Proven Condition Monitoring Solutions

Balancing Tail Rotors

When balancing a tail rotor, particularly a light 2 blade type found on a H-500; SA-3130 Alouette II or AS-350 Ecureuil you can often find that the yaw pedal position can influence the Tail Rotor Radial balance levels. The example in Figure 1 shows a change in balance levels from 0.42 ips with Right pedal forward to 1.10 ips with Left pedal forward.

This can easily mask the effect of small weight changes and lead operators to assume that the balance solution was incorrect and to situations where operators have re-calibrated the balance.

On initial data collection it is recommended that Radial Balance data is obtained on the Ground at three conditions. First with the pedals Neutral (use ‘Ground’ for this collection). Then with some degree of Left Pedal forward, (use ‘Hover’ condition for this collection). And then with Right Pedal Forward, (use ‘1’condition).

The amount of pedal input applied is of course at the discretion of the pilot, but make sure that it is always the same. Figure 1 shows a typical example before and after balancing, where the move lines are all parallel and the final balance is the best obtainable compromise.

It is very important that the pilot establishes exactly the same pedal positions between each balance check.