Afternoon Gents, I'm having some maintenance issues with the collective friction lock.
Does anyone know how tight it should be with friction fully applied and how loose with friction off?
One of our pilots seems to think it should be impossible to move with full friction on with hyds running and it should rise up on it's own with fully off with hyds still running.
The maintenance manual contains some explicit warnings regarding setting maximum friction, and there have been some pretty close calls when the max stop is not adjusted correctly and the friction actually stops the use of the collective - hence the variety of emergency release mechanisms (pip pins) installed on various operators aircraft. Glazing of the friction face is the major cause of inadequate friction, but also worn chrome on the collective, or bent collectives cause some of the more unusual irregular friction problems.
The collective should be neutral and neither raise or lower by itself. The basic rigging process will address the the adjustment of the collective balance spring; but if the rigging is correct, then a collective open loop adjustment on the aux pack will remedy the situation.
Any good S61 engineer or mechanic will know this, and as always the manual details precisely how to accomplish this task - and of course will be referenced in the appropriate maintenance entry.
We always did dual inspections on any adjustment or maintnenance activity on the collective friction - a good plan based on some of the things I have seen people do to them!
