Rotax 912 Series Maintenance Manual page 115

Effectivity 912/914 Series
Edition 1 / Rev. 0
BRP-Rotax
Maintenance Manual
Advanced pitting:
See Figs. 72-47 and 72-48.
Characteristics:
Larger areas of breakoff, normally appearing as pitting zones. The
breakoff surface usually has a shelllike structure. The total pitting zone
may reach a size where it impairs smooth engine running noticeably or
the remaining flank surface wears rapidly and is destroyed.
Causes:
The pitting can be attributed to material fatigue due to a combination
of the mechanical load factors pressure and friction. It is triggered by
exceeding the material to excess loads at certain points. Decisive
factors for the formation of pitting are: Oil viscosity and oil temperature.
Conclusion:
Pitting of up to approx. 5 % of the flank surface is permissible if the size
of the pitting (at its widest point) does not exceed 0.5 mm (0.02 in). If
this value is exceeded, the gear set must be replaced!
▲ WARNING: Gears must always be replaced as a set. Replacement
of individual dog gears or drive gears is not permissible.
Pitting in the area of the root
flank of a spur gear.
Fig. 72-47
Magn.: approx. 75%
00151
Pitting formation at the foot of
spur toothing
Fig. 72-48
Magn.: approx. 75%
00152
72-00-00
page 47
May 01/2007