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B-17 Crew Requirements and Standard Operating Procedures
Crew Composition Crewmen Duties Clothing Oxygen Navigators Bombardiers Gunners Observers
Intelligence Engines Take-off and Assembly Formation 41st CBW Assembly Landing Sorties

APO 557, U.S. ARMY
15 October 1944


    1. All gunners, Navigators and Bombardiers will be responsible for cleaning their guns.

      1. The guns will be cleaned not later than the evening of the day on which they are fired. Never, under any circumstances, permit a gun to be set without cleaning it after it has been fired.

      2. When GUNS are being fired, the pores of the metal tends to open and expand. With this expansion, a certain amount of moisture is absorbed. When the guns have been cleaned and stored away, the metal pores of the guns contract and force a slight amount of moisture to the surface and the rust starts to form. One cleaning is not sufficient to prevent this rust, and the guns must be cleaned every day for at least seven days and left with a thin coating of oil after each cleaning.

      3. All working parts of the gun will be disassembled and cleaned thoroughly with gasoline. Dry the parts immediately after removing the gasoline. Then the parts will be wiped with an oiled rag, oiled with AXS 777.

      4. The BORE will be cleaned with bore cleaner; saturate a clean patch with bore cleaner and run through bore. Repeat with clean patched saturated with bore cleaner two (2) or three (3) times until a clean patch picks up NO foreign matter. Then use a clean dry patch to remove all the cleaner before applying lubricating oil Spec. No. AXS 777.

      5. Proper oiling is second in importance only to intelligent cleaning. All working parts of the gun must be oiled, but sparingly.

        1. In oiling aircraft guns, be careful not to use too much oil. In low temperatures the oil will congeal and cause MALFUNCTIONS. It is best to OIL by wiping with an oiled rag.

        2. Lubricating oil, Specification No. AXS 777 will be used on all machine guns. This oil is not considered a suitable preservative. It must be renewed every 48 hours.

      6. The oil buffer will be filled while cleaning the gun after it has been fired. It will be checked again before assembling to se that it is full and has not leaked.

        1. Recoil Oil Spec. No. 2-36D will be used in the oil buffer.
        2. The OIL BUFFER will be set at TWO (2) notches from full open.

      7. On damp and rainy days, the receivers, barrel jackets, and barrel jacket bearing will be wiped free from moisture. This must be done to prevent FREEZING of the gun at altitude.

      8. After the guns have been assembled, the gunners will PREFLIGHT their respective positions.

        1. Turret Operators will check their respective turrets for complete operation before take-off.

        2. Ball Turret Gunners will make sure his ammunition cover is fastened securely.

        3. For correct procedure to adjust G-11 solenoid, the turret operators will check with their Turret Sections.

    2. All Ordnance and Armament malfunctions will be left intact for investigation by the Armament Officer if it is unrepairable in the air.

    3. All Guns will be test fired with at least fifty (50) rounds every third combat mission or whenever BRIEFED to do so. Airplane commanders will insure that the guns are fired only in such places where they will not endanger friendly troops and installations. This is very important because negligence in handling the Caliber .50 machine gun has resulted in needless deaths as well as damage to aircraft.

    4. Bendix Chin Turret guns will be STOWED in the extreme right position at a minus three (3) degrees elevation to prevent moisture draining down the barrels into the receiver group.

    5. Modification of Combat Loading:

      1. The radio hatch gun with its accessories and ammunition will be removed.

      2. Only one waist gunner will be carried and will ride in the radio compartment from time of take-off until altitude is reached, or within thirty (30) minutes of the enemy coast, whichever is first.

      3. Ammunition load will be limited to 800 rounds in the tail gun position and 350 rounds at each waist gun position, with spare ammunition not to exceed two (2) cases, divided between the nose and radio compartments.

    6. Modification for Prevention of Oxygen Fires in the Upper Turret:

      1. Installation of Emergency Oxygen Shut-Off Valve on the rear frame of the pilot's seat to permit pilot or co-pilot to immediately shut-off the upper turret oxygen supply in case of emergency.

      2. Installation of Emergency Power Switch on the same panel behind the pilot's seat to permit immediate shut-off of power supply to upper turret in case of emergency.

    7. Sights:

      1. The fact that this Group does not use tracer ammunition, makes the use of the gun sights imperative. In order to use the sights the gunner must understand the theory of sighting, and know how to use them.

        1. Turret Computing Sights will be used and operated in compliance with existing Computing Sight Manuals or Gunner's Information File.

        2. The Ring and Post Sights and Optic Sight will be used in accordance with letters of instructions issued by this Headquarters. The sighting theory reduced and explained in the most simple manner possible in these Letters of Instructions, dealing with the HEWITT Sighting System. The Gunner's Information File also deals with Sighting theory for the Iron and Optic Sights. Each Squadron Gunnery Officer has a supply of these instructions to be issued and explained to each combat gunner. Any difficulties in sighting techniques experienced should immediately be taken up with the Squadron Gunnery Officer.

      2. The Flexible Guns including the chin turret are harmonized for 1,000 yards.

      3. All sights are checked and harmonized every third mission.

    8. Auxiliary Equipment:

      1. Combat Gunners cannot operate at maximum efficiency unless they understand and know how to operate their equipment. This includes radio interphone equipment, and emergency medical supplies. Full information on these subjects can be obtained from current publications, Technical Orders, and Squadron Equipment Officers.


    1. All turrets will search 360 degrees with added emphasis in the area of most likely attack according to present enemy tactics.

    2. Zones of Search for all other guns positions will be maintained in the area covered by the traverse of the particular gun or guns concerned.

    3. The Zone of Search on any given turret depends on only one thing and that is the position of the aircraft in Squadron or Group formation.

    4. It is imperative that all Combat Crew personnel know and understand formation positions and technique, so they will be able to determine the position of their aircraft in any formation, and search accordingly.

    5. The EFFICIENCY of this system depends completely upon the absolute cooperation of each and every gunner. Gunners will maintain an alert search in their assigned areas at all times. Gunners will be in their assigned positions at all times over the enemy territory.


    7. The CLOCK SYSTEM is the approved method of fighter location in Group and will be used. The 360 degree area around any enemy aircraft is divided as indicated below:

    8. Further indication of exact position on enemy aircraft may be made by calling "HI" - "LOW" - or "LEVEL." Example: "Fighter - 11 o'clock - low." This system tends to eliminate unnecessary interphone conversation. In addition gunners should always keep the pilot informed when any enemy aircraft commits himself to a direct attack on the gunner's aircraft. This enables the pilot to take individual evasive action.

By order of the Group Commander
Major, Air Corps
Operations Officer