FIRE PROTECTION
Description
Aircraft Operations Manual
7.1
PAGE
1
Apr 01/15
1.
GENERAL
The fire protection system provides:
−
Fire detection of the engines plus an extinguisher
system.
−
Detector failure system.
−
Tail pipe overheat detection.
−
Smoke detection for the avionics, lavatory and
cargo compartments.
−
Extinguisher system for the cargo compartment
in standard version aircraft.
2.
MAIN COMPONENTS AND SUBSYSTEMS
2.1
Engine fire protection (Fig. 1 and Fig. 2)
Detection of fire or overheat in the engine nacelle
fire zone is ensured by a single continuous loop
detection circuit below each engine.
There is one control unit for each engine. The con-
trol unit continuously monitors the resistance value
in the loop. If a preset resistance value indicating a
fire is reached, the unit will activate the fire warning
system.
Too quick resistance change in the loop, however,
will not result in a fire warning but in a detector fail-
ure indication, indicating that the loop has been me-
chanically short circuited and is unreliable.
For a fire, the following warnings will be given:
−
Fire bell
−
MASTER WARNING and
L/R ENG FIRE (CWP) light and
L/R ENG fire handle light (red).
Pressing either of the master warning lights or pull-
ing the respective fire handle will extinguish both
master warning lights, silence the fire bell and
change the flashing L/R ENG FIRE light on CWP to
steady. The L/R ENG FIRE light and L/R ENG fire
handle light remains on as long as the warned
condition exists.
A detector failure gives the following indications:
−
MASTER CAUTION and
L/R FIRE DET FAIL (CWP) light.
Pressing either of the master caution lights will ex-
tinguish both master caution lights and change the
flashing L/R FIRE DET FAIL light on CWP to
steady. The CWP light remains on as long as the
caution condition exists.
The engine fire warning and detector failure system
can be tested with two switches on the TEST 1
panel. Using these switches, both an engine fire
and a loop short circuit are simulated with correct
warning indications both aurally and visually.
Pulling a fire handle will have the following result:
−
Engine fuel shutoff valve is closed.
−
Engine bleed air pressure regulator valve is
closed.
−
Start
−
Gen field relay is open.
−
Fire bell is silenced.
−
Master warning is reset, indicated by the master
warning lights going out.
−
Both main and reserve extinguisher squibs for
the engine are armed.
−
Right fire handle shuts off the power supply to
prop. brake. Hydraulic lock valves will keep the
brake engaged and PROP BRAKE light and
MASTER WARNINGS come on.
There is one extinguisher bottle installed in each
engine nacelle equipment compartment. Extinguish-
ing agent is Halon 1301.
Each bottle can be discharged into the fire zone of
the nacelle where it is installed or it can be dis-
charged and routed to the nacelle on the other wing
to serve as reserve for its extinguisher bottle, e.g.
the left FIRE EXTG switch discharges the left extin-
guisher into the left engine if the left fire handle has
been pulled, and into the right engine if the right fire
handle has been pulled.
The released extinguishant is discharged into the
engine fire zone area through a manifold optimizing
distribution to the spray nozzles.
The armed extinguisher squib (explosive cartridge)
is activated by the respective bottle’s FIRE EXTG
switch located adjacent to its fire handle.
2.2
Tail pipe overtemperature (Fig. 1)
Applicable to a/c without mod. 3400/3401
There are three overtemperature detectors installed
around each engine tail pipe. The detectors are
wired in parallel so that an overheat signal from a