- Doors & Windows, Luggage/Cargo Compartments & Restraints, Seats & Harnesses, Aircraft Ventilation, Heating & Contamination

Doors & Windows Purpose

Pax, Pilot, Cargo, Maintenance

Doors

Stressed skin and often include a window

What are Windows

Round, elliptical, square

Glass, Perspex (acrylic), polycarbonate, or combination

Light aircraft rarely have glass

Doors & Exits -

- Doors & emergency exits are operated by handles connected to a system of push rods and catches, which engage in the surrounding structure

- Doors usually have a "locked" position, which must be engaged before flight, always visually check locks are engaged

- Emergency exits should be checked on pre-flight for the witness or safety wire which determines it is locked

Windows

- Windows can be Plug-In (usually the case for pressurised aircraft cabins) or Bolt-In

- Bolt-In windows can be designed to be load-carrying

Operational Aspects of windows

Some aircraft are permitted to be operated with doors opened or removed:

e.g. skydiving, photography

Flight manual should first be consulted to determine if it can be done. If not referenced, assume not permissible

Structure around door opening should be reinforced due to the change in load path

Inspect door locks and seals

Inspect deformation/corrosion, especially if structural components are made from aluminium alloys

Luggage/Cargo Compartments & Restraints

Separate compartments or restraints for cargo & luggage:

To ensure that there is no flight safety compromising movement of that cargo.

- All loose articles should be restrained on-board an aircraft

- Even better if stowed in a separate compartment from the cabin

Separate cargo areas not only contain cargo but will contain a fire.

Restraints should always be anchored to a major part of the airframe structure.

This will be determined during design/manufacture and decision will not lie with the pilot

Large transports employ elaborate mechanised restraint systems for standard sized cargo containers, pallets, etc

Serviceability checks -

Check webbing for missing, broken or badly frayed straps

Straps should never be fitted in a twisted state

Fittings should be checked for missing components & parts

Ensure fittings engage properly in receptacles

Seats & Harnesses

Harnesses are for restraining the occupants

Seats - usually metal framework with squabs attached and covered with fabric

Can be fixed or adjustable, crew seats are usually adjustable

Harnesses can be just a lap strap, a lap and diagonal or full double shoulder harness

- Double shoulder may have negative "G" strap included

- Seats and harnesses are secured with the same considerations for serviceability checks as cargo restraints

- Loads should not be carried on seats, however if unavoidable they should not exceed the weight considerations for which the seat was designed, and must be adequately secured by the seat harness

Ventilation

- Light A/C have ventilation systems fitted primarily to maintain a flow of fresh air through the cabin

- Like a motor car system, based on ram air where a controllable flap can be opened to the airflow.

- Could be a stand-alone system or could be an integral part of the heating system.

- The intake will be positioned forward of the cabin, a flap or door will be controlled by a selector on the instrument panel which uses a cable to actuate the flap or door. Electric motors may be used when combined with a heating system

- Air is ducted to the cabin via adjustable louvers, and exits via vents in the rear of the cabin.

Serviceability

Not much to go wrong with these systems:

Broken cable

Doors/flaps seized due to inactivity

Blower motors fail

Flaps can usually be viewed from the exterior of he aircraft to check for serviceability

If not supported by a heating system, outside air temperature may be too low for the system to be used when flying.

Precaution:

If it becomes necessary to use alternate static pressure source, ventilation system should be shut off (Refer flight manual)

This is due to such systems are capable of raising the cabin pressure altitude by several hundred feet so altimeter could produce false altitude information

Ventilation - Static Air

Precaution:

Blower should not be used during TO in case of a crash. Why?

Blow smoke, fumes and fire into the cockpit or cabin

Heating

For a comfortable environment

Small A/C typically use an exhaust shroud heater:

- Heated air enters cabin though valve in firewall

- Economical to use since requires no additional energy

- Possibility of CO poisoning if exhaust system cracked

- Proper inspection is important

Light/medium twins may use a combustion heater:

- Air & Fuel are burned in the combustion chamber

- Ventilation air passes over the outside of the combustion chamber, heats up and is passed into the cabin

Safety features include:

- Duct limit switch

- Overheat switch

- Vent air pressure > combustion gas pressure

Combustion Heater

Electric heaters can supplement the heating system, when A/C is on ground

As mentioned medium sized aircraft use exhaust heat augmentation systems

Large turbine-powered aircraft typically use compressor bleed air for heating

Contamination

Carbon Monoxide - CO (from engine)

- Detectors are generally used to detect deadly levels of this gas

- Indicator (badge on instrument panel) containing tablet which changes colour from tan to black

- Portable testers containing yellow silica gel impregnated with a catalyst which turns grey/black with CO present

- Permanently fitted electronic detector

- Baggage or cargo may include dangerous goods and can produce poisonous gas if burnt

- Structural corrosion can occur from contaminates