Chapter XIV: Section XIV: Preventive Maintenance Services

50. GENERAL

Preventive maintenance services, as prescribed by Army Regulations, are a function of using organization echelons of maintenance. These services consist of:

_a._ Before, during, and after operation services performed by the firers and assistants.

_b._ Scheduled services performed by organizational maintenance personnel (service when filling and charging, and service after six firing missions).

51. BEFORE-OPERATION SERVICE OF TANK GROUP.

The following services are to be performed before filling, charging, and loading the flame thrower with pressure, fuel, and ignition cylinder:

_a. Pressure-tank valve._ Open and close pressure-tank valve to test for ease of operation.

_b. Threaded connections._ Check all threaded connections for tightness, using appropriate wrenches.

_c. Tank coupling._ Examine coupling for cleanliness and ease of movement of lock and cams. (Par 70) Clean if necessary. If washer is broken, replace, using screw driver to pry out.

_d. Plugs._ Check filling plug and safety-head plug for completeness of parts (Par 69 _a_) and cleanliness of threads and seats. Clean, if necessary, with cloth. If rod or rod and chain have broken off and fallen in tank, turn tank upside down and remove. Remove deflector tube from head (using hand, not wrench). Inspect to see if diaphragm is intact. If diaphragm is ruptured, replace the safety head with an unbroken head. (Par 69 b, c) Reassemble plug, head, and deflector tube in left fuel tank. (Fig 11) Tube should face to rear and at a 45-degree angle to operator’s left shoulder. (Fig 18) Screw in deflector tube by hand; do not use wrench on deflector tube. Tighten lock nut with wrench.

_e. Pressure-tank clamp._ The clamp should hold the pressure tank tightly in place. If tank is loose, a wooden splint or wedge under the clamp may be used as a temporary expedient.

_f. Carrier-frame bolts._ Check tightness. Use wrench.

_g. Carrier._ (Par 71) Examine all canvas, webbing, and cord for signs of mildew, rot, or wear. Replace defective parts. Move flame thrower to dryer storage if mildew occurs.

_h. Cord (lashing)._ Check for tightness. If necessary, make tighter and use secure, slip-proof knots. When the tank group is filled with fuel and adjusted on the firer, its weight should be carried chiefly by the canvas and webbing, not by the metal frame.

_i. Shoulder and body straps._ Adjust straps to fit firer. (Pars 19 and 71) A loose tank group can cause discomfort or injury when the wearer changes positions while on a mission. Check presence and condition of the two pins and two cotter pins which hold shoulder straps to steel support. Check fasteners.

52. BEFORE-OPERATION SERVICE OF GUN GROUP.

The following services are to be performed before filling, charging, and loading with pressure, fuel, and ignition cylinder:

_a. Hose nipple, tank end._ Examine to be sure nipple is clean and not badly nicked. If badly nicked, the nipple may not make a tight seal at the tank coupling. A leak and loss of pressure may result. See Paragraph 73 _d_ for repair of the nipple.

_b. Fuel hose._ Examine surface of hose for cracks or other signs of deterioration. Special attention should be paid to portions adjacent to the gun and tank coupling, which are subjected to severe flexing. If hose is defective, replace. (Par 73 _b_, _c_) Do not patch.

_c. Hose nipple, gun end._ Check tightness of threaded connection between hose and fuel-valve body, using hand or very light wrench pressure.

_d. Shield._ Remove ignition shield. Check cleanliness of threads on shield and on ignition-head body. If not clean, use cloth. When reassembling (Par 18 _c_), shield should turn freely until it locks in correct position.

_e. Valve lever and needle._

(1) There should be some play in the valve lever. To test, remove ignition shield. Compress grip safety and valve lever slowly, observing the motion of the valve needle. The valve lever should move approximately 1/16 inch before the needle begins to move.

(2) Valve needle should be seated firmly in the barrel nozzle. After the valve lever is pulled back and released, no play should occur in the needle. For adjustment of needle, see Paragraph 75 _d_.

_f. Screws._ Use screw driver to test tightness of all screws.

_g. Spring retainer and plug._ Check tightness of spring retainer and plug (Fig 47) by using hand or very light wrench pressure.

_h. Ignition head._ All exposed surfaces of the shield, nozzle, needle, and other parts of the ignition head, or adjacent to it, should be clean. If not, use cloth.

_i. Atomizer hole._ With the fuel valve held fully open, insert a fine wire in the atomizer hole of the nozzle to clean the hole. Then use cloth-wrapped splint to remove from the inside of the nozzle any foreign matter pushed through the atomizer hole. If such matter is not removed, it may interfere with the closing of the fuel valve needle at the nozzle. Repeat procedure in _e_ (2) above.

_j. Spring case._ Spring case should turn freely on ignition head. If it does not, clean any grease or dirt from, surfaces with cloth and relubricate. (Par 49)

_k. Trigger._ Pull trigger once or twice to find whether it operates easily and whether it returns to position. If not, clean and lubricate trigger. (Par 49) Check condition of trigger spring.

_l. Trigger rod._ Check position of the trigger rod when trigger is pulled back all the way as when firing. The rod should extend approximately 1/16 inch beyond the end of the lug in the ignition head. If it does not, bend the rod slightly, reverse position of bearing, or replace worn parts.

53. SERVICE WHEN FILLING AND CHARGING.

_a. Inspection of fuel tanks._ Just before filling and charging, remove plugs (Par 69 _b_) and examine interior of fuel tanks to see whether they are clean and free from foreign matter. If not clean, flush with gasoline until clean.

_b. Fuel level._ When filling (Pars 37 through 40), see that fuel reaches the same level in both tanks. If leveling does not occur, the tank connector may be clogged with foreign matter. If so, clean, as in _a_, above. After filling, wipe plug seats with a cloth before replacing plugs. Wipe any spilled fuel from weapon.

_c. Pressure-tank valve._ Before charging the tank group with air or nitrogen, open and close the pressure-tank valve several times by hand to be sure it operates freely. If it does not, adjust as described in Paragraph 66 _d_.

_d. Testing for leaks in pressure system._ After charging, and as few hours as possible before a mission, use an 0-3,000-pound gage furnished in service kit to test pressure. (Fig 32) To install gage, unscrew check-valve cap and screw gage in check-valve body. If pressure has fallen below that to which the tank was charged (Par 32), a leak is indicated. Remove gage, replace check-valve cap, and check for leaks at joints between pressure tank and valve and between tank valve and check valve. (A wrench should be used to tighten cap on check-valve body so as to avoid producing an additional leak.) Large leaks can be felt or heard. Small leaks can be detected by coating joints with soap-and-water solution. Bubbles indicate leaks. If a leak is revealed between pressure tank and pressure-tank valve, or between check valve and pressure-tank valve, replace all three as a unit. If tests do not show up the leak the tank may have been improperly charged. It should be recharged and then retested.

54. SERVICE WHEN FIRING.

_a. Failure to ignite._ Pull trigger repeatedly. If ignition cylinder still fails to ignite, dirt may be wedged in ignition head. Unscrew shield one-half turn. Screw it back, rapping shield with the hand while turning. This should dislodge foreign matter. Pull trigger again. Repeat procedure, if necessary.

_b. Safety head “blows” (breaks)._ If safety head breaks, firing mission cannot be carried out. On return, have head replaced. (Par 69) Follow test procedure. (Par 56 _b_)

55. SERVICE AFTER FIRING.

_a. Unloading._ Remove ignition cylinder (Par 30), close pressure-tank valve, and blow out remaining fuel and pressure. (Par 30)

_b. Removal of equipment._ Release the body straps, then the shoulder straps. If prone, lie on side and allow tank group to roll off onto ground. If standing or kneeling, take care that tank group does not drop on feet or legs.

_c. Correcting or reporting._ Correct any failures or difficulties or report them as soon as possible to service or maintenance personnel.

_d. Gun._ Remove shield (Par 18) and clean interior of shield with cloth. Clean holes in shield with wire or wooden splint. Clean external surfaces of barrel, nozzle, needle, and other parts. Check cleanliness and adjustment of needle. (Par 75 _d_) Check trigger for operation. Lubricate. (Par 49)

_e. Fuel tanks and passages._ Remove plugs (Par 69 _b_). Drain any remaining fuel. Use gasoline to remove residues of thickened fuels before they have a chance to harden and obstruct passages. If necessary, fill tanks with gasoline and allow to stand for several hours, shaking occasionally. Drain and repeat if necessary.

_f. Safety head._ Check head to see if it is ruptured; if it is, replace. (Par 69) Follow test procedure. (Par 56 _b_)

_g. Pressure-tank valve._ If weapon is to be stored, open pressure-tank valve and leave it open until next charging.

_h. Carrier._ Scrub, if necessary, with soap and water, or gasoline.

_i. Exterior metal surfaces._ Scrub exterior metal surfaces clean of fuel to prevent fire hazard. Allow to dry before using again.

_j. General inspection._ Carefully examine all other parts, adjust as necessary, and replace any which are damaged.

56. SERVICE AFTER SIX FIRING MISSIONS.

After the flame thrower has been used on six firing missions or the equivalent in training work, experienced personnel should follow these directions:

_a. Before-operation and after-operation service._ Follow the same procedures as in Paragraphs 52, 53, and 55.

_b. Test firing (or simulated firing)._

(1) If tactical conditions permit test firing at a suitable test range (Par 15), fill the fuel tanks with fuel. (Pars 37 through 40)

(2) If test firing with fuel is impracticable, fill fuel tanks with clean water. (Be sure to dry all parts after test.)

(3) _Remove filling-plug assembly._ (Par 69) Fish out the retainer rod and chain by means of a bent wire.

(4) Do not unscrew the safety-head plug.

(5) Insert the testing plug with 0-to 500-pound pressure gage (plug and gage are from service kit) in the filling-plug opening. Tighten testing plug in seat with wrench.

(6) Fully charge pressure tank. (Par 32)

(7) If test firing with fuel, load ignition cylinder. (Par 18)

(8) Open pressure-tank valve and simultaneously observe pressure in fuel tanks by reading gage. The gage indicates the pressure in both tanks. It should be between 350 and 390 pounds per square inch.

(9) Read the gage at the expiration of not less than 5 minutes. The tanks should have a pressure reading of not more than 390 pounds. If the pressure continues to increase beyond 390 pounds and the safety head blows, replace the safety head and the pressure regulator.

(10) Fire by operating controls (or simulate firing if tanks are filled with water). The burst should last 3 seconds, during which time the pressure should not drop below 260 pounds.

(11) If the pressure does not conform to the requirements stated in (8), (9), and (10), adjust the pressure regulator upward or downward. (Par 67 _d_)

(12) While the above test firing is proceeding, check for leaks at all joints and connections on the tank group. The pressure system should be checked by painting the joints with soap-and-water solution and by looking for bubbles which indicate leaks. For replacement of parts where pressure leaks, see Paragraph 66. Fuel leaks may be seen without soap and water. For repair of fuel leaks, see Paragraph 75 _e_. The nozzle should be observed by removing the ignition shield. Nozzle leaks are corrected by cleaning, adjusting needle (Par 75 _d_), or by regrinding. (Par 75 _e_) If this is not successful, replace both needle and barrel as a unit.

_c. Fuel valve._ Discharge all pressure from the gun by operating the fuel valve. Carefully remove the valve grip and grip support. (Par 74) Look for signs of leakage at the valve diaphragm. If a leak is present, replace valve-diaphragm assembly. (Pars 75 _b_ and 75 _c_)

_d. Valve grip._ Disassemble the valve grip (Par 74) and lubricate. (Par 49)

_e. Carrier._ Tighten the carrier cord.

_f. Gun interior._ If thickened fuel has been fired, disassemble the gun. All parts should be cleaned of accumulations of dried fuel. Lubricate (Par 49) and reassemble. If liquid fuel has been fired, flush gun with clean gasoline. Disassemble only enough to lubricate. Reassemble.