Figure 4-27. Combination Bulkhead and
Universal Fitting Assembly
(7) Installation of Rosan Fluid Fitting will be installed
in accordance with TM 43-0104.
g. Flared Fittings. Flared fittings, like flareless (MS)
come in many different shapes. The main difference
between AN and MS fittings Is the manner in which the
hydraulic tube fits to the fitting. The MS fitting has a
counterbore In which the tubing Is inserted; the AN fitting
has a 37 degree flared (beveled) face to which the tubing is
fitted. This flared area of the fitting is the seating surface
and must be maintained. Any bad flare on this sealing
surface will show up as a hydraulic leak.
(1) Identification. AN flared fittings can be identified
by the part number, as described In table 4-9.
(2) Types. See figure 4-28 for examples of flared
(3) Use of old fittings in oxygen systems. In repairing
oxygen systems, it is usually possible to use the old fittings.
Fittings should be cleaned before they are installed. Refer
to paragraph 4-2g (2) for cleaning procedure for oxygen
(4) Repairing tubing fittings. See figure 4-29 for
repairable and non-repairable defects of tubing fittings.
Tubing fittings may be repaired provided 80 percent of
seat remains after repair. The only marks allowed on seat
surface are annular tool marks of 100 microinches root
mean square maximum. Fittings that cannot be salvaged
by this method should be rejected. Reworked aluminum
alloy fittings should be anodized. Minor scratches are not
cause for replacement If wrench damage to a hexagonal
section of a fitting does not exceed one corner, it should
be reworked with a fine file in such a manner as to leave
no file marks. A maximum of one corner may be
reworked provided 75 percent of reworked flange width is
not damaged. Damaged threads should be inspected and
All screw threads MIL-S-7742, that are within the
pitch diameter tolerances of Class 2, after
rework, are acceptable for further use.
High pressure hose end fitting assemblies, 300
psi and swage-type fittings of any pressure
range, should not be reworked. MIL-F-8789
states that MS28760 and MS28761 fittings
should be used only once.
Coupling nuts sometimes modified for use on
hose end fitting assemblies are not Inter-
changeable with AN8 18 nuts. All AN fittings that
cannot be salvaged by this repair should be
4-4. Repair of Tubing Assembliles. Scratches or nicks
no deeper than 1 percent of the wall thickness in
aluminum alloy tubing may be repaired, if they are not in
the heel of a bend. Replace lines with severe die marks,
seams, or splits in the tube Any crack or deformity in a
flare is also unacceptable and is cause for rejection. A
dent of less than 20 percent of the tube diameter Is not
objectionable, unless it is in the heel of a bend. Dents can
be removed by drawing a bullet of the proper size through
the tube by means of a length of cable.