BAe 146/AVRO RJ Cold Start

One of the positive features of Bae 146 and AVRO RJ aircraft is their versatility and ability to operate in rough and extreme environmental conditions. They can take off and land with steep angles, in unpaved runways, and they can start their engines can be started using 28V DC electric power when there are no AC Auxiliary power sources. All these are positive features that make these aircraft unique compared to their latest and modern counterparts. One feature I am going to discuss in this article is Cold Start. Via Cold Start system, BAe 146 and AVRO RJ engine electrics starters will be supplied with 36V DC instead of normal 28V DC. This excessive electrical voltage will boost the performance of the electric starter and will allow the engine to light up faster which would be a plus after hung or hot starts to reduce the imposed thermal and electrical loads on engine components by curbing the engine light-up period, thus improving the possibility of the engine to start successfully after one or more unsuccessful consecutive engine starts. However, Cold Start imposes high electrical loads on aircraft electrical components specially Transformer Rectifier Units and external AC power supplies which necessitates the external power units to be able to supply at least 90 KVA power and avoiding the use of Cold Start for normal conditions. Apart from the technical advantages of such a system, Cold Start can reduce flight delays. Lycoming ALF 502 engine starter duty cycle in normal conditions mandates a one-hour engine cooling time for each 3 consecutive unsuccessful start attempts. Cold Start can ensure a successful engine start by boosting the starter performance and avoid further time-consuming cooling time procedures which would usually lead to reduced flight delays and resulting customer satisfaction. Therefore I believe this feature has made these aircraft more robust, self-reliant, and operable in abnormal and severe environmental conditions.