Syclic
Senior Heliman
Location: Northern Hemisphere
| Auto clutchAfter literally 1000's of autos over the past few years on my Hawks and Falcons I have yet to have a bad auto bearing. That being said, A friend had a bad bearing on one many years ago (a Hawk II he baught used) and I have had a bad one on a Shuttle (cracked case), and have had a couple bad ones lock-up on X-Cells.
Note: the symptoms are different. If one has a cracked outer case, then when or if the engine dies it will disengage normally and one will be able to auto, but when one would throttle up, the engine would overspeed. This is because clutch's torrington bearings would not be able to fully lock down. This was the case with my Schuttle and my
friends Hawk II (he had bought it used so I cannot say how well or hard it had been treated) .
On the other hand, as in my X-Cells, if the torrington carriers lock up and the engine quit then it would react just as a heli that does not have an auto clutch. The head speed would decay instantly and one would not be able to auto. If one would keep the power on all flight long, one would complete the flight and never know that the bearing had locked up until he would try to spin the head freely after the flight or until he tried to auto. Fortunately both of these were caught after landing and shutting down the engine. When an auto bearing locks up, one would not even know it and could easily complete the whole flight as long as the engine kept running.
A number of things can cause this. In the case of a heli with a slipper clutch, if the slipper loosened off too much (e.g. if the locking allen screw was not secured properly) this would allow the top securing bushing to rise allowing the auto bearings to slip upward and possibly jam.
If something would try to stop the mainshaft or maingear from turning while under power (e.g. in flight this could be caused by a bad bearing hanging up in the primary drive train) - this would overload the torrington bearings and lock them up. This type of overloading is similar to that experienced when practicing aborted autos by jaming the power on after the blade has slowed down substantially, made even more critical with the type of high power engines we are using today.This is what was causing my X-Cell auto bearings to lock up.
I am sure with a little more time I could think of other things that can cause it. |
