Compass Atom 500 Head Explosion

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I have a Compass Atom 500 that has about 2 hours if that, mostly in hover and trim flights. It's not one of my 'go to ' helis, but I do like it for it's clean design. However, this afternoon, I was chasing a tail tick (I had grounded the boom as suggested) and after getting that almost completely resolved, I spooled up again to check the gyro gains. Just before getting light on the skids, I thought to myself "Man, if the head let go, I'm pretty close to these bla...." ::: POW! ::: Like I was Kreskin, the feathering shaft let go and the blades, grips, et. al., fired off, one into my deck (causing what sounded like a gunshot) and the other blade, whizzing past me, only to be discovered about 100' away.

I was pretty astonished, one, for the thought that had gone through my mind microseconds before the explosion, and two, because I am meticulous in putting my helis together. I build them on a granite surface plate at work so that everything is level, I loctite every single bolt and nut, use nylocks where necessary, use a torque limiting screwdriver with allen bits to assemble (I know, I know), and go over things at least twice.

Examining the parts that were found tells the tale pretty convincingly. I found that the feathering shaft is in perfect condition (<.0002" runout) the threads are perfect (I was hoping to see a broken bolt at least). Both feathering shaft bolts were still attached to the blade grips and no evidence of stripping (the one side that let go has a small burr on the leading thread).

So here's what happened;

With all the care and checklist assembly, at some point, the head was assembled and checked. Then it was disassembled and upon re-assembly, the loctite was omitted. MY FAULT. I am kicking myself in the a$$ for this STUPID mistake. Not only stupid, but extremely dangerous. My dog is STILL hiding in the bathroom and he wasn't even outside!
I also discovered that the Jesus bolt was ALSO LOOSE!. I must have been on NYQUIL when I put this one together.

So kiddo's, take a lesson here. You can be the best, most careful OCD assembler and STILL SCREW UP!. When it comes to the rotating parts, PLEASE PLEASE PLEASE TRIPLE CHECK YOUR WORK.

I was really upset at the heli (having had so many little issues with it) and it turns out that it was me all along.

I hope that this might save someone the same fate. Read and learn.

[ARM_Coder]

You've got the guts to publicize your story, and I applaud you for this. Fortunately no one got hurt, so all you need now is to fix your Atom and keep going.

That reminds me on how error-prone we can be, especially when we start to feel somewhat confident. I'm attending to the Helicopter Commercial Pilot course, and I'm astonished with the amount of silly mistakes I already did since day one, but recently too - even when following a written checklist. Skipped items are very common during the training/learning phase, but can be deadly, so we are told over and over to not rush things and to do the best to adhere to the standards.

Good flying!

[cyclo]

Glad to hear no one got hurt.

[Ah Clem]

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Like those who posted above, I am glad that neither you, nor anyone else (including the dog) was injured.

I have seen this happen several times on 450's and it was spectacular (not in a good way, but nevertheless spectacular). On the one's I saw, the blades shot out and the helicopter dropped to the ground with relatively little damage.

Thank you for posting what caused it-that took guts!

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You know, we all make mistakes, and we also all think that we're immune from making those mistakes. This wasn't the first goof I ever made, and likely it won't be the last. But HOPEFULLY< someone will read this and say "That guy was a dope"... and when he or she is putting their head together, they will remember that "dope" and NOT make the same mistake!

Yes, if no one gets hurt, then it's a good day. In a weird way, I am lucky that it was still spooling up as the only damage was to the blades, the Connecting rods from the blade grips to the swash and lost bearings for the feathering shaft. I've seen 450's do it in flight and as you say, it ain't pretty. Trust me when I tell you that doing it on a 500 is even uglier!

[Raz0rSh4rp]

Had a tail spindle screw break on my G500 in flight the other day. That was pretty wild, but got it down with minimal damage. Can't imagine mains letting go...

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Originally Posted by Raz0rSh4rp

Had a tail spindle screw break on my G500 in flight the other day. That was pretty wild, but got it down with minimal damage. Can't imagine mains letting go...

I hope that you NEVER DO!~

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Just to update. Got all my parts in order and got some time to put my (human) head on straight and get the thing all re-assembled. Turns out that I didn't lose the bearings after all so that was a plus (I now have a spare set of bearings, washers and o-rings).Had to replace a drive tube but ProstarHobby had everything in stock and shipped as per their usual quick service. Also had to change out the tail blades as they must have touched and the CF looks like it's starting to delaminate. Don't need to lose a tail next.

Have to install the blades tomorrow and see what's what. I spooled it up nice as can be. Man, that's a sweet sounding heli!

Good Weather to all of you.