gas, when confined to an enclosed area such as a gun
compartment, is highly explosive. The gun gas purge
system cools the barrels and purges gas from the
compartment during gun firing operations.
The gun gas purge system in the F-14 aircraft uses
cold air from the refrigeration system to cool and purge
residual gun gases from the ammunition drum and gun
compartment. The subsystem, activated when gun
firing is initiated, remains active for a 30-second period
after gun firing to ensure that all gases are cooled and
purged.
The F/A-18 gun gas purge system uses engine bleed
air and has an additional gas control provided by a
hydraulically actuated ram-air scavenge door that opens
automatically during gun-firing operations. The gun
gasses are vented through louvers in the lower mold line
of the aircraft fuselage.
REVIEW NUMBER 4
Q1. What chute provides a path from the exit unit to
the adapter assembly?
Q2. What chute provides a path from the transfer unit
to the entrance unit of the drum?
Q3. What is the purpose of the gun gas purge system?
Q4. Describe the difference between the gun gas
purge systems of the F-14 aircraft and the
F/A-18 aircraft.
M61A1 GUN SYSTEM
INSTALLATIONS
LEARNING OBJECTIVE: Identify M61A1
gun system installations to include those used
on the F/A-18 and F-14 aircraft.
M6lA1 gun and ammunition handling system
installations have the same basic components.
However, some components are peculiar to specific
aircraft. These differences are discussed in the
following paragraphs.
F/A-18 GUN SYSTEM INSTALLATION
The F/A-18 M61A1 gun system (fig. 6-14) is
internally mounted in the nose of the aircraft on the
center line. The fired projectiles exit the aircraft through
the gun blast diffuser assembly, located just forward of
the cockpit windscreen. Depending upon the mission
Figure 6-14.—F/A-18 M61A1 gun installation.
6-15
