Talon Universal joint failure

[Orv Neisingh]

Yesterday I was providing a client with refresher training in his 2010 Talon. As we were flying we suddenly lost yaw control and immediately lowered the collective to reduce torque and set it down safely. The helicopter has 350 hours on it with the VPS engine so the tail rotor shaft and Universal joints also have 350 hours on them.

On inspection we found that the front universal joint

had broken due to lack of grease. There was a ring of fresh grease around the inside of the tail boom that was not present before the flight. The grease was retained inside of the orange silicone sleeve but was not in the universal joint at all which was running dry as you can see from the photo. The center pivot of the U joint is frozen solid and will not move. We are making this a 250 hour replacement item as there is no way to inspect the internal lubrication of these joints.

[Tim Morris]

You seem to have all the fun.  Were you flying forward or in a hover?  What airspeed and how much yaw was observed?  Curious if the vertical fin provided enough force to keep the aircraft relatively straight during the event.

[Orv Neisingh]

Tim, fortunately we were at a 3 foot hover moving forward at a walking pace. The yaw was immediate and the ship rotated about 60 degrees before ground contact.

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This is the part number for the universal joint. Thanks to Geno. They are sending them next day and we should have them by noon today.

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The rear U joint has plenty of grease. We had to cut the silicone boot to inspect it. Both are being replaced. I have no idea how the front one dried out when the boot still had grease that splattered in a ring inside of the tailboom.