April 2000 in a Jet-Banger flying through a narrow gorge on an overcast day with approx 1500' cloudbase. Aircraft in the cruise when the input shaft to the MR gearbox failed. Sudden yaw with loud noises and engine overspeed, even though the engine out warning (audio & light ) were on. Luckily saw the needles had split the "wrong" way and kept the throttle wide open.
Managed to put the helo down on a tiny bit of sand on the riverbank. All happened in a matter of seconds; felt like a lifetime.!
Only damage to the machine was a minor nick in the T/R driveshaft cover and one blade. Four on board and we all walked away.
Slung the machine out the next day with a Mil8
Verdict; All four bolts holding the gear that runs inside the splined shaft of the coupling had sheared due to heat fatigue. 9 hours since maintenance had worked on it and replaced the seal and allegedly re-greased it. My own eyes could see there was no grease in it and have the photos to prove it, however, and here's the scary part, the AMO concerned were like lawyers and bank managers....untouchable.
Another hard lesson learned
