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traviscfi
Member Since : 2014
Posts(157)
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R22 Tailcone dents

12-18-2014 08:34:32

Okay guys I need some help, since May 2013 we have had 3 R22 tailcones that have two small dents on the underside of bay 2. The dents are symmetrical on each side of the rivet line approximately mid-line of the bay. They are visually hard to detect however if you run your hand along the underside you can feel them. Each dent measured about .015" in depth and 1" in circumference. I went and met with an engineer at RHC to help determine the cause however they will not look into this unless more are found. They recently had a report from an operator in Germany what had identical damage. The most recent tailcone had only 43 hours since it was installed and we had not conducted any auto rotations as the engine had not been broken in. The aircraft is newly overhauled and I am 100% confident it has not sustained a hard landing. RHC indicated hard landing damage is normally confined to bay 1.

I have attached a couple pictures.

If anyone else has seen this problem can you let me know so we can pressure RHC to look into this further.

Thanks,

Travis
Tailcone2.jpg
Tailcone4.jpg
Tailcone5.jpg

Replies

hoverman
Member Since : 2015
Posts(1)
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01-01-2015 01:24:36
Travis could those dimples in tail cone be from some one had trailered it at one time and did not tie it down right. with them on the bottom of  the tail cone.it had to pushed down to get something like that....
Dennis B.
Member Since : 2007
Posts(26)
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01-02-2015 01:54:29
I've had two of those over the last 25 years and both were caused by a Students head, from not ducking enough when they went under the tail cone.  Both looked just like these pictures.  Two different students a few years apart.
traviscfi
Member Since : 2014
Posts(157)
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01-12-2015 07:37:55
Thank you for the replies, this aircraft only has 42 hours since it was overhauled with a new tailcone and was never trailered. I thought about the damage being from someone hitting the tailcone with their head however think it is very unlikely this happened in the exact same location on both sides of the tailcone on 3 different helicopters. That would be 6 times someone banged their head into the tailcone hard enough to dent it with no one noticing and in the exact same spot. It has to be some kind of dynamic stress but so far we have been unable to determine the cause.
Dennis B.
Member Since : 2007
Posts(26)
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01-14-2015 01:50:45
Well I agree with that. That would be way to many head bumps.  So next thought is how do you check the rear flex plate?  With a step stool or do you pull down on the gear box?  We check it with the use of a step stool. If there is not step stool available then we put it on the wheels.  If the helicopter is sitting on the skids and not on the wheels that would put a lot of stress on that bay. 
Just a thought.
RotorcorpAtlanta
Member Since : 2011
Posts(63)
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01-14-2015 07:36:14
This may sound silly- but do you use strap style blade tie-downs that loop around the tail cone? The symmetry and shape of these dents along with their orientation at the bottom of the cone seems like it might correspond to where the loads would transfer from the tension of a tie-down strap on a windy day.  There is a lot of surface area for those blades to catch wind.