Rotax 912 i Series Maintenance Manual page 152

Rate of development
The rate of development depends on the lubri-
cant and amount of stress. The pitting surface
can become so large that the remaining unda-
maged flank can no longer transfer the load.
During further operation the gear-tooth system is
then completely destroyed.
NOTE: Fine pitting or pitted areas hardly af-
fect the running behaviour of the
gear-tooth system at all.
The rule is however pitting damage which incre-
ases over time.
A distinction can be made according to the size,
type and number of pitting, as follows.
- Slight pitting (initial pitting)
- Destructive pitting
- Flake pitting (large-area flank fractures)
SLIGHT PITTING
Features:
Individual small pits (up to approx. 0.5% of the
flank area) or pore-like areas of pitting, generally
only present in the dedendum area of the flank.
This pit formation can cease during the opera-
ting phase of the gearbox.
Causes:
Locally high stresses in gears which have not yet
run in can result in isolated pits. The adjustable
running-in wear which results in these areas
being relieved of stress, as a result of which the
formation of pits can cease. Similarly, changed
operating conditions can prevent pits which have
already formed from developing.
Conclusion:
These pits are not important for safe operation.
The gear set can still be used.
Effectivity: 912 i Series
Edition 1/Rev. 0
BRP-Powertrain
MAINTENANCE MANUAL
NOTE:
See Fig. 17
Fig. 17
Magnification: approx. 2x
Fig. 18
Magnification: approx. 1.5x
The illustrations are sometimes not
very informative due to fine pitting or
the reproduction process. If in doubt,
consult technical literature or contact
the authorised ROTAX distributor or
its service centre.
to Fig. 19.
72-10-00
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July 01/2012