See and be seen
New LED systems bring greater reliability
On the outside, aircraft are equipped with an array of different lights. Variations in the color, position and function of these light sources make it possible to distinguish, amongst other things, between the starboard (green = right) and port (red = left) sides of the aircraft from some distance away. The collision warning lights on an aircraft are attached at the extremities such as the wingtips and the tail section (white = behind) and also above and below the fuselage (red flashing lights). In this way it is possible not only to spot every aircraft from any angle but also, on the basis of the light color, to ascertain the direction in which the aircraft is currently traveling. Again, other lamps such as the landing and taxi lights promote safety on the ground or else, in the case of logo lights, serve promotional purposes.
The lights on the outside of an aircraft are essentially safety lights and most of the requirements apply to the situation where an aircraft is flying in the dark. However, some of them also fall under the visual flight rules (VFR) requirements that apply to daytime flying. The collision avoidance position lights have to be operated day and night. To improve reliability still further, the light output and service life of the lights was increased through the use of light-emitting diode (LED) technology. Together with its partners, Röder Präzision, Honeywell, Teledyne and Goodrich Lighting Systems GmbH, Lufthansa Technik is offering a new generation of LED lights for the exterior lights of commercial aircraft. These are already in use on the Boeing 747 and the Airbus A320 family and will later be available for the Airbus A330/A340 fleets as well.
The new LEDs – it is not just a matter of new light elements but newly developed, complete systems – offer many advantages over the bulbs used up to now: whereas halogen lamps have a life expectancy of just 50 to 2,000 hours, the LED lights, being a cold light source – unlike bulbs, which radiate heat – have a working life of over 30,000 hours. They are also resilient to knocks and vibration, resulting in substantial savings on not just the material costs but especially on the associated maintenance costs. To achieve a high life expectancy on the exterior of aircraft it was necessary above all to optimize the thermal management, as operating temperatures greater than 80°C drastically reduce LED service life.
The new LEDs are a lot more economic, yet they are also much brighter due to the higher light spectrum. The A320 LED runway turnoff light (RTO) and logo light produced by Goodrich Lighting Systems GmbH illustrate the high energy savings that are possible. Whereas in the past 150 W halogen lamps were used, the LEDs are not only brighter but require just 35 W in the case of the logo light and 55 W in the case of the RTO. Both systems have an EASA Supplemental Type Certificate (STC) and can be installed on customer aircraft with older systems without any modifications. The wingtip navigation light produced by Honeywell is more than three times as energy-efficient, requiring just 15 W instead of 50 W.
On the basis of these advantages Airbus has decided to fit all A320 family aircraft with exterior lights using the new LED technology by the second quarter of 2014. Certification of the LED logo light for the Airbus A330/A340 fleet is expected later this year. All remaining aircraft in Lufthansa´s Boeing 747-400 fleet are already equipped with LED logo lights, and the navigation lights are expected to be certified shortly. The taxi and turnoff lights were certified at the beginning of 2013.
For customers, the new LED technology is becoming more and more important, not just for exterior lighting but also for cabin lighting. Significant savings on energy and maintenance costs coupled with greater safety and improved visibility will considerably enhance their image. In this sense, "See and be seen" is more important today than ever before in the area of exterior lighting.