bluercpilot
02-18-2008, 04:02 PM
I replaced my tail shaft yesterday and discovered a potential hazard.
When replacing the shaft I initially installed it such that the end of the shaft was flush with the outside edge of the Aluminum Tail Rotor Hub (EVPL# 116). When I set up the tail rotor pitch slider throw, I discovered that moving the pitch slider to full throw towards the boom caused the linkage between the Pitch Control Ball Link (EVPL# 120) and Tail Rotor Blade Grip (EVPL# 115) to over-center. The caused the Tail Rotor Pitch Control Slider (EVPL# 112) to lock against the hub requiring quite a bit of servo force to breakout and move back in the other direction. Had this happened in flight, I'm sure it would have been quite ugly. At a minimum, it would have resulted in some pretty uneven tail control at full throw.
As it turns out, the flat in the tail rotor shaft is long enough to allow some movement even with the tail rotor hub set screw engaged. I ended up moving the shaft as far as possible into the aluminum hub (set screw as close to the boom as possible) and this kept the linkage from over-centering. I recommend that you do the same. You should see about 1/16 inch of shaft sticking out of the aluminum hub end.
When replacing the shaft I initially installed it such that the end of the shaft was flush with the outside edge of the Aluminum Tail Rotor Hub (EVPL# 116). When I set up the tail rotor pitch slider throw, I discovered that moving the pitch slider to full throw towards the boom caused the linkage between the Pitch Control Ball Link (EVPL# 120) and Tail Rotor Blade Grip (EVPL# 115) to over-center. The caused the Tail Rotor Pitch Control Slider (EVPL# 112) to lock against the hub requiring quite a bit of servo force to breakout and move back in the other direction. Had this happened in flight, I'm sure it would have been quite ugly. At a minimum, it would have resulted in some pretty uneven tail control at full throw.
As it turns out, the flat in the tail rotor shaft is long enough to allow some movement even with the tail rotor hub set screw engaged. I ended up moving the shaft as far as possible into the aluminum hub (set screw as close to the boom as possible) and this kept the linkage from over-centering. I recommend that you do the same. You should see about 1/16 inch of shaft sticking out of the aluminum hub end.