Thanks and noted Peter...
After spending an entire lifetime pulling stuff apart and analysing cause and
effect
of mechanical component failure i'm totally unconvinced on this argument
often presented, simply because the propeller is operating within a state of
constant load resistance leaving both the drive and driven gears no opportunity
for backlash while in this state; if there was backlash occurring that would
be a serious design concern and source of vibration; at my level of experience
my ears and bum would let me know as soon as this occurs, and neither have yet
told me otherwise (not in this individual aircraft; can't say the same for
some other 912 units flown in)... the output shaft is also operating in a state
of harmonic balance thanks to the fitted Balance Master... the carburettor
mixtures
and carburettors are in perfect balance... the engine is a low compression
setup... there is no aspect about the power-plant's current operational spectrum
that gives any credibility to the debate... If the engine is not singing
then its out of tune, set at the wrong rpm frequency, or both... under constant
load there are a limited number of factors that can cause gear failure -
insufficient fit-for-purpose material specification, sustained overheating
beyond
safe operating temperature range and allowable time of said material, sustained
mechanical vibration at specific alternate frequencies, excessive mechanical
impact of sliding contact surfaces due to backlash (there will always be
an element of backlash required for component heat expansion), ingress of
foreign
matter such as swarf other particles dust sand etc.
It is not expected many people in any mechanical field will share my experience,
and am still often left amazed but accepting at what level of damage the
majority
of human beings can achieve... could fill a text book with field stories,
but thats about all I have to say on the matter today.
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