H500 Vibe
 

I have changed quite a few components in an attempt to get rid of a vibration in the airframe mainly felt in the pedals as forward flight increases in my 500D. when I balance tail with or without Vertical on I can get it down to a very low range (.03 ips) . at idle there is a slight rumble and a come and go vibration, when at a hover things go away unless there is gusty wind, then in forward flight the buzz gets worse as airspeed increases. The head has 400 hrs on it and I have noticed that the striker have gotten excessive wear on them . ( just a note I have over 20,000 hrs in the 500 and I am the only pilot and religiously keep cyclic center when on ground in idle). I have replaced TR driveshaft, TR Blades and Clutch. When I installed the head it Was very Stiff and jumped a lot at idle and quickly wore the striker, just replaced then recently and the stick vib at idle is gone for now but the Tail pedal start a Vib with speed and I can sort of feel it throughout airframe. Any help from you guys would be greatly appreciated.

H500, has this vibration been present since you got this equipment or did it develop after something was changed due lifecycle replacement or the part failed?

Striker plates shoudn't wear unless the static droop angle is too high. Which can also give you cyclic feedback.

The washers under the bearing housing to the pitch housing- I guess you have measured it. Someone experienced with a 5 can tell by just looking.

Otherwise if you have weird vibes and have tried all the usual suspects have a look at the undercarriage for loose or worn bearings/bolts, especially inboard, or someone has left the topping spring out of a damper!!

Vibe
 

Try changing the drag link on the swashplate. Had a similar weird vibration once, and that was the cause...

What frequency is the vibration? High, medium, low?

What have you changed, inspected or messed with to identify the vibe? When did it start? What happened prior to that?

We rebuilt the aircraft. All parts on the head new or overhauled except Mast. buzz came with speed from the beginning.

From the start after refurbishment

what is a topping spring?

changed the drag link ( no effect)

high, to medium high, I have changed clutch, aligned engine, checked damper to 2 lbs, check drive shaft shimming, changed TR driveshaft, changed TR Blades, looked closely at TR Fork and doesn't seem to have damage but its old, had to replace striker plates already and I am only one flying, Changed TR swashplate , changed TR Feather bearings ( noticed more wear on one set than the other ) . Changed TR PC Links, noticed head was real tight and required lots of cleaning and lube to keep it from squeaking, Swashplate is overhauled but has not been changed yet ( I believe it may be suspect), all Mixer bearings were replaced at Refurb, I am thinking maybe TR Fork, Swashplate or possibly Droop angle ( it looks to me like the blades are standing up slightly more than I am used to)

Had exactly the same on one of mine, tried everything, turned out to be the bearing that holds the front leg to the keel. In the hover no problem as we accelerated the skid would vibrate on the bearing causing a horrible buzz ! Changed the bearing problem went away. We had tried everything before including changing the whole drive train !
Good luck. The way to check, lift the helicopter off the ground on a hoist, grab each skid and see what happens

Considering you've already spent a good deal of time/money, you may want to rig up some vib equipment and chase it that way. Knowing the vib freq or its multiple goes a long way to finding it. I chased one vib in a 206B that ended up being a worn bearing in the ST/GEN that was felt in the door posts and thought to have been T/R related. After multiple sets of blades, G/Bs, and shafts we vib probed the engine and found it but only as a multiple of the T/R drive 6000 rpm with the engine ST drive gear turning 12k rpm. Even tech support was shaking their head. Hopefully it will be something simple like the gear as mentioned above.

noticed you have not changed out swash. once had a high freq vibration in a 500 in fwd flight- not in any other part of flight envelope. we were not able to find it after much investigation and time spent. swashplate (bearing- perhaps not the correct technical name) came apart in flight.
https://cimg1.ibsrv.net/gimg/pprune....ed38cd5300.jpg

Hey Wrench, not to hijack the thread but, how long ago was that - mid 80's per chance?

That sounds about right.

If it was painted red/ white/ black, I'm on my way to buy lottery tickets.

Ha. No. Yellow was the base color. But without derailing this thread any further, if you flew those colors then still buy those lottery tickets since you must be lucky considering what I saw when one of "those" aircraft visited offshore... or the stories I heard...:eek:

Worth a look at the Main rotor pitch change/flapping bearing.
If the teflon lining wears out the bearing starts to wear into the pin.
Shows up as a vibration and when tracking the targets move in and out of track.
Easy to check. Take of the blade hold the cuff horizontally and try to move vertically (not flapping)
Should not move or clunk!!
I have seen this on relatively low time heads.

Bit like this thenhttps://cimg3.ibsrv.net/gimg/pprune....2ba63282ae.jpg

Try and chase down Neil Laing in New Zealand.