TM-9-2815-200-35
ENGINE, WITH CONTAINER:TURBOSUPERCHARGED, DIESEL ,FUEL INJECTION ,90-DEGREE “V” TYPE, AIR - COOLED ,12 - CYLINDER , ASSEMBLY ;MODELS AVDS-1790-2M (2815-856-4996), AVDS-1790-2A AND AVDS-1790-2AM (2815-856-9005)
TECHNICAL MANUAL; DIRECT SUPPORT, GENERAL SUPPORT AND DEPOT MAINTENANCE MANUAL INCLUDING REPAIR PARTS AND SPECIAL TOOLS LISTS
TM-9-2815-200-35 - Page 299 of 779
necessary and check for broken welds, loos e
rivets or weld nuts. If parts are cracked or torn,
they must be repaired or replaced. Check shroud
seals for hardness, tears, or other damage. Mark
damaged seals for replacement if the part i s
otherwise serviceable .
6-4. Repair
a .
General.
Most engine parts and com -
ponents may be repaired as outlined below. After
repair, clean all parts thoroughly to preven t
metal chips from repair operations, or abrasive s
used in repair operations, from entering working
parts of the engine .
b. General Repair of Castings .
(1) Replace all castings when cracks have
penetrated high stress areas such as fillets o r
webbing .
(2) Replace all castings which do no t
conform to tolerances specified in the ap -
propriate repair and rebuild standards table .
(3) Replace all castings on which machined
surfaces are burred or nicked to the point o f
impairing subsequent assembly or operation .
Repair minor damage to machined surfaces with
a fine mill file or crocus cloth dipped in dry -
cleaning solvent or mineral spirits paint thinner .
(4) Replace all castings having flange s
which are severely warped and cannot b e
repaired to provide a proper seating surface with
its mating part. Repair minor warpage o f
mounting flanges and mounting pads by working
surface across a sheet of crocus cloth held tightly
on a surface plate or similar flat surface .
(5) Repair damaged pipe threads in tapped
holes with a used tap .
Note.
Pipe plug threads in castings must be
in good condition to prevent oil leakage .
c.
Welding of Aluminum Alloy Castings .
Note.
The following procedures (1) throug h
(7) are based on the applicable paragraphs i n
Specification MIL-W-8604 and MIL-W-45205 ,
and outline the requirements, equipment, an d
welding process used for the repair of aluminu m
alloy castings .
Specific information relating t o
the welding of individual castings will be covered
in the appropriate section of this chapter .
(1)
Operator.
Welding shall be performe d
by welding operators who have successfully me t
the requirements of Specification MIL-T-5021 ,
for Material Group IV (Aluminum Alloys) .
Operational :
TM 9-237 (Nov. 1967). The bas e
material covered in this procedure is Type 355 -
T71 Federal Specification QQ-A-601 .
(2)
Equipment.
An alternating current ar c
weldin g
machine shall be used for heliar c
welding. Class 4043, conforming to Specification
QQ-R-566a or MIL-E-16053 welding rod, i s
compatible with the base material and shall be
used for all welding repairs in this materia l
group. All equipment shall be consistent wit h
good standard welding practices, and be ac -
ceptable to the Government Inspector .
(3)
Processes .
(a)
MIG (Metal Inert Gas) process.
Th e
MIG process is recommended when weldin g
aluminum plate greater tha n
1/8
inch
thickness .
(b)
TIG (Tungsten Inert Gas) process .
When welding aluminum plate 1/8 inch thic k
and under, the TIG process is recommended .
(4)
Casting preparation .
(a)
Cleaning.
All foreign material mus t
be removed from the area to be welded prior to
repair operations. The area shall be cleane d
using a stainless steel wire brush, drill, burring
tool, or approved chemical process, whichever i s
applicable .
(b)
Cracks.
Determine flow of cracks by
using dye check method. Drill stop holes at crack
ends with a 1 / 4-inch drill and mill out cracks to
provide a “V” aperture .
(c)
Fractures.
Check
area
around
the
fracture for cracks using dye check. Drill stop
holes at the ends of detected cracks with a 1/4 -
inch drill and mill out crack to provide a “V”
aperture .
(d)
Missing metal.
If the size of th e
damaged area permits, mill out and chamfer tha t
area to 30 degrees to provide a 60 degree in -
cluded angle. The insert piece required for thi s
area must be identical in composition and may
be cut from scrapped castings or suitable shee t
stock. Fit insert piece into milled area, so tha t
1/6-
to
1/8-inch
is
maintained
between
insert
and casting wall .
(5)
Preparation for welding .
Precisely
measure castings at appropriate locations t o
detect dimensional changes caused by weldin g
repair .
Record dimensions for checking afte r
repair has been made to be sure that critica l
dimensions have been held .
(6)
Preheat prior to welding .
Prehea t
6-5
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