Thanks Tommy, we need all the honest info we can get in this
game.
Perry Mick asked:
If there was a restriction in the oil line going to the drive, such that
the
drive "saw" a low oil pressure, could that cause something like this?
Just a
thought...
I doubt it, the allowable range of oil pressure at the drive is pretty
wide, about 25 - 100 psi. Even a momentary drop to zero would not be
catastrophic.
Tracy
----- Original Message -----
Thanks T,
An honest man may be
hard to find, but appreciated by all who know him.
Tommy<><
Subject: [FlyRotary] Re: Post Mortem on
Steve Brooks RD-1B
Total time on
drive was 20 hours. Steve noticed the problem as an oil leak from
the input shaft oil seal. Internal inspection showed the input
shaft thrust bearing roller cage which is a polymer cage to be partially
melted and most of the rollers were out of the cage. Overheat was the
obvious cause of cage failure. Rear race of bearing was seized on input
shaft and was 'blued' from heat. This allowed the shaft to move back and
contact the adapter plate. All sorts of nastiness resulted from this but
the details are not as important as the root cause. Amazingly, the drive
continued to operate normally but the time between roller cage failure and
discovery of the problem is unknown.
The oil passage
from the input shaft pilot bearing to the thrust bearing was found to be
clogged and no oil was getting to the thrust bearing (except for incidental
splash). What caused the clog has not been determined. I will
attempt to carefully grind away the input gear and see what it was as time
permits.
The rear race was
spinning against the adapter plate and acting as the thrust bearing while
being lubricated only with splash. That Mobile 1 is amazing
stuff!
A careful
inspection of the gears showed no evidence of damage or
wear.
Corrective
action: Replaced the input shaft assembly and thrust bearing,
installed nylon snubber/spacer to bring input shaft endplay into
spec.