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and that the toggles are all on the outboard side. The pins on the locking plates should not extend beyond the inner surfaces of the adapters or they will foul the gun upon installation. (e) Mount the gun by inserting it, muzzle end first, through the gun compartment, and guide the muzzle through the holes provided in webs 3, 2, and 1. Be sure the front of the gun is properly engaged by the front adapter. (f) Support the rear of the gun with the drift pin stowed in the pocket on the left gun-access door. Insert the drift pin through the rear mount and adapter. (g) Raise the front of the gun enough to en. gage the pins on the locking plates in the holes on the gun. Swing the eye bolt up and lock it with the toggle. (h) Remove the drift pin from the rear adapter and allow the gun to drop down as far as it will go. (i) Release the toggle on the rear adapter to free the saddle, and swing the adapter downward under the gun. (j) Install the solenoid on inboard side of the gun and tighten and safety the attaching nut. (k) Swing the rear adapter up and engage the eye bolt in the saddle. Throw the toggle up to lock the saddle and adapter. (1) Install the rear mounting bolt, which has a flat side to key it to the lateral adjusting sleeve, and insert the lock pin in the bolL Be sure the lock pin is retained by a chain. (m) Tighten the yoke nut through the port in the top surface of the wing with the special gun wrench carried in the stowage pocket on the left wing gun. access door. (n) Attach the link chute to the side of the gun. (o) Insert the blast tube into the leading edge of the wing over the muzzle of the gun. The correct location of each blast tube is given on the name plate attached to the tube. Screw the blast tube onto the retainer on the barrel jacket as far as it will go, then back off the tube approximately half a turn, leaving it with the two locking lugs at the front end of the tube in a vertical position. It is extremely important that the blast tube be backed off approximately half a turn, because if it is tight on the retainer, powder residue will collect in the threads and cause seizure- Slip the leading edge fairing over the blast tube, if necessary moving the shutter so that the opening is in the proper location, and button the fairing to the leading edge with the two Dzus fasteners. A lock in the fairing will engage the blast tube lugs and prevent the tube |
turning off the adapter. Make certain that the cars on the blast tube keep it from turning. If the Dzus fasteners appear to be loose in their securing spring, the springs can be set up by bending them lightly inward. After these operations are completed, it will be noted that the blast tube will have considerable lost motion at its forward end because of the loose-fitting thread in the retainer and the looseness of the retainer on the gun. This is desirable to prevent seizing after extensive firing. (p) Make the necessary alignments and adjustments in accordance with tactical requirements as to direction of fire, and safety all adjustments. 1. Boresight the guns by means of the fixture kit for aligning the guns if one is available, part No. 87-69-980; if not, resort to jacking up the airplane and bore sighting the guns by means of the muzzle adapter f rom the type J -2 boresighting kit with the aid of a target stand and targets. For a step by step procedure, see the general service instruction handbook for all P-40 air. planes. See figures 116 and 116A for the correct setting of the target stand. 2. If the fixture boresighting kit, part No. 87-69-980, happens to be an early model, the index lines for the P-40N series airplanes may not be included on the template; in this case proceed as follows: a. Align the centerline of gun barrel .043 inch above plane for P-40E airplanes. b. Use vertical alignment same as P-40M airplanes. 3. After guns are boresighted, tighten the bolt holding the upper half of the serrated plate on the rear gun mount until the two bushings butt together and full clamping effect is attained. (q) Test the firing solenoid with the guns empty of ammunition by use of the control stick trigger. Listen for the click of the solenoid. (r) If the guns are to be fired, remove the ammunition boxes, load in accordance with the instruction plate on the box top, connect the links between boxes, and feed the ammunition over the feed rollers and into the feed ways of the guns. (s) To load the guns, use a screwdriver inserted from the underside between the gun and feed chute and boost the first round over the belt-holding pawl. Charge each gun with the ground charger which is carried on the gun bay access door in accordance with instructions on the door. The first round will then be held by the bolt. Charge the guns again and the guns will be fully loaded. Charge the guns a third time to eject one cartridge. This is to make certain a shell is in the firing chamber. |
