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Systems Trivia: H60T Environmental Control System (ECS) 

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  1. Q: Flow switch?  
    A: Norm, high. 
     
  1. Q: Temperature control knob? 
    A: Only used in auto only. 
     
  1. Q: Hot/cold toggle switch? 
    A: Used in manual mode to adjust temp (usually if auto mode failed). 
     
  1. Q: EICAS display advisory? 
    A: ECS SHUTDOWN, ECS HI PRESS. 
     
  1. Q: ECS shutdown? 
    A: ECS always shuts down during start, when contingency power is turned on with the C power switch or when an ECS duct overtemp is sensed (there will be no ECS shutdown advisory for start or underpressure). When air source is in engine, ECS will shutdown when engine anti-ice is turned on (auto or manual), when TGT reaches 851 (the number on EICAS) and when an underpressure exists. 
     
  1. Q: ECS HI PRESS? 
    A: ECS continues to operate. The system can handle bleed air from the engines and the APU. This advisory indicates a fault in the modulating valve and should be noted. ECS can continue to operate. 
     
  1. Q: ECS operation? 
    A: Bleed air passes through a modulating valve. Next it goes through a venturi which limits the max flow rate through the system. After the venturi the bleed air splits. One path leads directly to the cabin temperature control valve to provide hot air if necessary. The other path goes through two heat exchangers (simply radiators that provide air to air cooling). The bleed air also drives a air cycle machine and a fan. The air cycle machine (ACM) compresses the air and the fan blows the hot air away from the air to air coolers and out the ECS exhaust (cooling air enters and exits the right side of aircraft).  Rapid expansion of the bleed air exiting the compressor (turbine) cools it. Water vapor that was removed during the compression exits at the water separator. This cool air is mixed as necessary with the hot bleed air at the cabin temperature valve and sent to the cabin, cockpit and avionics as necessary.