Feathering Shaft effect

[ShinySideUp]

I had a slight bump yesterday; tail boom strike plus stripped servo gear. Am getting new parts but in the meantime I straightened the tail boom as best I could and frigged the servo so the bad part of the servo gear was out of the way then spun up the heli (Blade 400). I didn't take it off the ground because the servo is still u/s but there was a real bad shaking and I'm wondering what could have failed that I can't see that could cause the shake. I'm told in that the feathering shaft is vulnerable in a crash (although obviously anything can break) but could a bent shaft cause the shaking that has appeared. Everything, apart from the tail boom, looks straight though and I would have thought that to cause such bad shaking I would be able to see a part that was damaged.

Any suggestions? I have a boom on order and a new servo so can't test fly until they are fitted.

Martin

[tiddler]

The chances are that both your main shaft and feathering shafts are bent. They rarely survive a mishap unscathed tbh.

[Mslater]

You'll be able to see if the main shaft is bent by just turning it slowly on the bench and 'eying' for any movement as it turns.

To check the feathering shaft - remove the blades and insert a hex driver into the feathering shaft nut at one side. Now turn the hex driver slowly, the whole shaft should turn fairly easily. Whilst turning it observe the other blade grip. It should not move. A bent shaft will cause an up/down movement.

To be certain remove the shaft an roll it on a glass surface - you'll easily see any bend.

Its also possible the thrust bearings could be damaged so worth an inspection anyway.