Hiller 12E Rotor Systems

ROTOR  tuning - Hiller UH12E

1.       Bending both tabs up makes the collective light, mostly when pulling the  first bit of collective up from the bottom.

 2.       Sweeping both blades aft makes collective light, mostly when pulling first bit of collective up from the bottom.

 3.       If collective is light only when collective is way up (High Power), as when operating with very heavy loads (i.e. 3100lb gross weight and in a turn), try adjusting the collective bungee attached to the firewall downward a quarter inch at a time.

 4.       Sometimes the centre of pressure marks on a main rotor blade are not in exactly the right place (somebody measured wrong when he put the target stickers on the blade).   Check the Structural Repair Manual for the correct position of the centre of pressure.

 5.       Hiller has balanced the rotor system (after master balance of the head assembly alone) by adding weights to the paddles for chordwise balance instead of sweeping the blades.  This has had no adverse affect on smoothness in flight, in fact some of their smoothest machines were balanced this way.

 6.        Hiller found that the main blades can both be swept forward an equal small amount to cure a light collective when pulling the first bit of collective from the bottom.  This and step 2 above should be tried only after tab bending, bungee adjustment, down stop washers and flyweight washers doesn’t cut the mustard.

 7.       One M/R tab thickness equals approx. one and one-half degrees of tab angle.

 8.       Be sure the rubber boot the left collective passes through doesn’t offer any friction to the stick.  This, or any similar friction can cause the collective to feel to be different at the same power setting, depending whether that power setting was approached from a higher or a lower power setting.

 9.        Remember that bending the tabs out of the streamlined position causes drag and robs horsepower.