PYLON OVERHEAT DETECTION
There are four 250° F over-temperature
switches for each engine pneumatic system
(Figure 9-4). This includes two in each pylon
and two on each side of the tailcone adjacent
to the pylons. If the temperature exceeds 250°
F at any one of the sensor locations, a red
“L/R ENG PYLON OVHT” message will ap-
pear on the CAS (Table 9-2). This message,
which indicates a bleed-air leak may have oc-
curred in the pylon or just inside of the tail-
cone, is also accompanied by the illumination
of a red “L/R ENG PYLON OVHT” annun-
ciator on the CWP (Figure 9-6).
BLEED-AIR DUCT OVERHEAT
DETECTION
A bleed-air over-temperature switch is in-
stalled in the bleed-air supply duct just down-
stream of the HP SOV on each side of the
tailcone (Figure 9-4). If the bleed-air in the
duct exceeds 700° F, an amber “L or R BLEED
OVHT” message will be posted on the CAS
(Table 9-2).
TAILCONE LEAK DETECTION
The bleed-air leak detection system monitors
tailcone ducts to alert the crew of a bleed-air
duct or an anti-ice duct leak.
Detection of a bleed-air leak in the tailcone
is through heat-sensing elements routed near
the ducts. The elements are the same loop-type
elements as used for engine fire detection,
but are designed to trip the detection system
at 255° F.
Left and right sensing elements monitor for
bleed-air leaks in the ducts from the HP SOVs
on each side, inboard to the PACK Bi-Level
PRSOV (Figure 9-4). If a leak occurs between
either the HP SOV and the ECS check valve
down stream of it, the corresponding red “L
or R BLEED AIR LEAK” message will be
posted on the CAS (Table 9-2 and Figure 9-
6). Also, the corresponding red “L or R
BLEED AIR LEAK” annunciator will be il-
luminated on the CWP.
If a bleed-air leak is detected between either
ECS check valve and the PACK Bi-Level
PRSOV, a red “LR BLEED AIR LEAK” mes-
sage will be posted on the CAS and both the
“L” and “R” BLEED AIR LEAK annuncia-
tors will be illuminated on the CWP (Table 9-
2 and Figure 9-6). The AFM provides separate
procedures for cases when a single BLEED
AIR LEAK is annunciated and when both L
and R BLEED AIR LEAK annunciators are
illuminated.
The bleed-air duct leak detection sensors, anti-
icing duct leak sensors and the engine fire de-
tect sensors are all tested together with the
FIRE DET position on the system test knob.
9-9
FOR TRAINING PURPOSES ONLY
LEARJET 45 PILOT TRAINING MANUAL
FlightSafety
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