
I'm not a crash expert, but I've been thinking about the possible causes of this and would like to share them. This is a tragedy and I don't mean to disrespect or demean the cerw for anything they did or didn't do. I'll try not to speculate on that too much.
the NTSB is now saying that both engines stalled or failed at FL410, and the aircraft's 15th stage bleed system was worked on by mechanics after an aborted TO in Little Rock after the crew received a 14th stage bleed overheat warning.
I don't have a CRJ200 MEL in front of me, but I assume maint MEL'D the 14th stage bleed system, which provides bleed air to the cowl and wing anti-ice systems. I assume they rendered the 14th stage shut off valves (SOV) closed, possibly placarding the cockpit switches and physically safety wiring the SOV's closed. I propose that the cowl and wing anti-ice was inoperative per the MEL. This means the crew had to avoid icing conditions in flight and be dispatched safely on a route and altitude which would permit them to avoid icing conditions.
If they encountered icing condtions and were unable to use the cowl anti-ice, that would endanger the engines.
Additionally, another scenario is that the CRJ200 has a limitation that if you operate it above FL400 then one air conditioning unit (PACK) or cowl anti-ice must be selected on for each engine. If somehow one or both PACK's failed at FL410 the aircraft would be operating in violation of this limitation, especially because the cowl anti-ice would be inoperative. I don't know the exact reason for this limitation, I asked during training and the instructor didn't know. I guess it would have to do with the engine needing to get rid of excess air at that altitude to enable combustion to continue. I don't believe dispatch would have filed the flight at FL410 if they had read the MEL and been doing their homework.
The PACK's have fewer protections if operated in manual mode. With two pilots and no passengers at FL410, it would've been a cold one and the PACK's would need a high output duct supply temp to warm the cabin. According to my system class notes automatic pack shutdown occurs if the pack outlet temp exceed 93 - 103 degrees C while being operated in manual mode. The PACK's have a high temp shutdown protection in Automatic mode.
Additionally, if somehow the aircraft was operated with one PACK inoperative at FL410, that is another limitation violation. The maximum single PACK altitude is FL250. I assume this is for the capability of the aircraft to have satisfactory pressurization, my fear is it also has to do with the operating pressure of the PACK. My systems notes tell me that during dual pack operation the pressure delivered to the packs is regulated to 30 psi on the ground, 41 psi for single pack operations, and the pack will shutdown with a pressure of greater than 51 psi.
If they encountered icing this theory accounts for a dual engine loss, if they lost one pack it proposes why they lost one engine and is murkey on the second loss. I have no idea why they were not able to restart the engines.
I can't believe another crash happened in MO. Continued thoughts and prayers go out for those affected by the Corporate Airlines crash.