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Old 02-21-2018, 08:12 PM   #1 (permalink)
motoxxxman
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Posts: 2,152
 

Join Date: Dec 2017
Location: US
Default Learning the hard way...

So I haven't flown my 230s since the last time I crashed and repaired it. One of the things I did when I was going through it was check the tail adapter for straightness. What I never thought about was how far onto the shaft to lock it down. I simply pushed it til it bottomed out on the bearing and locked it in, thinking this was the way it's supposed to be. Now during today's events I'm recalling that when it was new, it had some play. Meaning you could grab the tail motor and pull it in and out a little. With the adapter all the way down the shaft, you can't pull the motor in and out at all.

Well, found out the hard way today that this is very incorrect, and a terrible thing to do. Mid flight of my 2nd battery, I was doing some piro's. First I went full left rudder (tail stopped almost dead), then went full right rudder (tail at full speed). This last move must have gotten the tail motor hot enough that it bound up due to the adapter being too far onto the shaft or something, because it came to a near halt at all rudder stick positions and started piro'ing uncontrollably. I immediately flicked it into stability mode knowing I couldn't do this in 3D mode, and came in for a landing while still spinning wildly. As it got close to the ground it started tipping over. Knowing I didn't want to hit the ground under full power, I quickly flicked TH on about 6" off the ground and reduced collective a little. The descent was smooth, but the heli was at about a 45 degree angle, so the blades chopped right into the pavement at almost full speed. The blades hit so hard, it folded one of the stock blades into a V at about a 40 degree angle. One link popped off but didn't break, tail boom bent a little, put a very small tear in the canopy, and broke the tip off a canopy mount that I had previously broken and glued back together.

Main shaft and feathering shaft are still dead straight, blade grips and head still perfect, tail motor still operates flawlessly after it cooled down a hair, and most importantly:
STILL DIDN'T BREAK THE MH TAIL ROTOR!!!

After I conceived my theory of what caused the tail to fail, I fixed the blades, popped the link on, taped the canopy, replaced the canopy mount, bent the boom back straight, and left the tail exactly how I had it. Went back up in the air and replicated the same exact thing; full left rudder for 3 seconds, full right rudder for 3 seconds, tail came to a screeching halt again. I was doing this quite a bit higher this time, and over tall grass. So I did the same, flipped into stability mode, came down slow with it still spinning out of control, and was about to drop it in the grass, and the tail suddenly started working again. So I brought it in for a proper landing. This told me there was an obvious problem with the tail, and the higher altitude gave it a chance to cool a little during the descent, and it kicked back in once cool enough.

So I went ahead and repositioned the tail rotor adapter with a bit of play, allowing the motor to pull in and out about 1mm. Back in the air, full left rudder, full right rudder, full left rudder, full right rudder. Did this for about 2 minutes straight. Tail worked perfectly the entire time. The motor was hot enough to burn my finger when I landed it, but it still worked perfect.

So just for poops and giggles, I put the adapter back down all the way again, and took to the air. Full left rudder, full right rudder... ok, still works... full left rudder, full right rudder, tail stops again and piros out of control. Kicked back in after a couple seconds again though.

Once again, spaced it out a little, tried one last time. With the gap, nothing I did could get it to fail, no matter how long I held full right rudder.

Soooo.... for everyone out there, when installing the tail adapter, do not push it all the way down. Keep a small gap so once it's tightened you can pull the motor in and out 1mm-2mm. I guess I should suggest everyone check theirs now too before the next flight. I'm wondering if some of the motor failures people have had were in fact because the adapter was installed too tight on the shaft.

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Last edited by motoxxxman; 02-21-2018 at 11:46 PM..
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