Service difficulty report · Drive Shaft · Cessna 421C

Difficulty date
April 13, 2001
Submitted
June 13, 2001
Operation
Air carrier
Aircraft
N6794D
Make and model
Cessna 421C
Aircraft serial
421C1030
Engine
Cont GTSIO520L
Part
Drive Shaft
Part number
632799
Condition
Seized
Location
Engine
Part time
1,590 hours
Stage of operation
IN
How discovered
V
Nature of condition
K
Precautionary procedure
K

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

What was found

AT 25 HR OIL CHANGE, INTERVAL OIL WAS FOUND VENTING OUT RIGHT ENGINE OVERBOARD DRAIN AND OIL DRAINED FROM ENGINE HAD METALLIC GLIMMER TO IT, ALTHOUGH CUTTING THE OIL FILTER DID NOT REVEAL ANY UNUSUAL AMOUNT OF METAL. OIL VENTING WAS TRACED TO ENGINE DRIVEN HYDRAULIC PUMP ACCY DRIVE. PUMP AND DRIVE ASSY WERE REMOVED AND INSP. PLAIN BEARING IN THE ADAPTER HAD SEIZED TO DRIVE SHAFT AND WAS SPINNING IN HOUSING, GALLING AND DEPOSITING SIGNIFICANT AMOUNT OF BRONZE AND ALUMINUM INTO OIL SUMP THROUGH THE ACCY CASE. THIS GALLING PRODUCED ENOUGH HEAT TO MELT REAR SHAFT SEAL WHICH WAS WHY OIL HAD STARTED VENTING OVERBOARD. PARTS WERE ALL REPLACED WITH NEW, ENGINE AND ACCESSORIES FLUSHED.

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