Cessna 188 Series Service Manual page 392

MODEL 188 & T188 SERIES SERVICE MANUAL
mance are instructions for repair of tubular members,
Service Department.
Figure 17-11 lists the size and
including cluster repairs, split-sleeve reinforce-
wall thickness of each tube used in the structure,
ments, welded-patch repairs, splicing by inner
along with size and wall thickness of repair tube for
sleeve method, splicing by outer sleeve method and
each. Structural alignment, shown in figure 17-1,
splicing by using larger diameter replacement tube.
must be maintained.
17-68. NEGLIGIBLE DAMAGE.
Negligible damage
NOTE
of fuselage tubing should be limited to small smooth
dents, shallow scratches, and minor bowing of tub- Refer to Section 18 for required priming after
ing, not in the middle third of the tube. a welded repair has been accomplished.
17-69. REPAIRABLE DAMAGE.
Dents at a cluster 17-71. ENGINEMOUNT.
may be repaired by a finger type welded patch.
Dented, cracked, or otherwise damaged tubes may
17-72. DESCRIPTION. The mount for the aircraft
be repaired by a welded split-sleeve reinforcement,
engine is constructed of 4130 chrome-molybdenum
after straightening the damaged part and stop drill-
teel tubing. A truss structure, fastened to the fire-
ing cracks with a No. 40 (.98) drill.
Dents or holes wall at four points, supports a cradle arrangement.
in tubes which are not in the middle third of the tube
This cradle arrangement, with its supporting lugs,
and do not result in the patch overlapping a joint may
forms the base for rubber shock mounted engine sup-
be repaired by a welded patch, one gage thicker, if
ports. Enne mounts are illustrated n figure 17-12.
the dents are not deeper than one-tenth of the tube
diameter, do not involve more than one-fourth of the
GENERAL CONSIDERATIONS.
All welding
tube circumference, and are not longer than the tube
diameter; if dents are free from cracks, abrasions
on the engine mount should be of the highest quality
and sharp corners; and If the dented tubing can be
since the tendency of vibration is to accentuate any
substantially reformed without cracking can be ap- minor defect present and cause fatigue cracks. En-
plication of the patch. Holes must cracking be ore ap-
gine mount members are preferably repaired by using
a large diameter replace must
not
be,
telescoped over
tube diameter
must not involve more than one-
the stub of the original member using fishmouth and
fourth of tube circumferencerosette
type welds.
However, reinforced 30-degree
17-70. DAMAGE NECESSTATING REPLACEMENT scarf welds in place of the fishmouth welds are con-
sidered satisfactory for engine mount repair work.
OF PARTS. If extensive damage has occurred, it is
recommended that the complete fuselage tubular
17-74. ENGINE MOUNT SUPPORT CRADLE DAM-
structure assembly be replaced.
Where damage ex- AGE. Minor damage such as a crack adjacent to an
ceeds that specified as negligible or repairable, par-
engine attaching lug may be repaired by rewelding
tial replacement is required. Three methods of
the cradle tube and extending a gusset past the dam-
splicing in partial replacement tubes are acceptable,
aged area. Extensively damaged parts should be re-
all of which are standard procedures outlined in
placed.
Federal Aviation Regulations, Part 43. Splicing by
the inner sleeve method is recommended where a
17-75. DAMAGE INVOLVING ENGINE MOUNTING
smooth tube surface is desired.
Splicing by using
LUGS AND ENGINE MOUNT TO FUSELAGE ATTACH-
a larger diameter replacement tube requires the
ING FITTINGS.
Engine mounting lugs and engine
least amount of cutting and welding, but cannot be
mount to fuselage attaching fittings should not be re-
used where the damaged tube is cut too near adjacent
paired but should be replaced.
clusters or where brackets and the like require the
same size tube.
Splicing by the outer sleeve method 17-76.
BAFFLES ordinarily should be replaced if
requires the greatest amount of welding and should
damaged or cracked.
However, small plate rein-
be used only where the other splicing methods are
forcements riveted to the baffle will often prove
not suitable.
If it should become necessary to re-
satisfactory both to the strength and cooling require-
pair a major attach point fitting, consult the Cessna
ments of the unit.
SHOP NOTES:
17-30