Service difficulty report · Isolation Mount · Cessna 140

Difficulty date
August 1, 2024
Submitted
August 1, 2024
Operation
General aviation
Aircraft
N72885
Make and model
Cessna 140
Aircraft serial
10079
Engine
Cont C8512F
Part
Isolation Mount
Part number
SA22387
Condition
Cracked
Location
Engine Mount
Component
Engine Mount · Cont
Component part number
C8512F
Stage of operation
IN
How discovered
V
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

DURING THE REPLACEMENT OF THE ENGINE MOUNTS, WE FOUND THAT THE TORQUE CALLED OUT IN THE MAINTENANCE MANUAL (CESSNA 100- SERIES SERVICE MANUAL 1962 AND PRIOR PARA 12-10(B) AND PAGE 1-8 FOR 3/8-24 AN310 SELF LOCKING NUT NOTE 2 (160-190 IN. LBS)) APPEARS TO BE EXCESSIVE AND CAUSES THE RUBBER TO BE SQUEEZED TO HARD AND NEW ENGINE MOUNT RUBBER APPEARS TO SHOW SIGNS OF CRACKING IMMEDIATELY. LOWER TORQUE VALUES DO NOT CAUSE THIS. AFTER FURTHER RESEARCH, A DRAWING WAS FOUND IN THE ENGINE OVERHAUL MANUAL (PUBLICATION X30010 OVERHAUL MANUAL) CALLS FOR A SIGNIFICANTLY LOWER TORQUE (PAGE 34-36, (REF. 60-80 IN. LBS.)) WE ARE LOOKING FOR CLARIFICATION ON WHAT TORQUE TO USE. THE CONTINENTAL OVERHAUL MANUAL OR THE CESSNA SERVICE MANUAL.

More about the Cessna 140