Premature wear of the gear boxes

gearbox rotax 9 eprops

Premature wear of the gear box, which can generate vibrations, up to breaking point ? To to ensure the longevity of your gear box, carefully check the weigths and the moment of inertia of your propellers.

A too heavy propeller with a too high moment of inertia is really dangereous for the Rotax series 9 gear box .  Some variable pitch propellers weight up to 17 kg; in this case, the gear box of the Rotax serie 9 have a lifetime lower than 400 hours. But even a 6 kg propeller might cause problems to the reducer.

gearbox rotax 9 epropsThe maximum moment of inertia of the Rotax serie 9 is 6.000 kg.cm². It is very important to comply with this moment of inertia. Some information on the MOI :

The E-PROPS propellers for ROTAX serie 9 are the world’s lightest, and have their MOI between 1.800 and 4.000 kg.cm², depending on the models.

To go further, an article from Jérémie Buiatti on the propellers inertia (in French)  :