The Airbus A330’s Trent 700 engine controls power and thrust as well as all the sub systems on the engine, this is centered around the Full Authority Digital Engine Control (FADEC) system.
The Power Control Unit (PCU), a dual-channel unit, plays a crucial role in managing the engine’s electronic control. It rectifies, filters, and regulates the power supply to the Electronic Engine Control (EEC) unit. This regulation is essential for various components such as the P20/T20 probe heater (which senses pressure and temperature of the air coming into the engine), the high-energy ignition circuits, and the cabin air bleed High-Pressure Valve (HPV) that is used to supply air to the aircraft systems.
The primary power source for the FADEC system is provided by a dedicated alternator, supplemented by a secondary backup from two aircraft 115V supplies. This backup is crucial during engine start-up, system failure, or ground testing. The PCU also has a distinct feature: its outer cover is coated with high emissivity paint for better heat dissipation, complemented by external fins to aid in cooling through convection and radiation.
The EEC, the heart of the FADEC system, is located on the fan case and shielded for protection against electromagnetic interference. It is a dual-channel digital unit, with each channel utilizing a high integrity computer concept for fault tolerance and efficient operation. The EEC automatically manages various engine functions such as engine starting, fuel flow control, bleed valve operations, and even emergency situations like engine shutdown during overspeed. It continuously monitors and adjusts engine performance based on various inputs, ensuring operation under varying conditions.
The engine’s operational safety is also checked by the Overspeed Protection Unit (OPU). This independent system is designed to prevent low and intermediate pressure shaft overspeed, which could result from malfunctions in the Variable Stator Vanes (VSVs) or fuel metering valve. The OPU works in tandem with the EEC, selecting satisfactory compressor speed signals and providing overspeed protection independent of the EEC, thereby adding a layer of redundancy to the engine’s safety mechanisms.
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