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BOEING 727 WARNING & EMERGENCY SYSTEMS

 

Warning Horns...

Ground Proximity Warning System...

The GPWS alerts the flight crew should any of the following occur:

Crew Oxygen...

Each crew station has an oxygen regulator which must be ON for any oxygen to flow through the regulator.  100% mode will deliver undiluted oxygen when the user inhales.  The NORMAL position will provide a mixture of both cabin air and oxygen on demand based the 5000-foot equivalent.  The emergency switch will deliver 100% oxygen in a continuous flow regardless of the position of the oxygen switch.

Typical setup on the crew's oxygen panels allows crew members to don oxygen masks and receive 100% oxygen without any other action.

Passenger Oxygen...

The passenger oxygen system can be activated in three ways:

  1. Electrically - when a switch on the engineer's panel is moved to ON.
  2. Mechanically - when a T-handle is used to open the bottle valves.
  3. Pneumatically - when cabin altitude exceeds approximately 14,000 feet.

The passenger cabin is provided with portable oxygen bottles for use by flight attendants or for emergency medical use. These bottles deliver 100% continuous oxygen at a rate of 2 or 4 liters per minute. The high-flow rate is for medical use only. (The bottle contains 311 liters of oxygen.)

 

Portable Fire Extinguishers...

The 727 carries three types of portable fire extinguishers.  They include:

  1. CO2 Foam -- primarily for electrical fires.
  2. Dry Chemical -- used in galleys.
  3. Water -- used for smoldering-type fires.

 

Built-In Fire Protection...

The fire switches panel has four warning lights which will illuminate should there be a fire in any of the engines or wheel wells. A bell also provides an aural warning. Two freon gas bottles serve as an extinguishing agent for the engines.

 

Fire Detection...

Each engine on the 727 has two independent fire detection circuits (A and B) which sense temperature.  Once the temperature reaches the specified value, the corresponding fire light illuminates and the warning bell sounds.

Wheel wells have a "continuous loop" fire detection system. As heat on this wire increases, electrical resistance decreases, which in turn causes the WHEEL WELL fire light to illuminate and the fire bell to ring.

The fire warning bell does have a cutout switch, but this switch also silences the APU cockpit fire bell and external fire horn.

The APU also has a freon gas bottle for fire extinguishing.  A fire detected in the APU will illuminate the APU fire light and ring the cockpit bell.  As previously stated, there is also an external warning horn to alert ground crew should the fire start on the ground.  The horn is located in the nose wheel well.  The APU has an automatic fire shutdown switch which will automatically close the fuel valve or may be closed manually by closing the APU fuel valve.

 

Emergency Evacuation: Exit Lights & Emergency Exits...

When the emergency exit lights are armed, they will illuminate automatically with loss of AC essential power.

During an emergency evacuation, the emergency exit light switch should be ON and the battery switch OFF.

Emergency exits for passengers include the forward entry and galley door, four overwing emergency exits and possibly the aft airstair door depending on aircraft attitude. All of these doors can be opened from both inside and outside the aircraft.

The forward entry and galley doors are provided with inflatable escape slides. These slides will deploy automatically (but not inflate) when the door is opened IF the escape slide bar is attached to the door brackets.

As there are no escape slides on the overwing exits, flaps have to be fully extended for passenger evacuation.  Overwing exits do, however, have an escape rope to aid passengers.

Overwing exits open INWARD. To assist in opening these doors during an emergency evacuation, the outflow valve should be open.