GM2 ADR.OPS.C.015(b) Maintenance of visual aids and electrical systems

LED LIGHTS — MAINTENANCE PROGRAMME — ICING AND SNOWING CONDITIONS

(a) The energy savings of light emitting diodes (LEDs) are due in large part to the fact that they do not produce the infrared heat signature of incandescent lamps.

Thus, operators of aerodromes with presence of ice or snow, who have come to expect their melting by this heat signature, need to evaluate whether or not a modified maintenance schedule is required during such conditions, or evaluate the possible operational value of installing LED fixtures with heating elements. Manufacturers can provide a heater, sometimes referred to as an ‘arctic kit’, for their LED light units. Whether a heater is needed is dependent upon the site location and the weather conditions to which it is exposed. In some instances, the low-operating temperature is an advantage in that drifting snow does not melt and attach itself to the fixture lens. It is likely that LED PAPI will require some form of lens heater regardless of site location to ensure that condensation/icing does not occur.

(b) While LEDs could last for many thousands of hours under certain conditions, the life of the LED itself, and more importantly, that of the complete luminaire including the electronics, still depends on the system integration and the actual conditions in which the luminaire is used. Application conditions that could have an impact on the expected life of the luminaire include, primarily, the temperature of operation, on-off cycling patterns and humidity. Because LEDs do not have filaments that break or deteriorate, when operated under normal conditions, they tend to last for a long time. However, their light output decreases and the colour of their light shifts over time, with the rate of depreciation increasing at higher-operating temperatures. The implication for practice is that at some point in time the loss of light output or the colour shift may render the LED source outside the specifications for a given application or purpose; while the LEDs may technically still be operating, they would no longer be considered useful.

Therefore, the long life of the LED in comparison to that of an incandescent lamp may not be taken as a reason for ‘install and forget’. A system of preventive maintenance is necessary as the LED light does eventually fail. In addition, there are other factors that can reduce performance, such as contamination on the lens of in-pavement fixtures.