TM 5-1940-321-13&P
7-21. REPAIRING DAMAGED BUOYANCY TUBES. This corrective maintenance procedure is
performed by direct support personnel. Damaged buoyancy tubes are repaired by applying fabric patches
to the damaged area. The application of fabric patches requires a thorough knowledge of the procedures
in Appendix F. Small pinhole punctures can be repaired with a single outer patch. Tears in the buoyancy
tube fabric longer than 4 inches are repaired by applying an inner and outer patch as described in
Appendix F, paragraph F-6d. All buoyancy tube patches are cut from hypalon neoprene fabric. All
patching should be performed as described in Appendix F. Leaks in buoyancy tube seams are repaired
as described in paragraph 7-22a. Air loss due to pinholes in buoyancy tube fabric is corrected as
described in paragraph 7-22b. All patches applied to buoyancy tubes must be tested for air leaks using
the soap and water test described in chapter 6, paragraph 6-3.
7-22. RESTORING AIR TIGHTNESS TO AN OLDER CRAFT. This corrective maintenance procedure is
performed by direct support personnel. After a craft has been in service for an extended period of time, it
may not pass the 24-hour pressure retention test (chapter 5, paragraph 5-20) due to numerous small air
leaks occurring at many places on the craft. This is indicated by performing the air leak test (chapter 6,
paragraph 6-3). The widespread loss of air from many places on the craft normally has two causes; seam
leaks and a multitude of very small (pin) holes. The air leak test will indicate which. Both seam leaks and
small holes can be corrected. Seam leaks are corrected by seam.bandaging; the application of an outer
fabric bandage to the entire sem. Widespread pinholes are corrected by filling the pores in the buoyancy
tubes with a latex rubber compound. Small areas of fabric pinholes can be corrected by applying an outer
patch to the affected area as described in Appendix F. Small areas of fabric air loss are often caused by
the fabric coating becoming worn allowing air to escape.
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