Seat Brace – January 1, 1990

CHR is incorporating a seat brace that you may wish to consider.

Cyclic Bearing Support:

Benefit: You can expect a small decrease in vibration readings in forward flight. It has been identified that the cyclic forces coming from the swash causes this bearing support tube to flex, fore and aft, thus amplifying rather than supporting the swashplate control forces.

Instructions: Viewing the photos you can see it simply goes from the side of the Cyclic Pivot Bushing under the front of your seat, down and back to the lower cabin frame. Be sure to clear all controls and you only need large tacks to secure the tube rather than doing full welds in a difficult area. Prime, paint and note in your log.

Also Inspect: Your center support for your Collective Cross Tube behind the seats. It is centered in the frame with a “T” shaped bearing tube that is bolted to a lower tubing support shaped in a “V”. You should find that your bolt is tight enough to secure this bearing tube to the lower support tubing. If loose, it allows the collective controls to flex, again allowing the swashplate to flex, thus inducing more vibration into the helicopter during forward flight.

Control Play: Another item of cause for swashplate play is not having your Cyclic Control Stop collar tight to the cyclic seat pivot bearing. Be sure to inspect both cyclics and work to eliminate the play for both locations. In the above photos you can see a washer shim was used.

These items of inspection / correction will work to remove some of the vibration you find in forward flight. You may find minimal benefit without the use of a vibration balancer but we mention them as they have been consistent for us in the field, on ships with more than 100 hours.

Any and all feedback is appreciated. Contact the factory at tech@safarihelicopter.com.