Report of blower impeller rubbing with housing and excessive axial/radial play.
Caused by failed 47-146-1 bearing (total time unknown).
Bearings replaced, blower assy inspected and returned to service.
Approx 150 hrs later, shaft sheared.
Most probable cause for shaft failure; stress fatigue.
Even though the shaft did not show any evidence of visual damage at inspection, it should have been replaced.
Material fatigue subsequent to overload or stress is generally not detectable by NDI methods.
AS A REMINDER
BHT Maintenance Manual Special Inspection at 1000 hours.
Disassemble, clean, inspect and to avoid unscheduled down time, replace bearings.
Bearings are non-greasable type.
Refer to Vendor CMM (BHT-412-CR&O-V.2)
Occasional reports of bearing liners wear or liner coming out of housing bore at bearing replacement.
Liners are not field replaceable.
Machined for concentricity and perpendicularity after installation.