Astar Main Rotor Balancing

[IFlySometime]

Looking for some tips to get a good main rotor balance on the Astar. My experience level on them is low but im rapidly fighting the wolves. 
We use the microvibe and using its instructions along with airbus you first setup ground track and take out ground lateral vibrations. Easy enough. Then hover track and hover lateral. Also easy however my issue is that hover balance is nice and smooth the ground track and balance  is no longer smooth. Normal or am I missing a step? 

When bending tabs, if you need 3 degrees tab on one blade do you bend both tabs 3 degrees or do you split it and either bend one 3 degrees or both 1.5 degrees? 
 

One more... on descent, it has a real nice three per rev vibe. Only noticeable in descent. I’ve checked everything recommended for three per revs. Had it on jacks and checked the gear etc. Hammers? Its a B3e with post mod hammers. With the washers. I tried removing some washers but was hard to say if it got worse or better. 

 

[ray]

When you take the ground reading and then hover, get the hover smooth and disregard the ground. The ground reading is in case it is way too rough to pull into a hover. You still have to read it every run, because it's a process built in.

Split the tab readings between the 2 inboard tabs as evenly as you can.

Hammering on descent: Check the swashplate friction.

B3e has variable Nr, so the hammers change frequency with rpm. Restore the weights back to what they were. Change weights only with the Airbus hammer tuning device.

[DGP]

Not sure what equipment you are using...but I did most of the balance flying on 407 with Rads...we usually had the Bell rep bring in the gear...he would take the readings and I would do the adjustments...on 407 there is a let down reading which was hard to get...you had to have lots of altitude and then at least 1000fpm descent...there were adjustments to get rid of high readings on that as well...not sure about Astar.

[Superwrench]

Your ground is no longer smooth? Has your track changed much from hover?  If ground is not smooth, (0.35ips is limit on high gear) check your shocks are good, may need fluid added. 

 

For the three per, what is your ips at( on the one per)?  Common 3 per issues are windshield screws, check there torque. 

Also if your one per ips reading is below 0.05, not uncommon to start to feel normal 3 per that is always there.  I have had smooth readings on balance gear, but you feel the 3 per.  Actually made the machine a little ruffer, so it felt better.

 

If you are using a microcibe there is a procedure at adjust hammers.  Personally I have only adjust hammers 1 or 2 times in 15years.  If hammers are out I notice pilot or co-pilot seat would feel different in flight, and if you put you feet on the floor in front of your seat, you can feel the hammers. 

 

Just my thoughts.

 

Hope that helps

[R0T0R]

It helps to have the right colours in the right place too. A few years ago we came in after a weekend away and a fresh engineer and lowtimer had spent the whole weekend with no success. Turn out the blue blade was in the wrong position. 

[DGP]

As SuperWrench said...if you get things too smooth you will feel other vibs...works with all helicopters..2...3...4...blades....I notice it more in a 2 bladed ship...if the hover balance is below .2 you with notice the 2 per hump more in flight...same with 4 blades...4 per....never did much balancing on 3 blades. On 4 blade you should stop trying so hard when you are down to .1 ips. The Bell rep once got the 407 down to close to .1 at 140 knots...only once...man was that nice to fly!

[Superwrench]

8 hours ago, R0T0R said:

It helps to have the right colours in the right place too. A few years ago we came in after a weekend away and a fresh engineer and lowtimer had spent the whole weekend with no success. Turn out the blue blade was in the wrong position. 

I have had a similar experience.  The mag pick up interrupter was on the wrong spot on the swashplate.  The interrupter should be over the mag pickup with the red blade over the nose.  Made all my move lines 120degrees out.  Took a few runs to figure that one out.

[IFlySometime]

6 hours ago, DGP said:

As SuperWrench said...if you get things too smooth you will feel other vibs...works with all helicopters..2...3...4...blades....I notice it more in a 2 bladed ship...if the hover balance is below .2 you with notice the 2 per hump more in flight...same with 4 blades...4 per....never did much balancing on 3 blades. On 4 blade you should stop trying so hard when you are down to .1 ips. The Bell rep once got the 407 down to close to .1 at 140 knots...only once...man was that nice to fly!

Thanks for all the info guys. Much appreciated. So this definitely happened, a bit by accident though. The heli had a bit of a hump, we just got our brand new Microvibe and I was more than thrilled to burn that old chadwick....anyway. Only two runs later it's butter smooth, almost scary smooth. Then we descend back to camp and the 3per is there. I ask the pilot, has that always been doing that? Answer was, "I dunno"  

I've check over the usual 3 per culprits, it's been through a 600 and I'm pretty sure the swashplate friction was fine but I may just have another peak at that. If that's fine might just be that it's too smooth it was showing under .2 hover and MCP straight and level was around .1. lt's really nice, other than on descent. The starflex ball bearings were worn and I hoped that new ones would fix the 3per. No luck.

As SuperWrench also mentioned the shocks. I did have those off and did the pull test as best I could, they seemed nice and tight. The leafs are deflected a fair bit and have some on order now. It has a decent wobble on the ground at flight idle. Tail rotor is nice and smooth. It was a windy day and the tail was pointed into the wind at the time, so that might of caused some of the wobble.

[rotorotor]

Rough on the ground... have a look at the bi-directional crossbeam pucks. If they are soft or losing torque? Signs of fretting. Maybe could translate into the M/R when the disc isn't loaded up if it isn't supported properly.

[DGP]

We were tracking a 206 one time and the wrench with me just wouldn't give up...he had the ground and hover down to less than .1...inflight was just over .2...he finally gets it to .1 in flight and I told him it felt worse...after we parted ways I decreased the tab on one blade 1 degree ...felt great at all speed!