but obviously more than sufficient, and as you allude to, a lot lighter. Your original statement gives the impression that there's no support between the intermediate and aft flex-plate, your second statement somewhat corrects that. :ok:

Not unusual though.

Hughes 500/300 are similar with just a damper ring no bearing.

https://www.atsb.gov.au/media/24549/...502316_001.pdf
Report on MD 500e shaft failure