This was my evening with the 6hv re maiden, didn't go so well

[LubeMan1]

[Mattinfla]

Ouch. Condolences.

[Rob43]

Sorry. What happened?

[LubeMan1]

Originally Posted by Rob43

Sorry. What happened?

I'm not sure really, I had to replace both swash to grip links cause I broke one last Thursday after a bad spool down shake( which I think is common on the 6HV). Parts came in today and everything was installed.

So tonight I went out and spooled up for the first flight and noticed a little tail twitch, now earlier I had increased my tail gain 10 points because I was getting some tail blow out in full negative collective tail down hurricanes, so I thought I had went to high and was getting wag in a hover.

I landed and dropped the gain down 5 points and lifted off again, everything seems better, so I did some clockwise piros but when I let off the rudder it shutter a little then started to Piro our of control.

I tried to save it but it happened so fast and was only about 10 feet off the ground it started to get out of shape so TH then "whack" it was down.

The carnage you've seem, one interesting note though was the rudder servo lead was unplugged when I go it back to the bench, but not sure if that happened before or after the impact.

Assessment of actual damage tomorrow. I don't think it's to bad but I'm pissed that one of the new link I put one snapped off!!

Damn It!! Lol

[mrbubbs]

You mentioned your tail wagged then piro uncontrolled. My vote is tail servo bad or became unplugged. As you crashed, tough to say whether the tail servo became unplugged due to impact, but I would still do some bench testing to make sure the servo is good. Make sure it's not twitching. Put a small load on the servo horn with your finger while you run it to make sure it's maintaining torque throughout its range. Check the servo temp to make sure it's not overheating. Make sure it's still centering well. With it unpowered, run the servo horn back and forth slowly to make sure no teeth are missing.

If they are still present after the crash, check your tail linkages to make sure they aren't too worn, possibly popping off in flight.

As for the spool down shake, others have suggested raising the head by using the lower bolt hole in the head. I would recommend checking/relubing the dampers/feathering shaft/thrust bearings. Or go with softer dampers.

However, I have the original 6HV too and run the harder lime green KBDD dampers. Like you, I have the head mounted at the lowest height. I just make sure to really lather some synthetic grease on the dampers and internal head assembly. Never any shakes for me.

Maybe lower your rotorhead/cyclic gain to make sure it's not borderline too high that shows up with shakes amongst ground resonance.

I also land with TH, 0 pitch, and float the heli down. I think landing with too much negative under power causes odd shakes/resonances. I've seen it bad enough with a friend's 700N and BeastX that the heli flipped and landed on its head button. That was after he had already landed and was spooling down. I recommended he use TH and float it down. No problems since!

Nice canopy. I need to do that slant gear mod. Still running straight cut but it hasn't given out on me (yet!)

[LubeMan1]

So I finally tore it down and found that all I need to replace are blades, tail shaft, boom and boom supports. I was able to straighten the tail rod out, now that was still connected to the tail slider but was disconnected from the tail servo, but I think that may have happened from the impact and boom strike.

The tail servo moves smoothly no notchyness or binding and the horn is good, but what makes me scratch my head is that tail servo being unplugged.

So I started to think about that last night and the only explanation I could come up with is that this is the most likely culprit and this is why: I'm running a Spirit FBL unit on here and earlier in the day I had made some computer adjustments with the USB connection....well that connection plugs into the FBL unit RIGHT NEXT TO the rudder servo input and its a pretty tight fit between the servo connector and the side of the unit case.

I think maybe when I removed the USB connection I may have inadvertently loosed the rudder connection and didn't realize it and when I went fully throw piro to test the tail the spinning force maybe threw the lead out the rest of the way?

That's all I can think of until I get it back together and test the servo under power.

All parts should be here tomorrow.

[LubeMan1]

" I have the original 6HV too and run the harder lime green KBDD dampers"

I also took the head apart and found that I indeed too had the lime green dampeners, I took them out and replaced with stock ones because I couldn't, no matter what I tried, get the grips to move smoothly/freely. They wouldn't fall under their own weight and felt notchy.

With the stocks they were smooth as silk. I re-greased everything too.

[Ah Clem]

On the servo connectors-tape them in with a strip of double-sided foam tape along the edge of the case, or use hot glue to keep them in.

Connectors coming loose can happen on any brand of FBL unit or receiver. There used to be quite a few threads on HF about connectors coming out.

I have used the Lime Green and Royal Blue KBDD Dampers in the original 6HV/TracX heads with no issues. Almost invariably, they will initially not be smooth when you assemble them. After about five flights they loosen up. Same with the older Trex 700 heads and several others.

Do whatever works best for you, but it is, IMHO, worth it to have the better dampers (KBDD) with the increased flapping range than the stock ones (I have flown both, over the years). Make sure that the KBDD Dampers are lubed thoroughly, inside and out, with silicone grease (not soap).

[Mon_t]

I didn't have any luck at all with the lime greens. Had that really bad spool down shake where it would spit the links (using ptfe grease).
After going back to the stock dampers it worked perfect.

Not long ago I put in a set of royal blue kbdds lubed them up with silicone spray, rather than oil or grease and everything seems to be smooth.
They've been working great so far for the last few months, so I'd definitely go for those rather than the lime greens.

[LubeMan1]

Good to know Mon_t, maybe I'll order up some blues!

[Ah Clem]

The shake on spool down and the notchiness are actually two different issues.

As mentioned before, the notchiness goes away after a few flights.

The tendency to shake on spool down can be addressed in three different ways:

1) Using softer dampers (i.e. the Royal Blues)
2) Raising the head about 5mm (using the lower bolt hole in the head block and TracX drive tubes, which are 5mm longer). Dave Kettlehut came up with this approach.
3) Using lighter main rotor blades.

I have had no issues with the shake on spool down after raising the head 5mm when using the Lime Green Dampers and stock Compass main rotor blades. I did some testing of heavier blades a few years ago, and the shake on spool down returned (the blades were the only change). When I re-installed the stock Compass main blades, I had no issue.

[Rob43]

Interesting...I had not previously heard of the blade weight relationship. Mine did it the first couple of flights. I raised to the lower bolt hole, and flew it a while that way. I later disassembled the main rotor after a minor incident, and when I reassembled it, greased the dampers liberally, and re-installed at the lower location (upper hole). The shakes were gone.

[LubeMan1]

"Sigh"

After meticulously setting up the head "fixing" the head dampener situation and installing the new tail parts I finally took her out yesterday to re-maiden and I forgot 1 "minor" detail...

I'll let you figure it out.

"Sigh"

[ARM_Coder]

Originally Posted by LubeMan1

"Sigh"

After meticulously setting up the head "fixing" the head dampener situation and installing the new tail parts I finally took her out yesterday to re-maiden and I forgot 1 "minor" detail...

I'll let you figure it out.

"Sigh"

Attachment 597327

I once left the mast collar a bit loose in my classic 6HV, but not THAT loose!

Edit: you most likely need a new belt too.

[Mon_t]

Doh.

[LubeMan1]

Originally Posted by Mon_t

Doh.

Yep found it laying on the tail belt gear.....

[LubeMan1]

I figured out why I lost the tail previously, the tail gear lost the roll pin that pinned it to the shaft leaving it free to spin on the shaft under load.

It must have been thrown out while in test hover (that could have been the twitch I got right before it went out of control).

Maybe it just worn out.

[Ah Clem]

I don't know if the pin had been removed for service, but it is a really good idea NEVER to use the same roll-pin twice.

I have seen re-used ones break and come out, both on our helicopters and in automotive use.

[LubeMan1]

Nope, I had to remove it to change the tail shaft AFTER the crash, but pretty sure not before. Although I did buy this stuff used so who knows about that.

[LubeMan1]

So tonight I flew and after all the work and fixes just to really find out the align ds550 servo is taking a s**t. Help me choose a better tail servo, I'm done with align.