Lights

Question 1

Electric light sources

Answer 1

Types of light sources:

° Incandescent Light - light is produced by temperature radiation, it uses tungsten filament, it is encased in a gas filled bulb.

° Halogen Incandescent lamps - it is the improved incandescent lamp. It has 50% more effectiveness and it has a longer lifetime because it is filled with halogen gas.

° Gas discharge lamp - gas atoms generate light when ionized by an electric current

Application of gas discharge lamps:
-Cold start fluorescent lamps
-Direct start fluorescent lamps
-Strobe lights

° High intensity discharge lamp - it is a gas discharge lamp type. It produces light when gas is heated.

° Light Emitting Diode - it is a special type of semiconductor diode. It releases energy in the form of photons. The wavelength of the light and its color, depends on the material of the diode.

Materials of LEDs are:
-Aluminum Gallium Arsenide for red
-Gallium Nitride for green
-Silicon Carbide for blue
-Combined all basic colors for white

Question 2

External lighting

Answer 2

Its purpose is to allow the aircraft to be clearly visible from outside during operation in the air and on the ground as well as to provide the crew with sufficient view of the outside world to operate safely

Question 3

External light

Answer 3

• Obstruction light - give a visual indication of the aircraft wingtip position during ground operation

• Navigation light - is to mark the aircraft position and give an indication of its orientation. Red for left side, Green for right side, and white rear side of the aircraft.

• Anti Collision Light - help to mark the aircraft position as a joint function with navigation lights. It gives a flashing effect.

• Strobe light - it provides high intensity flash by using a set of capacitors. The typical flashing frequency is 60-70 flashes per minute.
• Beacon light - are fitted to aircraft near the center of the fuselage. Located at the top and bottom of the fuselage. It serves as a safety warning to ground personnel that the engines are being operated.

• Taxi Camera Light

• Landing light - provide sufficient illumination to allow the flight crew to see the area ahead of the aircraft during final stages of landing

• Taxi light- illuminate the area around the front of the aircraft.

• Wing & Engine Scan light (Ice inspection lights) - used to provide sufficient illumination for the crew to examine the area for ice formation

• Logo lights- it is installed on trimmable horizontal stabilizer to light the airline logo. The logo lights automatically come on during taxiing, take-off, approach, and landing phases when the logo switch is set to AUTO.

Question 4

Emergency Lighting

Answer 4

• It is required by the law that an aircraft shall be equipped with a lighting system that provides illumination in the event of an emergency evacuation to assist the passengers and the crew in leaving the aircraft.

-designed to provide sufficient illumination to the cabin, to identify the emergency exit areas and to ensure safe and quick escape

• Lower illumination level than normal cabin lighting as the power source is a battery
• powered by their own Ni Cad battery packs
• Emergency Power Supply Units (EPSUs) are the heart of the emergency lighting system

Emergency lights comprise:

• the cabin ceiling emergency lights
• the staircase emergency lights
• the cockpit way lights
• the floor path marking system
• the emergency slide lights
• the emergency door lights
• the exit signs.

Question 5

Internal Lighting

Answer 5

• It enable the flight crew to operate the aircraft safely, the cabin crew to carry out their duties effectively and the passenger to feel comfortable during normal aircraft operation

Internal lighting system functions:
* Cockpit lighting and instrument lighting
* Cabin general lighting
* Cargo bay lighting

• Instrument lighting is to ensure that the cockpit instruments are readable during all ambient lighting conditions.

• Ambient lighting- made up of three ceiling lighting strips located on each side of the overhead panel
• Storm lighting - provides maximum lighting in the cockpit to ensure that instrument panel light and ambient light are at their maximum brightness.
• Cockpit warning and Indication Lights - to ensured that all warning and indication lights can be functionally checked for serviceability
• Master Caution Light - indicates a fault in a particular system

• Cabin lighting - supplies illumination to the whole cabin in order to give passenger a comfortable environment.

Cabin lighting comprises:
* the cabin general illumination
* the lavatory lighting
* the reading and work lights
* the stand-alone signs.

• Service Lights - to provide illumination for cargo loading and maintenance activities

Areas are usually illumated by these system:

• forward and aft cargo compartment
• main and nose landing gear bays
• air conditioning bay
• APU bay
• avionics compartment.