TM 5-1940-321-13&P
( 8 ) Wait five minutes and repeat step ( 7 ) above.
( 9 ) Wait five minutes and apply the patch to the craft. Smooth it down evenly,
rubbing from the center of the patch outward in all directions.
( 10 ) Using the handle end of a knife or other smooth object, rub the patch down
with moderate pressure. Rub down the entire patch with a crisscross motion for
one full minute.
( 11 ) Return all material to the repair kit and stow it in the bow pouch.
( 12 ) If possible, wait at least 24 hours for the glue to cure before inflating the air
chamber or using the craft. If absolutely necessary, the waiting period can be
reduced to three hours.
7-8. VALVE LEAKS. Leaks may occur at several points on any valve. The valve internal mechanism
may stick causing air to leak. Gaskets and O-rings may be worn or not properly seated, causing air to
leak. The gaskets between the valve and the air chamber fabric may leak. The exact point at which a
valve is leaking must be known in order to perform corrective maintenance.
a. Locating Valve Leaks. With all four intercommunicating valve flywheels placed in the
NAVIGATION position (indicating arrow on flywheel at 6 o clock position), the buoyancy tube air
chambers will be isolated from each other. The isolator clamps isolate the lower buoyancy tubes from the
main buoyancy tubes.
The inflatable keel is a separate air chamber isolated from the other seven air chambers. With
the eight air chambers isolated from each other, the chamber that is leaking will be obvious since it will be
deflated or underinflated. If one air leak is located do not assume it is the only leak. Paragraph 6-3 in
chapter 6 provides a procedure to locate leaks exactly, using a soap and water bubble test. For valve
leaks, the exact point on the valve that leaks must be identified. Figures 7-1 through 7-5 show different
locations for valve leaks and their possible causes.
b. Correcting Valve Leaks. While underway in the craft or during some other situations, it
may not be possible to perform the normal troubleshooting procedures to identify the cause of an air leak.
Air may be replenished using the foot pumps if the leak is not large. Other corrective actions may be
taken while underway to correct leaking valves. These immediate corrective actions, to be performed by
unit personnel, are discussed below under each valve type. More extensive corrective maintenance for
each valve is also discussed.
7-4
