TM 1-1520-238-10
2-73
b. 95% Cold Start Switch.
A spring-loaded 95%
switch allows the pilot to delay APU PTO clutch engage-
ment during APU starts at temperatures below 0 F (–18
C). Delaying PTO clutch engagement until the APU is at
95% operating speed allows successful engagement in a
cold weather environment. The switch is spring-loaded to
the NORM position and must be held in the 95% position
when used. PTO clutch engagement is inhibited until the
switch is released and returned to the NORM position.
The switch is used with the APU ON advisory light that in-
dicates the APU is operating at or above 95% speed.
c. APU Fire Warning and Extinguishing Con-
trol.
APU fire warning is provided by a warning light in
the FIRE APU PULL handle and a FIRE APU warning
light on the pilot and CPG MASTER CAUTION panels.
Section II of this chapter describes emergency equipment
operation. An APU fire can be extinguished by pulling the
pilot FIRE APU PULL handle and placing the FIRE BTL
selector switch either to PRI (primary) or RES (reserve).
The fire test portion of the panel is discussed in detail in
Section II of this chapter.
BTL DISCHARGE
APU
PRI
DISCH
RES
DISCH
FIRE TEST
DET
2
1
OFF
START
RUN
OFF
95%
NORM
PRI
RES
FIRE BTL
M01 319
Figure 2-41.
APU Control Panel
