Service difficulty report · Surpercharger · Dhav DHC2MK1

Difficulty date
October 23, 1996
Submitted
March 26, 2000
Operation
General aviation
Make and model
Dhav DHC2MK1
Engine
Pwa R985AN14B
Part
Surpercharger
Condition
Failed Bushing
Location
Impeller Shaft
Stage of operation
TX
Nature of condition
O
Precautionary procedure
E

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

What was found

(CAN) ENGINE SUPERCHARGER PRESSURE FLUCTUATING AND MAKING A HIGH PITCH SOUND. NO METAL WAS FOUND IN THE OIL SCREEN. INSPECTION FOUND THE IMPELLER WITH EXCESSIVE MOVEMENT. ON DISASSEMBLY THE EXCESSIVE IMPELLER MOVEMENT WAS CAUSED BY THE FAILURE OF THE SUPERCHARGER SHAFT BUSHING, BECAUSE OF AN UNAPPROVED REPAIR TO THE OIL FEED GALLERY PLUG THREADS WITH SOME TYPE OF COMPOUND WITH A FIBEROUS TEXTURE. THIS SAME COMPOUND WAS FOUND CLOGGING THE OIL PORT TO THE BUSHING. WHEN THE BUSHING SEIZED TO THE SHAFT TWO TEETH WERE SNAPPED OFF THE FLOATING GEAR DRIVE.