Has this happened to anyone?

[Craneman]

Any one had this happen to their EB?


This 3mm bolt just sheared in mid flight!!!!
http://i225.photobucket.com/albums/dd239/craneman34/IMG_5987.jpg
Damage report:

Helicam solutions E4 mount damaged plus tilt servo stripped
http://i225.photobucket.com/albums/dd239/craneman34/IMG_5983.jpg
Canon HC5 camera really F&%! up
http://i225.photobucket.com/albums/dd239/craneman34/IMG_5984.jpg
Main carbon fiber blades split
http://i225.photobucket.com/albums/dd239/craneman34/IMG_5988.jpg
Helicopter is fine but I need to check the spindle and servos.

[rkeith2]

Man thats a shame -

I did have a lube issue on the output shaft that caused some binding and got me by surprise yes, but, lack of oil and preflight check did me in.

From what I can see it appears that the slider is not running on a dry shaft.

[kelly steed]

I use this just for the amount of time a camra and gear is hanging.

[cbergen]

I typed a reply last night, then lost it.....

As stated in other areas, this has happened before, I believe for various reasons.

These may or may not apply to your case, but are possibilities.

1. Defective bolt. How would any of us know without NDT of each one.

2. Bad design. It has been appx a year and half since the last reported incident, which is when we amended the assy instructions on how to properly install this bolt. That's a LOT of new Helicopters out there, combined with all of our birds sold before that means one heck of a lot of them flying all the time with no problem.

This design, or this setup is NOT new, nor is it strictly used by us on Bergen Helicopters. Many of the currently flying heli's from other manufacturers use the same design idea with a bolt going through a bellcrank, threaded into an arm as the pivot point.

So what can go wrong?

3. If the bolt is too tight, add some vibrations from any number of sources, the bolt can shear.

4. If the bolt is LOOSE, allowing too much play on the bellcrank, add any vibration, the bolt can shear.

5. Travel limits of the gyro/servo combo. If the travel limits are such that the pitch slider can bottom out in either direction but the servo is still trying to move farther, that places the strain on the pivot point (the bolt), which over time at least, can cause it to shear. Obviously this would not happen in flight or you are doing some SERIOUSLY fast pirouettes (:) ), but I have seen setups where on initialization the tail servo goes HARD over for a second, usually with Futaba gyros and a JR tail servo, or a 2.4 ghz system that has not been failsafe set properly.....

There are many things that CAN go wrong with a helicopter, ANY helicopter, and no way to guarantee that an incident will never happen. When we identify an issue, we either redesign, change materials, change how we install the item(s), or change their inspection criteria (watch it more closely).

Carefully look over the heli for any hidden damage, Bearings, shafts, etc, and put a list together. We'll see what needs to be doen to get her back up and flying. I know Jody will take care of the mount (besides electronics), but the camera is the worst.....:(

[Craneman]

Thanks Chris, the truth is given the situation I think I managed to avoid quite a bit of damage, I managed to stay cool, then put the landing gear down after that I cut the motor, (had to look at the radio for a split second cause I couldn't find the the switches!) then figured out what the heli was doing by then I was maybe 30 feet from the ground and falling fast! so I gave it full pitch and managed to slow it down quite a bit before crashing.

Not really sure about the what caused the bolt to shear though, Gyro settings are ok not binding in any direction, and the truth is I can't remember how much I tightened the bolt during the assembly. The heli suffered very little damage, only main blades and tail boom support that goes on the tail boom cracked, I still have to check spindle and bearings and shaft but they seem to be ok.

Chris I'll place an order for some new blades and the support soon.

Yes Jody is replacing everything for free and The camera had a protection plan so I might get a new one for free.

If all goes well I'll just need to pay for new blades, tail boom support and a new 3mm bolt!