ORIGINAL: jeff naul
hey guys i have jj-1400. twice its been back for bearings going out, it always happens on the third flight, i get it back and once again third flight bearings start making noise. first set was on klotz r-50 synthetic oil. second time was on shell turbine oil
third time alysyn aerospace oil. it has had the larger tail cone since the first trip in for repair
any ideas?
I agree with Smithy that your rear bearing failure is most likely down to lack of lubrication reaching the rear bearing (which resides in the very hottest zone). Consider all fuel is dirty from being in the commercial storage tanks with rust and dirt. The bearing lube line has the smallest opening and restriction, even smaller than the 12 fuel injectors and can be blocked in an instant from unfiltered fuel. So as a guide filter the fuel into the main tank, use a filter on the main tank clunk, use a header tank with a filter and then a 'last resort' filter after the pump to collect the gear rubbings. This last filter should in theory be found to contain nothing and be free flowing after a full season of flying.
If its going to back to Gabe ask him to re check the 'flow rate' on the lube line as three flights per bearing indicates the above situation or a major imbalance that would also cause a bearing failure.
Paul
Paul