Loose fitting head dampers

[nu66ie]

After about 10 flights on my Trekker I noticed some play developing in the head. Upon inspections I found the dampers were very loose fitting. They practically fell out of the main rotor housing and would slide right off the feathering spindle. When I built the heli they felt tight. I put in a new set and all seems to be good again. Has anyone else noticed play developing in the 800e head?

[hadi10]

today was my 6th flight with the trekker with some light 3d.. and still good

[nu66ie]

After trying to get the slop out of the grips, I finally took a big swing and replaced the the feathering spindle and the parts that move with it. A few days ago I noticed a little wobble as the heli would spool up. (The wobble was never there when the grips were tight) Now that the play is gone, the wobble is gone as well.

I went through three sets of dampers in about 40 flights. They would press firmly into the main rotor housing when installed and after the play got bad enough and I took it apart, they would slide right out of the main rotor housing with very little pressure, and slide right off the feathering spindle.

When I slide the loose (worn) dampers that came out of the 800e into the main rotor housing of my 700e, they fit in with very little pressure. Nowhere near the pressure needed to press in a new set.

I have put eight flights on it since I replaced the items and it seems OK, Although I don't have allot of confidence that the problem won't show up again.

Can someone who has had +20 flights check theirs to see if there is any play? Grab the grips and rock them side to side. You can see the play where the feathering spindle leaves the main rotor housing.

[martin_]

This is another disadvantage of the DFC style head, not only the link does not flex, but when force is applied the rigid link want to push/pull the feathering shaft in its axis.

I have numerous flight on my 700 and there is no sign of play, but the head maybee undersized for 800 blade.

Can you put some shim to stiffen things a little? This is what I would do.

[hidaven]

This is NONSENSE! They rushed this 800 out and its not able to withstand the stress using 700 sized parts! The logo 800 is a solid 800 size and they used a lot of its parts for the 700. Stupid Align did the reverse! The OWB block is garbage and now it looks like we need a KDE head upgrade as well! Shame on Align. My guess is that we need stiffer dampners using a less compressable material. I hope the blade grips are solid enough to hold these big 800mm blades in place...............

[nu66ie]

Your right!... It would be nice if Align would chime in and give up some information. I never really liked being a beta tester, especially with a flying guillotine. Surely if Align's test pilots put a few dozen test flights on the 800s, some of these issues would have surfaced.

The blade grips are plenty strong but there is apparently some things in the drive train that may not be up to the loads of the 800mm blades. Some speculated on this when the 800 was announced as a 3D bird.

After the upgrades and parts I've replaced, the heli seems pretty solid, finally...I read somewhere that the Align 790mm blades may give the power train some relief with minimal effect on performance. Again, it's all hearsay.

[hidaven]

Anyone make the stiff dfc dampners aftermarket? How exactly do you tell if they loosened, flex the blade grips up and down on each side? Someone has to make an aftermarket solid dampners as the dfc 700 has been out awhile.......

[nu66ie]

Turn the blades 90 degrees to the boom, grab the blade grips and rock them side to side. A very small amount of play is OK but if you can hear it rocking, something is not right.

Take your blades and main grips off and look at the damper, Are they tight in the main rotor housing or do they fall out? Will the feathering spindle slide through when you turn the rotor housing on it's side? Look at the spindle spacers, are they tight on the center of the feathering spindle?

[hidaven]

Thanks Don, any aftermarket companies making stiff replacement dampners? The trueblood green ones seem to ba a good match

https://www.helifreak.com/showthread.php?t=432314

[nu66ie]

I have a set of lime green trueblood dampers I took out of a customers crashed heli and they do not feel as rigid as the DFC dampers. I'm not sure of the part number but they are lime green. Some of the 700 guys really like them but we are back to the ?'s about the loads of 800mm blades swinging ±11° of pitch at 1950rpm.

I really don't have allot of experience with aftermarket dampers. I know that a harder damper will make for a nervous heli at lower headspeeds and a soft or worn damper at higher headspeed can cause unwanted effects, like cyclic bounce on hard stops, which I noticed on mine.

After replacing those spindle parts, (18 flights) it's been pretty solid with a very small amount of play. It had no play after the new parts were installed. Heck, maybe the main rotor housings used on the 800e's are out of spec.

I'd rather have to replace dampers every so often than OWB failures.