MAINTENANCE AND TESTING

LEARNING OBJECTIVE: Identify maintenance and testing procedures at the organizational and intermediate levels.

The maintenance and testing responsibilities of an M61A1 gun installation are distributed evenly between the organizational and intermediate levels of maintenance. The basic responsibilities of these two levels of maintenance are discussed in the following paragraphs.

ORGANIZATIONAL MAINTENANCE

Organizational maintenance includes servicing (loading and unloading), preflight, postflight, minor periodic maintenance, malfunction troubleshooting, and removal and installation of components on the aircraft. Also, maintenance of the aircraft system and controls must be included in the AO's organizational responsibilities.

The gun firing record or log is kept at this level. The cumulative total of rounds fired is the basis for most of the maintenance. The number of rounds fired per firing flight is obtained from a counter located within the aircraft. For record accuracy, each time the gun installation is loaded, the counter must be reset (usually to zero) according to the instructions applicable to the aircraft. The two primary tasks that depend upon the round interval (rounds fired) are (1) torquing the two forward front track bolts (30,000 rounds), and (2) changing the breech-bolt assemblies (15,000 rounds).

Organizational responsibilities are not included in NAVAIR 11-95M61A1-1 or the NAVAIR 11-95M6lA1-2. Organizational responsibilities are outlined in MRCs, aircraft MIMs, and aircraft loading manuals.

If a component is being removed for sudden stoppage (jam) maintenance, be careful and take extra precautions. Loose propellant powder from ruptured cartridge cases may be scattered about the gun compartment. This creates an extremely hazardous situation. The loose powder must be removed in a RADHAZ-free environment before you begin to remove a component.

INTERMEDIATE MAINTENANCE

Intermediate maintenance responsibilities are tasks associated with repair or replacement of unserviceable or damaged assemblies, components, or parts of the gun installation that do not require the special maintenance facilities of an overhaul depot. When a gun reaches a round interval of 120,000 rounds fired or requires major repair or alteration, it is sent to a depot-level maintenance activity. The ammunition handling and gun drive system maintenance procedures are identical at both the intermediate- and depot-maintenance levels (with one exception, the depot level removes bearings); therefore, such maintenance is generally performed at the intermediate level. Intermediate maintenance may be divided into two categories-scheduled and unscheduled.

Scheduled maintenance includes inspecting, disassembling, replacing parts, lubricating, assembling, and functionally checking components based on the round interval specified in technical manuals. Scheduled gun maintenance begins at 15,000 rounds and proceeds through various interval states for different parts replacement up to the 120,000-round overhaul interval. Scheduled maintenance for the handling and drive system is set at an interval of 30,000 rounds.

SAFETY PRECAUTIONS

LEARNING OBJECTIVE: Identify safety precautions to follow when working with the M61A1 gun.

The weapons systems described in this chapter are safe systems. Live rounds are isolated from the firing circuits except when the gun system is deliberately being fired. The gun system is RADHAZ safe and completely shielded from radiation fields. The gun is charged and cleared in flight, so the aircraft can takeoff and land without live rounds in the firing position. Although the sole purpose of all ordnance is to destroy an enemy, the equipment cannot identify friend from foe. Therefore, all safety precautions must be followed at all times.

The following general safety precautions are not related to any specific equipment or procedure. These precautions are recommended safety precautions that all personnel should follow when operating and maintaining equipment.

All persons who supervise or perform work in connection with ammunition handling should be familiar with the United States Ordnance Safety Precautions, NAVSEA OP 3347. When test firing is conducted using live ammunition, observe all existing range regulations.

Before undertaking any operation for which a checkoff list exists, the checkoff list is read so all personnel know what to do.

When provided, always use safety devices to prevent accidents. Keep safety devices in good operating order at all times.

Do not make changes, modifications, or additions to a weapons system without prior approval and authorization from the appropriate authority.

A hazardous condition exists if a gun malfunction occurs and there is anything in line with the gun muzzle.

Observe area clearance requirements during maintenance periods.

Electrically primed ammunition can be fired by percussion. NEVER cycle live ammunition through a gun for testing purposes.

The explosive elements in electric primers are highly sensitive to static electricity. Make sure the primer button does not come into contact with the human body.

Observe fire regulations and maintain good ventilation when using cleaning solvents and other volatile maintenance materials.

Before performing maintenance actions involving pneumatic or hydraulic pressurized components, ensure that all pressure is removed and the component is in the safest possible condition.