DC-3 Operations Manual – Fire Detection

DC-3 / C-47 Fire Extinguisher Panel Download the PDF version here: DC-3 Manual Fire Detection Protection PDF

The fire protection system consists of an Edison fire warning system, a CO2 engine fire extinguisher system, a CO2 Janitrol heater fire extinguisher system, and portable dry chemical type hand extinguishers.

Engine fire zone areas

The engine/nacelle area is divided into three zones:

  1.  Zone 1 – Power section – NO detection or protection is provided.
  2.  Zone 2 – Accessory section – detection and protection ARE provided.
  3.  Zone 3 – the wheel well area detection only is provided.

Fire warning system

  1.   The Edison fire warning system consists of a number of thermal detectors throughout Zone 2 and 3 of each nacelle.  In the event of an excessive “Rate of Rise” of temperature in the engine area.  These units operate to illuminate the dual fire warning lights on the Captain’s instrument panel.   Each engine has a separate light.  There is no provision to indicate which zone the fire is in.
  2. Fire warning test switch – a toggle switch is located below the warning lights and tests all circuits simultaneously.

NOTE:  A gradual rise in temperature will not actuate the fire warning system.

 Engine fire extinguishers

 The engine fire extinguisher system consists of a fixed CO2 bottle, engine selector, and a cable operated discharge control.

1.  CO2 bottle and control  – The engine fire extinguisher bottle is located aft of the First Officer’s seat (outboard) and contains 15 pounds of CO2.  The discharge valve is operated by a cable control mounted at the top of the bottle.
2.  Engine selector and CO2 discharge – A control for selecting the engine to which CO2 is to be directed and a pull type T-handle for discharging the CO2 is mounted on a panel recessed into the floor between the pilot’s seats.  The recess has a removable cover that is painted red for proper identification.

NOTE:  Only one (1) discharge is available.  When the bottle discharge handle is pulled discharging cannot be stopped.

3.  Alternate discharge control
A rotating type T-handle is provided at the top of the CO2 bottle as an alternate means of discharging CO2 in the event the pull type T-handle fails to function.
4.  Thermal discharge provision
The bottle is equipped with an overboard discharge line to protect against high pressure caused by thermal expansion.  Discharge through this line blows out a red disc which is flush mounted on the side of the fuselage below the first officer’s window.
5.  Oil and hydraulic fluid shut-off controls
These controls are normally blocked in the ON position by a hinged metal guard and lock ring.  When the metal guard is moved the control handle can be rotated to OFF.  The oil and hydraulic fluid to the appropriate engine will be shut off.

 

Heater fire extinguisher

A four (4) pound hand type CO2 fire extinguisher is securely mounted to the forward bulkhead of the heater compartment and discharges CO2 through a flexible tube directly into the heater jacket surrounding the combustion chamber.

Cabin – cockpit protection

In the event of a cabin or cockpit fire, use the appropriate fire extinguisher located in the cabin and/or cockpit.

OPERATION

CAUTION:  This section presents operating instructions for the fire protection system only.  Operation of the other controls and procedures are essential to the overall effectiveness of fire control. 

 CO2 selection and discharge

  1.  Remove floor panel (red painted cover)
  2. Engine selector – set selector valve to engine desired
  3. T-Handle – Pull (to full limit of travel)

Fire Warning Test

  1.  Hold toggle switch up
  2. Check warning lights – both ON

Heater fire extinguisher

  1.  Pull trigger to discharge

 Portable fire extinguishers

  1.  Remove from bracket
  2. Pull up locking lever to break seal
  3. Squeeze handle to release chemical
  4. Direct stream at base of flames using side to side sweeping motion

LIMITATIONS

  1.  Electrical requirements – operation of the fire detection system require electrical power
  2.  Portable fire extinguishers – fire classification
  • Class A Fire – Wood, cloth, paper, etc.      Use water or dry chemical
  • Class B Fire – Oil, grease, gas, etc.         Use dry chemical DO NOT use water                  or other liquids.
  • Class C Fire – Electrical                                     Use dry chemical DO NOT use water

TROUBLE SHOOTING

  1.  Fire warning light inoperative
  • Remove and check bulbs
  • Check bus voltage – warning system will be inoperative when bus voltage is low
  • Check number 9 circuit breaker in J-box
  1. CO2 discharge control inoperative (on floor panel)
  • Rotate T-handle on top of CO2 bottle behind first officer’s seat

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