balancing act

Stu,
If I understand, the figures in term of IPS and angle does not repeat each
time you decrease to idle and start again.I may be incorrect but each time
you are passing though idle the engine crankwheel can take a different place
due to freewheel. And the vibrations from engine(same speed than tail rotor)
could mix, interfer or be added and amplified with the tail rotor
assembly.The different place taken by the engine crankwheel and slip between
engine and rotor shaft each time you reduce the throtle could be the
answer for non repeatable reading .
Have you tried to put a velocimeter on the engine itself to see the level of
vibrations at 2700RPM?
Where did you disconnect the tail rotor drive? is it on the mainrotor side
or on the tail rotor side?
First try to check your DSS on a bench.I am almost sure that it is ok as
the figures are constant as you go from 2500 to 2700 except IPS slight
increasing. You could as well make a try with the second velocemeter.
About tracking influence on vibration I can assure that on main rotor
track adjustment has mainly effect on vertical vibration but have as well a
great effect on lateral vibration. And it should be the same on tail rotor.
Last time I balanced my tail rotor I had difficulties to get below 0.2 IPS.
I am sure you will succeed.
Claude
"Gary Knutson" a écrit dans le message de news:
Tv6fg.98088$iU2.89247@fed1read01...


claude lescure wrote:

Stu ,
I was just thinking: maybe the problem is comming from your balancer.

Along those lines, Chadwick-Helmuth makes (or used to make) a calibrator
for the purpose of check the balancing equipment. It was a fairly simple
device and probably could be duplicated (as the Chadwick version was
pricey). After chasing the T/R balance on my 269, it turned out the
problem was indeed the CH balancer. It was not an obvous problem.

I looked online and noticed that CH had been purchased by Honeywell and I
wasn't able to find any further info.

Gary