Service difficulty report · Bearing · Saab SF340A

Difficulty date
April 18, 2012
Submitted
September 14, 2015
Operation
General aviation
Make and model
Saab SF340A
Aircraft time
46,272 hours
Engine
Ge CT75A2
Propeller
Rotol R3894123F25
Part
Bearing
Part number
MS276415
Condition
Failed
Location
Ailerons
Stage of operation
IN
How discovered
9
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

(CAN) DURING HEAVY INSPECTION, WITH THE AILERON CABLE TENSION SLACKED OFF, IT WAS NOTICED THAT THE RT AILERON BELLCRANK, IN THE WING, MOVEMENT WAS ROUGH AND NOISY. UPON REMOVAL FOR FURTHER INSPECTION, IT WAS DISCOVERED THAT THE 2 BEARINGS, PN MS27641-5 THAT SUPPORT THE BELLCRANK WERE COMPLETELY DISSINTEGRATED. SEVERAL BALL BEARINGS WERE MISSING ENTIRELY, THE AILERON BELLCRANK WAS NO LONGER SUPPORTED BY THE BEARINGS, BUT RATHER BY THE THROUGH BOLT THAT ATTACHES THE BELLCRANK TO THE WING, THIS CAUSED SUBSTANTIAL INTERNAL DAMAGE TO THE BELLCRANK. THE BELLCRANK, THRU-BOLT AND 2 ATTACH BEARING NEEDED TO BE REPLACED. IT APPEARS THIS FAILURE IS DUE TO LACK OF LUBRICATION. ON THE OTHER MODELTHERE IS A GREASE FITTING ON THE BELLCRANK ITSELF, ALLOWING PERIODIC GREASING OF THESE BEARINGS. THIS ACFT DOES NOT HAVE THIS MODIFICATION AND THE BELLCRANK MUST BE REMOVED TO BE GREASED. NOTE: DUE TO THE HIGH CABLE TENSIONS, AND DESIGN OF THE SYS- IT IS NOT POSSIBLE TO NOTICE ANY ABNORMALITY OR ROUGH MOVEMENT OF THE BELLCRANK UNTIL THE CABLE TENSION IS REMOVED FROM THE SYSTEM.

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