The shell sections are bolted together with the leather covering of the fuel bag fastened between its flanges. (See figure 7.) The fuselage container or shell is reinforced by means of straps.

     (2) Repair of Fuel Bag on the Side Which the Bullet Enters. - A small clean hole, which would usually result from a bullet entering a tank, may be repaired as follows:

     (a) Clean the neoprene balloon cloth lining around the bullet hole with ethyl acetate solution to remove the zinc chromate slushing compound. Allow to dry and buff lightly where the patch will fit. Use two coats of Bostlck M-40 cement on both the neoprene fabric patch and the liner of the bag. The patch`should extend at least I inch beyond the damaged area in all directions.

     (b) Brush on TL-284 zinc chromite slushing compound so that the repaired area is completely covered.

     (c) Rough up the steer-hide leather on the outside of the bag with card cloth around the damaged area. Cement the leather surface with two coats of M-40 cement and allow to dry 15 minutes.

     (d) Prepare a patch by cementing the flesh side of the steer-hide leather with two coats of M-40 cement. Allow to dry, and apply the leather patch to the prepared area and hand roll thoroughly. (See figure 9.)

     (3) Repair at Fuel Bag on me side from which the Bullet Emerges. - Any extensive damage or large tear in the bag may be repaired as follows:

     (a) Repair the inner neoprene lining is the same manner as detailed above.

     (b) On the outside leather surface draw a circle around the damaged area so that no part of the circle will fall closer than 2 inches to any part of the damaged area. Remove this section of the steer-hide leather using benzol and a knife.

     (c) Remove the outer layer of Latex and sponge from a concentric circle having a 1/2-inch smaller radius than the previously removed steer hide.

     NOTE: The Latex and sponge are removed simultaneously over an equal area. (See figure 9.)

     (d) Remove the inner layer of Latex from a concentric circle having a 1-inch smaller radius than the previously removed steer hide or a 1/2-inch smaller radius than the previously removed Latex and sponge.

     (e) Remove any loose particles of the split steer hide.

           (f) Cut patches of steer hide, Latex sheet, sponge and split steer hide. These patches should be large enough to make a lap joint on each step of this repair except in the case of the sponge patch where a butt joint should be used instead of a lap joint. Each lap is 1/2 inch except the outer layer of steer hide which should lap 1 inch. (See figure 9.) Use two coats of Bostlck M-40 cement on each surface.

     (g) The bag layers should be repaired as soon as possible after damage, because the Latex gum swells at the rate of 2000 percent is 48 hours when saturated with 100 octane fuel. The area affected will spread rapidly and unless repaired immediately, the fuel bag may have to be scrapped.

     (h) Emergency temporary repairs made by merely patching the inside of the inner lining would prove effective where the tear does not exceed 4 inches, provided the aluminum shell is hammered back into shape to support the self-sealing element where it is damaged.

     (i) Bostick M-40 cement should be used to repair self-sealing fuel bags. This is a self-vulcanizing cement and tends to deteriorate if stored for long periods. It is, therefore, advisable to order supplies in small quantities as it is necessary to mix the cement with a curing fluid before use and once mixed, it starts to vulcanize rapidly. Therefore, mix only sufficient cement to do the job on hand. Never use previously mixed M-40 Bostlck cement. Benzol or Toluol may be used as a cement thirmer. Toluol is used in the M-40 Bostick cement.

     NOTE: Both benzol and Toluol have severe toxic effects and, consequently, must be used only in a location that will afford ample ventilation to protect the repair personnel from any ill effects.

     (4) Repair Around Fittings. -Leaking or damaged pipe fittings may be easily repaired. Loosen the defective fitting by pouring benzol or Toluol down the outside of the pipe so that it seeps between the flange of the fitting and the balloon cloth. The fitting when loosened, may be pushed into the bag and removed through the inspection hole. The jointing surfaces must be cleared of the zinc chromite slushing compound before applying the Bostlck M-40 cement. A balloon patch should be cemented to the flange before the fitting is cemented inside the bag. Care should be exercised to work from the center out when attaching the fittings or patches so that no air will be trapped between the surfaces.

     (5) Repair Materials.

     (a) Neoprene synthetic rubber fabric liner, Specification No. 16112-A.

     (b) Benzol or Toluol cement thinner.