RE: Hacker XL Maintenance
Kjell
The front motor bearing (gearbox end) seems to wear the most. Usually noticeable by a change in sound before damage occurs - obvious by noise / roughness when spinning the motor with the gearbox removed. I tried a sealed / grease filled ceramic bearing (rated @ 50% higher rpm than original) and it became noisey around 60 flights. Now back to using the stock bearing and agree that your observation of 300 or so flights is about its life. The end opposite the gearbox seems to last much longer but, as they're relatively low cost (about $6 ea.) it's best to change both.
The propshaft bearings appear to last at least 3X the life of the motor bearings if they are not exposed to solvent when cleaning the gears.
The early fans didn't have the phenolic disc glued to the blades, newer ones have the disc which makes the fan more efficient. However, I've seen several of the discs disintegrate with imbalance / debris doing damage. I fly in high summer temps and find the fan without the disc to provide adequate cooling if attention is paid to airflow to the motor.