balancing act

Claude: The free wheel idea is possible, I don't think that I got the sprag
loose every time, but I know I did several times. I have done three Safaris
and was able to quite easily take them down to 0.05 ips in no more than 4
starts and mine was one of them. However something has changed. I'm in the
process of replacing all the plugs to see if there might be an intermittent
plug causing an additional vibration that I felt while checking engine
vibrations with the balancer. # 4 plugs both look like that cyl is running
quite rich. The engine ips did not repeat well but the ips was down below
0.2. I disconnected the tail rotor shaft at the orange coupling or the
exit of the main transmission. I did check the DSS on the bench and it does
appear to function properly.
Compression check is next after the plugs are replaced.


--
Kathryn Fields
Experimental Helo magazine
P. O. Box 1585
Inyokern, CA 93527
(760) 377-4478 ph
(760) 408-9747 publication cell
"claude lescure" wrote in message
...
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