Emergency systems in aircraft help prevent and protect against accidents and their effects. They include alarm and warning systems to alert pilots of issues, fire detection and suppression systems to quickly address fires, and fuel explosion suppression to prevent tank detonations. Additional systems provide emergency power, oxygen, reinforced seating, evacuation slides, and flight recorders to investigate accidents. These systems have improved aircraft safety and survivor rates over time.

1. Emergency Systems in
Aircraft
Cian McCarthy
Alex Yourell

2. Introduction
 2 main types of Emergency systems in aircraft:
1. Prevention 2. Protection
• Anti-skid braking
• Alarm and Warning
• Fire detection and suppression
• Fuel system explosion and
suppression
• Emergency power generation
• Emergency oxygen supply
• Anti-crash seats and interiors
• Occupant ejection
• Crash switch
• Flight Recorder

3. Alarm and Warning Systems
Many different types of alarms and warning signals depending on the aircraft.
One single (Caution) panel:
All alarm warning lights +
Displays
OR
Multi
Function
Panel –
Modern
Aircraft
• Most alarm warnings – Flashing lamp and acoustic
signal
• Light + Signal activated when corresponding sensor
detects an emergency condidtion (fire, smoke, etc.)
Normal Reaction by pilot: Press
button to silence acoustic signal
and steady flashing light –
Appropriate measurements.
Multi-
Function
Advantage –
Suggests
procedure
for pilot

4. Fire Detection and Suppression
Fire is the
main cause
of death in
aircraft
accidents
Cabin
Fuel Tanks
Deteriorate
Structural
resistance
Fire detection:
1. Fire detectors – Based
on heat and temp
2. Smoke detectors –
Opacity/particles
• Cabin areas – smoke alarm
• Other pressurised areas
Sensors
detect fire
within 60
seconds –
false alarms
Most typical + hazardous
area for a fire – Engine
compartment
 High temp area
 Many flammable fluids
present
 False alarm more
severe
• Discrete – Thermocouples/Bi-metallic sensors
• Continuous – Coaxial cable routed around engine
compartment

5. Signals from sensors sent to control panel and then to the cockpit.
Wired
Transmission
• Inconvenient
to install +
maintain
• More reliable
Wireless
Transmission
• Installation +
Maintenance
time
• Signal
spreading
Cabin fire suppression
Fire suppression in cargo bays,
engines etc. :
• Fire extinguisher component
• Located in many areas of aircraft
• Remotely controlled
• Pressurised fluid
• Fluid canalised to nacelle, bay
etc.

6. Fuel System Explosion Suppression
1. Fuel pressurisation with
inert gas:
 Fuel tank pressurised with
nitrogen
 Dual advantage making pump
system more efficient +
introducing an inert gas.
2. Introduction of reticulating
foam:
 Reticulating foam introduced into
tank.
 Fills entire tank & divides fuel +
vapour volumes into small cells
 This fragmentation reduces speed
of the flame
 Reduction of fuel outflow after tank
leakage & reduction of fuel
surging.
Fuel
Tank
Vapour fuel
Liquid fuel
Electrical
Malfunction/Lightning
Penetration of
munitions (military)

7. Emergency Power Generation
• Electrical & hydraulic
power generation
- Air can be bled from any engine.
- Electrical generators connected to all engine gear boxes.
- Hydraulic pumps installed (operated by gearboxes +
electric motors)
AuxiliaryPowerUnitActivation
• Air bled
from the
APU
compressor
• Gearbox
drives both
hydraulic
pumps +
electrical
generators
• APU slow
to start -
HydrazineEmergencyPowerUnit
• An EPU is
a turbine -
Hydrazine
• Gases
canalised to
turbine
• Turbine
drives
electrical
generator
and/or
hydraulic
pump
• Short
period of
time
BatteryOperatedHydraulicPumps
• Third
method
based on
hydraulic
pump
operation
by DC
electrical
motors
• Supplied
by an
emergency
battery
• Very
common
method
relying on
kinetic
energy
• Extending
outboard a
RAT –
driven by
external air
• Turbine
operates
generator/
pump to
power
essential
controls
Hydraulic &
electrical
power
generators:
1. APU
2. HEPU
3. Hydraulic
pumps
4. RAT
RamAirTurbine

8. Emergency oxygen system
 Pressurised commercial vehicles
 Liquid pressurised bottles
 Purpose and location?
So how does the emergency oxygen system work?
About to
die….but
first let me
take a
selfie
 Pressurised commercial vehicles
 Liquid pressurised bottles
 Purpose and location?

9. Anti-crash seats and interiors
seats and restraint systems have increased accident survivability
how?
Surviving impact
Surviving a fire
From To

10. Occupant Escape
Occupant entrapment inside a crashed vehicle implies a risk of exposure to post-
crash fire and toxins.
Making evacuation easier
 Air host
 Study of seat layout
 Evacuation before crash
 Lever initiates ejection
 Ejecting can be dangerous

11. Emergency Escape slide
 Situated on bottom half of door
 Carbon fibre pressure cap
 Light weight & sizeable
 Doors open while ‘armed’ to release slide
 Pin is released, releasing compressed air
 Cabin crew may inflate
Speed of inflation: 1960s 25s
2015 6s

12. Flight Recorders
 Recorded time > 25hours;
 Fire resistance 1100°C for 30
minutes;
 Water pressure resistance 7000m;
 Operation after crash: 30 minutes
Flight data & voice recordings are not a system of reducing occupant injuries
However
Their use in the long term has contributed in a better understanding of aircraft accidents