Gunnery Officer Gunnery Officer INFORMATION SHEET
PRE-FIRE CHECKS
Information Sheet Number: 1.13
INTRODUCTION
To ensure guns fire when the trigger is pulled, system operability checks are required IAW PMS in a peacetime environment. These checks take into consideration gun safety, durability, and optimum firing performance. This lesson discusses the time frames of completion and a brief overview of tasks required.
REFERENCES
(a) NAVSEA OP3347 Ordnance Safety Precautions
(b) MRC 7111 R-1
INFORMATION
A. GUN FIRING REQUIREMENTS
1. Before firing any gun in time of peace, the prescribed pre-fire checkoff list for that gun must be completed.
2. Under combat conditions, pre-fire and firing precautions apply as operating time permits.
3. The Combat Systems Officer is responsible to the Commanding Officer for the completion of pre-fire checks.
4. The Gunnery Officer is responsible for reporting to the Combat Systems Officer that all pre-fire checks have been completed. This written report details the Gunnery Officer's personal verification of required actions.
B. PRE-FIRE MAINTENANCE REQUIREMENTS
1. Pre-fire checks pertain to the preparatory requirements necessary for making a battery ready for a firing exercise.
a. The majority of the checks are completed 24 hours prior to the exercise.
b. Once completed, they require department head signature and CO approval.
2. In all cases, careful attention must be paid to pre-fire checks included in the PMS, to ensure that the MRC requirements match those found on the checkoff list.
3. The following summarizes PMS pre-fire checks for 5"/54 guns:
a. Inspect gun equipment for binding, broken, loose, and missing parts.
(1) A general housekeeping survey to prevent:
(a) Misfire condition during exercises
(b) Catastrophic accidents
b. Check gun bore with gun bore gage.
(1) Manually open the breechblock and, using the air motor, position gun barrel to a convenient angle for passing the bore gage.
(2) Assemble sectioned bore gage.
(3) Insert the bore gage into the muzzle and pass the bore gage through the entire length of the gun bore to ensure it is clear of any obstructions.
The technician must immediately notify the maintenance group supervisor if the bore gage will not pass through gun bore.
(4) Manually unlatch and close the breechblock.
c. Test normal and emergency firing circuits and firing cut out zones.
(1) Insert test case without primer into the breech and close.
(2) Establish communications with safety observer and weapons control.
(3) Ensure personnel are in safe area before activating gun mount.
Personnel are subject to extensive injury if they are in swing circle or weather shield while gun is in motion.
(4) Using local control handwheels, train and elevate mount into safe firing zone and verify firing zone clear.
(5) Test remote firing circuit by closing firing key at the Weapons Control Center (WCC) and train and elevate mount into several unsafe firing zones and verify "FIRING ZONE NOT CLEAR" and "MISFIRE FIRING INTERLOCKS CLOSED" lamps are lit.
(6) Open firing key and train and elevate gun to a safe firing bearing.
(7) Manually raise breechblock, insert primer into test case and fire primer as a final test of the remote firing circuit.
(8) Test local and emergency firing circuits in same fashion as the remote firing test, by inserting and firing primers.
(9) After firing primers the gun barrel must be cleaned of residue.
d. Check fuse setter operation
(1) In "Step Load Mode," position a dummy round equipped with a test fuse set for 100 +/-10 inch-lbs of torque at the transfer station.
(a) "Step Load Mode" allows for positive control of the gun mount from the EP2 panel one process at a time.
(b) The test fuse has an adjustable torque setting to allow for a performance check on fuse setter operation.
(2) Open upper hoist access door and position load selection switch to auto load and ensure door is then closed.
(3) Verify the NORMAL SELECT-LOADER LOADING MODE pushbutton is lit.
(4) Request from weapons control a remote 25.7 second fuse position order.
(5) Fuse setter will extend and index. Verify the 25.7 second fuse reading at the indicator dial on top of the fuse setter.
(6) Request from weapons control a 0.12 second fuse position order and re-verify position.
(7) Depress the load order continuous pushbutton and request from weapons control a remote fuse order in increments of .3 to 1.0 seconds. Fuse setter will retract between 0.8 and 1 seconds.
(8) Depress transfer station EJECTOR-EJECT pushbutton and remove dummy round.
e. Ensure gas ejector air pressure gage indicates between 165 and 185 PSI.
f. Activate gun mount and open and close the breechblock in step control to activate air pressure of the gas ejection system.
g. Measure the duration of the air blast exhausting at the right side of the slide. Repeat as often as necessary to obtain an accurate reading.
(1) Verify that the duration of the blast is between 1 and 2 seconds.
h. An officer shall witness the inspection and filling of recoil/counterrecoil systems and verify the gun is in battery.
i. Check the differential piston rod extension.
(1) Ensure empty case tray is in the raised position.
(2) At the EP2 panel use local control handwheels and position the gun barrel at 2000 minutes of elevation.
(3) Depress all motor stop buttons.
(4) Ensure safety link is connected.
(5) Measure differential pressure rod extension from the face of the cylinder seal to the end of piston rod.
(6) Always refill counterrecoil cylinder seal before piston rod extends more than 7 inches from the seal housing.
j. Check counterrecoil nitrogen pressure.
(1) At counterrecoil cylinders, read thermometer and record ambient temperature.
(2) Verify gage indication is within 20 PSI of correct nitrogen pressure. Notify maintenance group supervisor if nitrogen pressure is abnormal or unit shows signs of leakage.
(3) If gage pressure is 20 PSI less than correct nitrogen pressure, charge counterrecoil cylinders IAW PMS.
k. Check empty case tray buffer indicator extension.
(1) Verify that the buffer indicator does not protrude more than .125 inches when fluid temperature is between 60 and 80 deg F.
(2) Notify maintenance group supervisor if oil level is low or unit shows any indication of leakage.
(3) If the buffer indicator protrudes more than .125 inches, replenish oil IAW PMS.
l. Disconnect safety link if firing mission is to follow.
m. If firing mission does not follow, return equipment to readiness condition.
8. A knowledgeable commissioned officer or warrant officer shall be present and verify specific tests and inspections required by the checkoff list prior to presenting the completed checkoff list to the Commanding Officer or Officer-In-Charge.
C. GUNNERY OFFICER VERIFICATIONS
1. The immediate surrounding area of the gun shall be free of flammable materials and obstructions.
a. Remove excess hydraulic oil.
b. Painting materials and lubricants are not to be stored within gun enclosure.
c. Ensure areas are secured for sea to prevent missile hazards.
d. Ensure ship preparations are complete.
(1) Lay out fire hoses.
(2) Lower antennas, if required.
(3) Drop helo nets and life lines.
2. Verify recoil and counterrecoil systems status.
a. Check recoil hydraulic fluid levels.
b. Check nitrogen pressure for counterrecoil system.
3. Remove tompions.
a. Removal is required to check bore inspections.
b. Primers cannot be fired prior to removal.
c. Do not assume they have been removed, go look.
4. Check counter-recoil differential piston protrusion. Piston protrusion must be less than 7 inches. If greater than 7 inches, the piston must be refilled and pressurized.
5. Ensure salvo latch is operational.
a. This device prevents loading projectiles in a full breech.
6. Verify firing cutouts.
7. Verify synchronization of gun orders.
8. Test gun train warning alarm.
9. Ensure safety link is removed.
a. The safety link keeps the gun in battery in the event of a recoil system failure while the gun is not in use.
b. The link must be removed prior to firing to prevent damage to the gun.
10. Ensure the correct projectiles are used.
D. PERSONNEL SAFETY
1. Manned gun systems
a. Ensure that all personnel observe all mechanical, electrical, and hydraulic general and specific safety precautions as outlined in the applicable Operating Procedures (OPs) and MRCs.
2. Unmanned gun system
a. Prior to gunnery exercises, the Weapons or Gunnery Officer shall ensure that no personnel are in an unmanned gun mount or within the mount's safety circle.
b. Ensure all non-essential items are removed.
c. Personnel shall not enter an unmanned gun mount for maintenance or other reasons unless ordered to do so by Gun Control.
(1) Upon leaving and securing a mount, an "all clear" report shall be made to the Gun Control Officer.