Broken bell crank, DO NOT FLY WITH OLD STYLE!

[lcyrace]

Today was the maiden flight for my EB and the first time out with the DX7. WOW, what a great flying heli and the radio is awsome.

Now, I talked to Bergen on Thurs and they are sending me the upgraded bell-crank for the tail. I asked if the old one would be ok for normal flight, no 3d or crazy aerobatics. They said that would be ok but don't be too arrgessive until I get the new part.

Today, on the 3rd flight as I made a fairly fast straight pass in front of me, I noticed the tail start to drift. As I tried to correct it woud drift more. After the 3rd attempt to correct the tail it went into unstoppable piroettes, nose right. I immediately threw the hold switch but didn't have enought time for it to get stop piroetting before impact. Boy I tell you what, a 15lb heli makes one hell of a thud...

Here is a pic of the bell-crank. Is this the failure that was corrected with the new part?

[Whirly-Girl]

Are you sure you saw the heli going hard right?

Someone correct me if I'm wrong, but with the direction that our main blades rotate, a loss of T/R control would induce a hard nose-LEFT piro. Could your broken piece be from the crash?

I crashed my Bergen this summer because of a hard nose-RIGHT piro from forward flight and it was in fact caused by a GY401 hard-over condition. I sent 2 of my gyros into Futuba to be checked out (weird how this happened twice in the same day...once in a T-Rex). I received 2 brand new replacement gyros - with no explanation, except "Replaced under warranty". Just a bad batch of gyros and bad luck for me.

Jeanette

[MarkWebber]

Jeanette is right. Broken bellcrank yeilds l/h turn. I had a bellcrank break and there isn't any slow transition into loss of control. Immediate piro's to the left. No worries now with the new bellcrank, however.

Check out that gyro, as Jeanette noted.

[Gary Travis]

The condition you have described, I think may have been caused by something other than the belcrank. As Mark stated there would be imediate loss of rudder control. The slow loss or softening of control tells me that it was caused by one of two conditions I have seen several times before. The first would be a lean condition causint the gyro to constantly work the servo, this in turn causes the servo to overheat and stall. The second being a faulty gyro. It has been my experience that reason number one would be the culprit. I have seen this many times in the past, not only on the Bergen gasser but several other brands as well. I myself had it happen two or three times on a glow heli in the past.
Gary

[Greg Alderman]

Jeanette and Mark...yes a loss of "tail rotor" (i.e. the tail rotor stops spinning, for what ever reason) will cause an uncontrolled fast left hand piro...BUT if the tail rotor is still spinning and you lose tail pitch control...that is another ball game...I had a couple of the old style bell cranks break on me while I was fighting a VERY bad vibration that was found to be the OS 91 SZ pumped motor I put in it...that OS was causing so much hi freq vibe in the tail push rod that it snapped the bell crank (and popped the rod off the ball a couple of times!)...most of the time the heli just went into a uncontrolled SLOW piro to the right...a couple of times it was a pretty fast piro to the right...I don't seem to remember it ever piro'ing nose left on me...just depends on how the tail blades "feather" when pitch control goes away...

By the way...the old tail bell crank has been used with very few problems for many, many years now...it was sufficiently strong enough for a heli that had been tuned properly and was not seeing a lot of hi freq vibes...most of the broken tail bell cranks have been on heli's that the G26 was not running smoothly and causing a lot of vibes...the G23 didn't seem to vibe as badly when not tuned correctly...and such we were not seeing the bell crank break...

[MarkWebber]

just depends on how the tail blades "feather" when pitch control goes away...

Excellent point! Thanks for helping me out of the "box". :roll: Guess I just lucked out in the direction of my piro, huh :arggg:

I've no doubt that vibes helped contribute to my failure. I'm just glad that Chris engineered a more cutomer proof bellcrank for us :noteworthy