Sudden Loss of Power

[Greg Gemelli]

I'm sure each airline is has their own specific envelope (all being very conservative) but at SkyWest we define icing conditions as:

Taxi/Takeoff - Temp less than 10 deg C OAT (outside air temp) and visible moisture (cloud, rain, snow, mist, fog, etc) In these conditions we run our Cowl anti-ice (engines). At the point of entering an active runway for the purpose of takeoff we turn on the Wing anti ice.

In Flight - Temp between 10 deg C OAT and minus 40 deg C SAT... below -40C SAT (Saturated Air Temp) no ice will form due to the lack of moisture... its too dry. So within this temp window we will run the Cowl AI anytime we are in visible moisture or we get an ICE indication from the ice detectors. We will run the Wing AI anytime we are in Icing conditions and below 230KIAS or ANYTIME we have an ICE indication from the detection system regardless of speed.

Based on your scenario... it's possible that this was a simulation (sim-ism) to simulate engine icing.. If turning on the Cowl (Engine AI) helped thats pretty indicative of whats going on... However in reality if your EGT is -20 it's quit running... You've had a flame out, which could be caused by icing... the reduction of your engine N1/N2 is also indicative of a flame out. So did you have to restart your engines?

[Greg Gemelli]

It sounds like you handled the situation well. Flew the plane first and then worked out the issue. Nice work It could have been icing or turbulence or maybe a lapse in fuel flow. Glad you made it

The good news for you was that you did have a flame out and it didn't end up in a core lock (core lock is nasty and you'll never restart a core locked engine). Seeing that your engine N1 (rpm) dropped to 17% means that you still had rotation (the engine core is windmilling) this is good as it means you had a shot at restarting the engine. In this scenario you did the first thing you want to do and that is descend. The last thing you want is to get slow and stall. Next If your plane has them, most do, IMMEDIATELY turn on the IGNITION as this combined with fuel flow may be enough to restart the engine at higher altitude. The next thing is to get yourself turned toward the most suitable airport to land at...this way if you don't get the engines started again at least you may have a chance of getting to an airfield. Next I would start the APU so you have a source of electrical power for avionics, AC Hydraulic pumps and a source of bleed air for restarting the engines. With that taken care of you can begin to focus most of your attention on the relight of those engines.

[Norberto Rivera]

I have some questions on run time for the deicing system Greg. Is that something you would turn on once tha APU is running or after engine start? Does it depend on the aircraft? Is there any point at which you wouldn't want it on like on takeoff or final or does it just stay on gate to gate as long as the conditions call for it?

[Greg Gemelli]

I have some questions on run time for the deicing system Greg. Is that something you would turn on once tha APU is running or after engine start? Does it depend on the aircraft? Is there any point at which you wouldn't want it on like on takeoff or final or does it just stay on gate to gate as long as the conditions call for it?

You've opened a can of worms haha

First it is aircraft specific from the standpoint of system architecture but not from the standpoint of when you would use it. Not knowing the operational limitations of (AI) anti-ice systems of other aircraft I will answer your questions as best I can using the CRJ as a reference.

Lets assume it snowing and you are at the gate. APU is up. At this point there is no need to run the Anti-Ice for either the engines or the wings. Once you pushback and have started your engines you would begin using the Engine/Cowl Anti-Ice (as now, since they are running you don't want the potential for ice buildup). In real world ops we would then taxi to get deiced. We don't use Wing Anti Ice on the ground when taxiing (the leading edges of the wings can, in extreme circumstances, begin to smoke...they get hot). We turn on the wings just before take off as we enter the runway. They stay on until we are out of icing conditions (see my previous post where I explain our definition of icing conditions).

Regarding landing in icing conditions. The Anti Ice absolutely stays ON. No exceptions. With some aircraft, like the CRJ200 you can't run the Engine/Cowl AI and Wing AI while in a Landing configuration as this places too much demand on the engines (Engine Bleed Air is what provides the hot air for the AI system). So in the case of the CRJ200 you must start the APU when you need to run the AI during take off or landing. When in cruise flight you can run the AI off the Engine bleeds. The CRJ700/900s don't have this issue thankfully.

After landing, lets say its still snowing... As you exit and run your after landing checklist you turn off the wing AI and taxi in with the Engine AI on... Just prior to engine shut down you turn the engine AI off.

Clear as mud

[Norberto Rivera]

Interesting. Thanks for the lesson sir. It's definitely clear as South Georgia clay.