ATR 42/72-600 Systems Guide — Chapter H: Emergency Equipment

2026-06-23

Chapter H. EMERGENCY EQUIPMENT (FCOM DSC 25, 26, 35)¶

1. EMERGENCY EQUIPMENT SITUATION & CABIN LAYOUT (Page 98)¶

The safety equipment is distributed across the airframe to allow rapid deployment by flight and cabin crews during emergency events.

  AIRCRAFT SAFETY COMPONENT MAPPING
  ┌────────────────────────────────────────────────────────┐
  │ [FLIGHT DECK] ──► Crash Axe, Halon, PBE, Smoke Goggles │
  │                                                        │
  │ [FWD CABIN]   ──► First Aid Kit, Life Jackets, Halon   │
  │                                                        │
  │ [MID CABIN]   ──► Overwing Portable Oxygen Bottles     │
  │                                                        │
  │ [AFT CABIN]   ──► Megaphone, Water Extinguisher, ELT   │
  └────────────────────────────────────────────────────────┘

2. EMERGENCY LIGHTING SYSTEM ARCHITECTURE (Page 99)¶

The internal and external emergency lighting network operates independently of the aircraft's primary generation buses during structural evacuation scenarios.

2.1. Power Delivery and Activation Paths¶

Storage Packs: Powered by self-contained $6\text{V}$ sealed lead-acid battery packs distributed beneath the cabin floor line.
Charging Profiles: When the cockpit EMER EXIT LT switch is set to ARMED, the internal battery packs receive a continuous trickle charge from the essential DC bus network.
Emergency Illumination Tracks: Floor-level escape path markings, internal exit signs, and exterior ground-line illumination arrays activate automatically if the aircraft experiences a total loss of normal DC electrical power.

3. PORTABLE CABIN EMERGENCY LOOSE GEAR (Page 100)¶

A detailed inventory of the portable safety components distributed throughout the aircraft:

First Aid Kit: Packed with standardized medical trauma supplies. Stowed in the forward overhead storage bins for quick cabin attendant access.
Portable Megaphone: Battery-powered unit stowed in the aft cabin partition wall. Used to direct passengers during an evacuation if the primary PA system fails.
Portable Flashlights: Equipped with integrated LED status indicators that flash green to confirm the internal batteries are fully charged and operational.
Crash Axe: Stowed behind the Captain's operating seat structure. Features an insulated handle tested to withstand high-voltage electrical tracking hazards.
Water Fire Extinguisher: Loaded with a water-glycol solution optimized to suppress Class A solid combustibles (paper, fabric, wood) in the passenger cabin.
Halon Fire Extinguisher: Charged with liquefied gas clean agents optimized to suppress Class B liquid fires and Class C electrical avionics fires without short-circuiting adjacent processors.

Chapter H. EMERGENCY EQUIPMENT (CONTINUED)¶

4. OXYGEN SYSTEM CONTROL PANEL & DISPLAY (Page 101)¶

The Oxygen System (ATA 35) is split into two distinct sub-systems: a high-pressure gaseous distribution network for the flight deck crew and individual chemical oxygen generators for the passenger cabin.

4.1. Overhead Crew Oxygen Panel & High-Pressure Tracking¶

Located on the overhead panel network, tracking high-pressure reservoir metrics.

  OXYGEN CONTROL PANEL
  ┌────────────────────────────────────────────────────────┐
  │                         OXYGEN                         │
  │                                                        │
  │                     REGULATOR PRESS                    │
  │                     [ 1400 psi ]                       │
  │                                                        │
  │     CREW SUPPLY                        PAX SUPPLY      │
  │      [  ON   ]                          [ ON BAT ]     │
  │      [ OFF   ]                          [  OFF   ]     │
  └────────────────────────────────────────────────────────┘

CREW SUPPLY Pushbutton:
Released (ON - Flow Allowed): Actuates the main supply valve to vent high-pressure gaseous oxygen out of the oxygen storage cylinder (normally stored at 1800 psi) into the low-pressure crew distribution manifold (regulated down to 60-70 psi).
Depressed (OFF): Isolates the gaseous cylinder. Solenoid closes the supply valve.
REGULATOR PRESS Indicator: Direct mechanical or digital line readout monitoring manifold pressure lines feeding the crew mask housings.
PAX SUPPLY Switch:
NORM / ARMED: System arms the automatic drop sequences.
ON / ON BAT: Manually forces an electrical current down to the cabin mask drop pods, bypassing automatic pressure scheduling barostats to deploy all passenger masks immediately.

4.2. Cockpit Crew Quick-Donning Oxygen Masks¶

Each pilot station is equipped with a quick-donning, face-seal oxygen mask stowed inside an adjacent lateral console storage box.

Inflatable Harness Mechanics: Squeezing the red side handles injects high-pressure air into the structural rubber harness tubes, causing them to expand radically. Releasing the handles deflates the tubes, sealing the harness securely around the pilot's head shape.
Regulator Concentration Modes Matrix:
NORMAL position: Delivers a demand-flow mixture of ambient cabin air and pure oxygen. The oxygen concentration percentage scales up automatically as cabin altitude climbs.
100% position: Supplies continuous 100% pure oxygen on demand to safeguard against toxic smoke or chemical fumes.
EMERGENCY position: Rotates the selector knob to provide positive-pressure continuous 100% pure oxygen flow. This purges the interior mask cavity and forces smoke out of the pilot's field of vision (must be coupled with smoke goggles).

5. PASSENGER & PORTABLE OXYGEN EQUIPMENT (Page 102)¶

5.1. Passenger Chemical Oxygen Networks¶

Deployment Trigger Rules: The passenger cabin mask drop containers release automatically via a barometric pressure switch if the internal cabin altitude breaches a critical structural limit threshold (> 14,000 ft).
Generation Properties: Actuation relies on solid chemical sodium chlorate core candles installed inside overhead passenger service units (PSUs). Pulling a deployed mask down generates localized friction, triggering an exothermic chemical reaction that produces breathable oxygen continuously for approximately 15 minutes.
Warning: The chemical candles generate extreme surface heat (> 260°C) during active deployment. They cannot be deactivated once the chemical breakdown loop is initiated.

5.2. Protective Breathing Equipment (PBE) & Portable Units¶

PBE / Smoke Hoods: Self-contained breathing enclosures containing a solid chemical oxygen source. Stowed adjacent to fire extinguishers to provide 15 minutes of independent breathing protection during active firefighting actions.
Portable Oxygen Bottles: High-pressure manual cylinders equipped with constant-flow mask hookups. Used by cabin crew members to maintain mobility during structural decompression profiles or to provide first-aid treatment to passengers.