TM 5-1940-321-13&P
Figure F-14. Tracing the Patch onto the Craft with a Silver Pen.
( 5 ) Wait 18 hours before testing the inner patch. Inflate the craft to 180 mbar only,
and then perform the soap and water air leak test ( chapter 6, paragraph 6-3)
on the patched area.
( 6 ) An outer patch is always applied over and inner patch. If the soap and water
test indicates the inner patch is airtight, trace an external patch that is one inch
larger on all sides than the inner patch already applied. Apply the outer patch.
e. Patching Tears at Seams. Tears at seams are repaired with an inner and outer patch as
described above. Inside seams are covered with a sealing mastic during construction of the craft. The
sealing mastic must be removed by grinding, and an inner patch must be applied. The inner mastic is
removed by manually grinding it away with a hand-held pumice stone. The inner patch is applied as
described in paragraph F-6d above.
f. Large Tears in Buoyancy Tube. Large tears (more than 6 inches long) in buoyancy tubes
are repaired using the same procedure used for small tears. An inner and outer patch is applied as
described in paragraph F-6d above. Some additional consideration follows:
( 1 ) The inner patch must be one large patch. Two inner patches applied next to
each other will not be air tight.
( 2 ) Trace the position of the inner patch on the outside of the tube before
attempting to fit it. Also trace the position of the tear on the inner patch. The
tracing will assist in aligning of the patch in its correct position.
F-21
