www.brantly.info

has anyone had problems with dampers? Also outer blade set up, straight? lead? or lag?

During set up for initial ground runs, we would align the trailing edge of the outboard blades with the line of rivets on the trailing edge of the inboard blades. This would set the outboard blades straight leaving equidistant room on both sides for the blades to hunt in their journey around the swash plate. I have yet to see a change from that set up. As for the dampers, a lot can be said about them especially when assembling new dampers into their retainers. Not sure if a fix has come about, but we were actually removing material from the threaded ends to get the blades to align straight without the threaded portion digging into the ourboard blades at the fork. I would highly recommend during your preflight to check the dampers for delamination as this is the cause for the brantly's infamous "dutch roll." I hope that helps.

Are you back home?

Hey let me get your thoughts on an idea I tried on the dampers.

My dutch roll totally went away when it's cold outside. (Below say 40 degF)

That tells me the dampers need to be slightly harder durometer.

Well to have the same net effect here's what I did ... I made (3 each) 0.032" thick washers the same O.D. as the dampers and placed them inside the aluminum housing where the dampers go, so that when you compress the damper, put the c-clip in, and release the compression, the damper is 0.032" more compressed than it was without the shim washer. Then I readjusted the lead-lag with the rows of rivets like you said.

Wha-Lla!!! No more Dutch Roll even when it's warm outside.

Bryan
P.S. If you'r still over there...thanks for all y'all are doing and stay safe!

When my machine was purchased (750hrsTT) it had a dutch roll. Only over 8o mph and worse at max wt and temp over 20 degrees C. Also we found out board blades were rigged 1/4 in forward. H269C experts say leading is no no, lag is ok.

Anyway we replaced dampers (2 were separated) leaving 1/4" lead. After 20 hrs we had to replace a badly cracked blade. Cracks appeared to originate at damper attachment.
We have had considerable discussion with Brantly inc.

Cracked blade was replaced with 800 hr blade from UK and rigged straight.
After a further 20 hrs dutch roll returned(not as bad) with damper on replaced blade separating. This has been replaced in mean time with old unsepaparated damper. Tried a flight with 1/8 lag - no noticeable difference.

Brantly inc have now issued a service letter about blade alighnment and have a draft service letter about damper installation.

I have a concern that the attachment bolt through damper yolk and blade clamps the yold into blade and may be working into skin. Origin of cracks?

In the mean time first 50hr check showed everything else Ok and we continue to fly. We have also put on a sound moderator and trim on cyclic -what a difference.