Cessna 172 Maintenance Manual page 164

1. General
A. The engine mount is fabricated from 4130 chrome-molybdenum steel tubing. The mount attaches to
the firewall at four points and to the engine using rubber isolation mounts at four points.
NOTE: Repair by gas welding is acceptable.
2. Engine Mount Repairs
A. The following procedures are to be used when making repairs to the engine mount. Refer to Figure
801.
(1) All welding on the engine mounts should be of the highest quality, since the tendency of vibration
will accentuate any minor defect present and cause fatigue cracks. Engine mount members
are preferably repaired by using larger diameter replacement tube welds. However, reinforced
30-degree scarf welds in place of the fishmouth welds are considered satisfactory for engine
mount repair work.
(2) Minor damage, such as a crack adjacent to an engine attaching lug, may be repaired by
rewelding the tube and extending a gusset past the damaged area. Extensively damaged parts
must be replaced.
(3) Engine mounting lugs and engine mount-to-fuselage attach fittings should be replaced, not
repaired.
(4) For information on damage beyond the scope of these repairs, consult Cessna Propeller
Aircraft Product Support, P.O. Box 7706, Wichita, KS 67277 USA, Telephone (316) 517-5800
or Facsimile (316) 942-9006.
CESSNA AIRCRAFT COMPANY
SINGLE ENGINE
STRUCTURAL REPAIR MANUAL
DYNAFOCAL-TYPE ENGINE MOUNT REPAIRS
© Cessna Aircraft Company
71-20-00
Page 801
Jun 1/2005