Service and Repair Manual

AN 01-25CN-2

PARAGRAPH 6

   (e) PRIMER-The engine primer system consists of a supply line from the electric fuel pump to the primer, and a line from the primer to the engine intake manifolds. The priming system on the engine is independent of the carburetor and pumping the carburetor throttle will not discharge fuel into the engine.

   (f) SCUPPER DRAINS-The wing tank scuppers in the left wing fillet are provided with drain lines passing downward through the lower wing skin just to the left of the tank door.

  (3) REMOVAL OF TANKS.

   (a) TO REMOVE THE BELLY TANK.

   1. Drain the tank through the drain cock on the bottom of the tank and be sure that all safety pre. cautions are taken to prevent fire or explosion. Have at least two hand fire extinguishers within reach.

   2. Unbutton the oil drain access door on the right side of the exit duct and loosen the two clamp fittings on the synthetic rubber hose connection on the fuel supply line to the selector valve. Take the synthetic rubber cap (Drawing No. 87-44-56&1) from the toot kit and install it on the end of the fuel selector valve line.

   3. Cut the lock wire on the sway brace turnbuckle barrels and back off the sway braces .

   4. Unbutton the fuel tank drain-access door and, with a man supporting the tank at the forward and aft ends, insert a hand in the access door opening and pull back on the release lever at the front of the shackle. This procedure will release the carrying hooks and allow the tank to drop free of the shackle. Use extreme caution when removing the belly tank not to damage the short feed line connection on top of the tank. Remove the tank from under the airplane, and if the tank is not completely empty, be sure to keep the tank upright until it is thoroughly drained. Spilling fuel creates a dangerous fire hazard and extreme care should be exercised to guard against it. If fuel is accidentally spilled, clean it up immediately.

   (b) TO REMOVE EITHER WING FUEL CELL (see Fig. 90).

  1. Remove the inboard, fixed landing gear fairing.

  2. Disconnect and remove the belly tank sway braces.

  3. Remove the keel fairing.

  4. Remove the wing fillets.

  5. Drain the fuel cells.

  6. Disconnect the vent lines at the top of the fuel cells above the upper wing skin.

  7. Remove the control cables and the bomb shackle.

  8. Remove fuel lines, fuel gages, and filler caps. All connections to the self-sealing fuel cells must be broken, otherwise they will be torn at the fittings.

  9. Remove the retaining nut on the gage neck.

  10. Remove the filler cap on the filler neck and then unscrew the filler neck.

  11. Remove the fuel tank doors in the bottom of the wing as a single unit as follows:

    a. Withdraw the bolts at each end of the skid, which attach the skid to the match angles.

    b. Remove all screws and bolts which attach the doors to the wing, including the screws and bolts through web 3.

  12. Remove bonding.

  13. Remove tank straps.

  14. Remove the fuel cell from the wing, taking care that no damage occurs to the filler-neck, gage, and vent line fittings, which extend through the wing skin.

(4) REPAIR OF SELF-SEALING FUEL CELLS. -The following procedure is recommended for the repair of the fuel cells. T.O. 03-1026 entitled, "Repair Instructions--Self-Sealing Fuel Cells," dated 12-1-42, gives detailed instructions on this subject.c cowl shutters. There is also a strainer in the carburetor.

   (c) FUEL SELECTOR VALVE-The fuel selector valve is mounted on a support on the wing match angle near the leading edge and is controlled by a rod through the leading edge to a gear box on the forward left side of the firewall. Another control rod runs from the gear box through the firewall into the cockpit to the indicator plate handle. When the engine is not running, a decided "click" can be heard when the indicating plate is engaged. When the engine is running, this engagement can be felt through the control handle. It is mandatory that the fuel selector valve settings be determined by this "click" or "feel" method and not solely by the position of the control handle pointer in the cockpit. If this precaution is not taken, fuel may flow between tanks, creating a very dangerous condition. Inability to hear the "click" or "feel" the engagement is usually caused by excessive drag in the fuel valve or by interference of the ro& with other parts. Whenever this condition occurs, the control linkage, will be disconnected at the fuel selector valve yoke and both the control linkage and fuel selector valve assembly will be checked for freedom of movement. Drag in the fuel selector valve assembly can be determined by turning the selector valve stem yoke with the fingers.