Thomas coupling
 

The 'thomas coupling', as I understand it this is the 'bit' between shafts transfering power. A kind of spring effect.
Just been reading about the sad failure of the twin squirrel near Middle Wallop and the death of a fine pilot and his engineers.
Totally unrelated to the Thomas coupling issue, that same ramp and roller freewheel is fitted to the Gazelle. I had one fail on a never to be forgotten day just to the north of Stansted. 4 unsuspecting passengers on a joy flight. I thought the clutch had given out and did all the right things keeping power on and returning to land promptly. Had I known then what I know now about coating procedures for ramp and roller freewheels my imagination might have been a little more active!
Top tip, never read obituaries of fine individuals that you have known, makes you feel quite inadequate, and sad.

And I thought it was about a personality disorder...

.....and vulnerable!!!