Service difficulty report · Crankcase · Cessna U206F

Difficulty date
August 24, 2004
Submitted
November 2, 2004
Operation
General aviation
Make and model
Cessna U206F
Aircraft time
7,692 hours
Engine
Cont IO520F
Propeller
Hartzl PHCJ3YF1
Part
Crankcase
Part number
654101A7R
Condition
Unserviceable
Location
Engine
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) CRANKCASE FAILURE (7TH STUD CRANKCASE) INSP WAS CARRIED OUT. CYLS NR1, NR3 WERE REMOVED SO NR2, NR3 INTERMEDIATE BRG SADDLE COULD BE VIEWED. MOVEMENT OF BRGS HAD OCCURRED, TEAR DOWN WOULD BE REQUIRED FOR FURTHER INVEST. IT WAS FOUND THAT THERE WAS FRETTING OF CRANKCASE ON NR2, NR3 INTERM MAIN BRG THRU-BOLT PADS. PINCH FIT IS LOST ON MAIN BRGS IN THESE POSITIONS, BECOME LOOSE. BRGS ON BOTH SIDES OF CRANKCASE WERE MOVING IN NR2, NR3 INTERM BRG POSITIONS. BRG IS ABLE TO MOVE BACK AND FORTH IN BRG SADDLE (NOT ROTATIONAL). OPER WOULD HAVE ALLOWED INCREASED MOVEMENT OF BRG, BLOCKING OR RESTRICTING OIL FEED GALLERY IN SADDLE AND CAUSE OIL STARVATION. THIS WOULD LEAD TO CATASTROPHIC FAILURE.

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