The flotation tube is separated into two compartments by internal vertical bulkheads. Bulkheads are constructed of laminated cloth and are of a six-gore hemispherical design. The bulkheads are installed amidships, equidistant from the bow and stern so that the volume of the two compartments is equal. A 4-inch-diameter patch of laminated cloth is securely cemented to each side of the bulkhead, at the manifold, to protect the bulkhead against abrasion by the manifold diffusers when the raft is packed in the carrying case.
An inflatable seat is installed in certain multiplace life rafts; for example, the LRU-12/A, LRU-13/A, and LRU-14 series. These seats are circular and are made of laminated cloth. The ends of the seat are tailored to fit the curvature of the flotation tube. The inflatable seat is an independent air chamber and is manually inflated through the topping-off valve by using the hand pump provided. It is attached to the bottom of the raft with Y-shaped hinge tapes made of laminated cloth. This method of attachment allows for expansion and prevents undue stresses between the bottom of the raft and the seat.
Each LRU-12/A, LRU-13/A, and LRU-14 series life raft contains a supply pocket that measures approximately 8 x 8 x 2 inches. The pocket is attached to the starboard side of the flotation tube surface inside the raft by stitching the pocket to a patch and cementing the patch to
the tube. Using black washproof ink, ensure that each pocket is clearly marked SUPPLY POCKET in 1/2-inch letters on the LRU-12/A and LRU-13/A rafts. The lettering should be l-inch high on the LRU-14 series supply pocket.
In addition to the starboard supply pocket, the LRU-14 series raft has a port supply pocket. This pocket is attached to the raft in the same manner as previously discussed. The lettering height on the port pocket is 1 inch for the first line and 1/4 inch for all other lines.
COMBINATION SUPPLY POCKET AND BAILER
Each life raft, except the LRU-15/A, contains one detachable combination supply pocket and bailer. The pocket is closed by means of a slide fastener across the top, which is sealed with tape after the equipment is packed. A loop of spring wire is contained in the seam around the slide fastener so that the pocket may be fashioned into a bailing container. One end of a 5-foot length of type III nylon suspension line is secured to the slide fastener wire stirrup pull; the other end is attached to the nearest lifeline patch loop.
The words SUPPLIES AND BAILER are stenciled in 1/2-inch letters on the pocket. Below this, stenciled in 1/4-inch letters, are the pocket contents.
The Supply and Bailer pocket on the STBD side of LRU-12/A, -13/A, and -14 series has been deleted from newly procured rafts. New rafts are not reworked to provide pocket and on older rafts they need not be removed.
A lifeline of natural color nylon rope, 1/4-inch diameter, encircles the outboard perimeter of the raft. The lifeline is attached to each lifeline patch loop with an overhand knot tied on the inner side of each patch loop so as to prevent the line from running free through the loops. Four inches of slack is allowed in the line between the lifeline patch loops. Each completed lifeline patch can withstand a 250pound pull exerted in a direction perpendicular to the base of the patch.
The lifeline provides a means for securing the accessory containers to the life raft by using a 10-foot length of type 111 nylon cord.
The LRU-15/A life raft also has an inner lifeline that provides for the safety and survival of aircrewmen.
Righting handles are provided on all life rafts except the LRU-15/A. These handles provide a means of righting a capsized raft.
Topping-off valves are installed on each flotation tube, inflatable seat, each section of inflatable floors, and each side of the floor supports. The required number of topping-off valves and their location on the rafts may vary depending on the type of raft concerned.
Topping-off valves are used for manual inflation purposes in conjunction with the hand pump. The valve also serves as a means for relieving high internal tube pressure that may possibly build up during hot, sunny days.
Two topping-off valves are installed on the same side of the raft's main flotation tube-one on each side of the internal bulkhead-above the inside horizontal centerline of the tube, 4 inches from the point of attachment of the vertical internal bulkhead.
Stenciled instructions relative to topping-off and deflation of the raft are applied on the raft flotation tube adjacent to the topping-off valves. Appearing in 1/4-inch, washproof black ink letters, the instructions are stenciled on a white rubber patch as follows:
TO INFLATE COMPARTMENTS MANUALLY: Attach hand pump to valve cap, unscrew cap 1 1/2 turns to the right and then pump to inflate. When desired pressure is attained, retighten valve cap and remove pump.
TO DECREASE PRESSURE: Open valve 1 1/2 turns to the right and bleed.
The valve of the CO2 cylinder is threaded into the coupling nut of the manifold. Since multiplace life rafts are constructed with internal bulkheads, the purpose of the manifold is to provide a common means of directing and diffusing the flow of carbon dioxide entering the raft's inflatable tube chamber. The manifold outlets must bridge the internal bulkhead over which they are mounted. Figure 6-1 illustrates the operation of the raft's CO2 inflation system manifold.
All of the exposed metal surfaces of the inflation system that might chafe the raft fabric while packed must be covered with several layers of rubber-coated cloth, and secured with clothbased, pressure-sensitive tape.
Because of space limitation, this chapter cannot possibly contain all of the available information concerning life rafts. The Inflatable Survival Equipment Manual, NAVAIR 13-1-6.1, is referenced for more detailed information.
Figure 6-1.-Multiplace raft CO
2 inflation system manifold operation. LRU-12/A LIFE RAFT ASSEMBLY
The LRU-12/A life raft assembly consists of an inflation assembly (carbon dioxide cylinder and inflation valve) and a four-man raft. Two types of carbon dioxide cylinders and four types of inflation valves are approved for service use. The life raft is made up of a twocompartment main tube; an inflatable seat attached to the main tube; a noninf'latable floor attached to the bottom of the main tube and inflatable seat; and a sea anchor, which is used to retard drifting. A lifeline, a righting line, a supply pocket, and a combination supply pocket and bailer are attached to the main tube.
Boarding and righting handles are attached to the main tube and the floor. Emergency survival equipment and raft accessories, stowed in accessory containers, are provided for the safety and survival of the aircrewmen. The lifeline also provides a means for securing the accessory containers to the life raft. Topping-off valves are located on the main tube and inflatable seat. An LRU-12/A life raft is shown in figure 6-2.
NOTE: To makeup the packaged life raft assembly complete with accessories and survival items, all required components not supplied with the raft assembly must be individually requisitioned.
The LRU-12/A life raft assembly (droppable) is inflated by pulling the inflation assembly actuating handle, located under the carrying case end flap. The LRU-12/A life raft assembly (raft compartment installation) is automatically inflated and ejected after the raft compartment door has been released. After boarding, the inflatable seat should be inflated through the topping-off valves with the hand pump provided in the accessory container.
The LRU-12/A life raft assembly can either be dropped to survivors or used by aircrewmen in the event of an aircraft ditching emergency. The raft is stowed in a readily accessible area inside the aircraft fuselage on all applicable aircraft except the S-2 series.
Prior to packing any life raft, the assembly must be updated by comparing the configuration of the assembly with the modifications listed in the applicable chapter in NAVAIR 13-1-6.1.
Survival items are intended to provide a means for sustaining life, aiding in escape and evasion, and for a suitable detection capability. Survival items may be packed in life rafts, droppable kits, kits intended to be carried or worn by the aircrewmen, or they may be individually carried.
The equipment and survival items carried in the LRU-12/A life raft assembly differ from that carried in other rafts basically in the quantity carried, with a few minor exceptions. Table 6-5 lists the survival item requirements and the applicable item storage container and pocket for LRU-12/A, LRU-13/A, LRU-14 series, and LRU-15/A life rafts.