Dash8 flight crew experiences uncontrollably hot pack output temperatures necessitating pack shut down and descent due to loss of pressurization. After completing the QRH procedures and coordinating the diversion; the First Officer notes that engine torque is over the limit and pulls the power levers back.
Synopsis
Dash8 flight crew experiences uncontrollably hot pack output temperatures necessitating pack shut down and descent due to loss of pressurization. After completing the QRH procedures and coordinating the diversion; the First Officer notes that engine torque is over the limit and pulls the power levers back.
Narrative
I was pilot flying. An emergency developed when the cabin duct temperature gauge went in to the red and Cabin Duct Hot and Flight Compartment Duct Hot caution messages displayed. We became very busy during this emergency. We ran our emergency checklists and worked with ATC to descend to 10;000 because it became necessary to shut the bleed air off as no other checklist methods worked to cool the rapidly rising cabin duct temperature. At some point after leveling at 14;000 FT the First Officer noted an over-torque condition on the torque meters. He immediately pulled back the power levers to within limitations. He notified me of the situation as he corrected it. My only explanation is that during the intense workload of handling many aspects of the emergency I allowed the torque setting to exceed limitations. Upon landing my First Officer and I promptly wrote up the over-torque condition as safety obviously dictated.Factors I feel that may have contributed to this mistake: Being new to the aircraft may have contributed: Although I am well trained; certainly proficient on the DASH 8; and will NEVER make this mistake again; I theorize that because the previous aircraft which I flew for nearly 7 years was fully FADEC equipped; my muscle memory may still desire to push the power levers to the detent; especially during high task saturation events. I was intently monitoring Cabin Pressure as my First Officer performed the following pilot not flying duties: he ran checklists; spoke with the Flight Attendant (she called repeatedly to inform us that the cabin was becoming excessively hot); attempted unsuccessfully to contact Dispatch; worked with ATC for lower altitude; declared the emergency; checked the weather at our alternate; briefed the passengers; among other things. During all of this it also became necessary to don our oxygen masks. We were extremely busy in the physical sense but were also heavily tasked mentally trying to make good decisions.
Second reporter narrative
During cruise the Flight Attendant called and asked for more heat; so I increased the heat and almost immediately the Cabin Duct Temp gauge went into the red. Cabin Duct Hot caution and Flight Compartment Hot caution messages on caution advisory panel displayed shortly after. As per our company procedures; I then referenced the QRH and ran the appropriate checklist; which called for us to descend to 14;000 FT as soon as possible and upon arrival to open the forward outflow valve amongst other things and go unpressurized. I then requested the lower altitude with Center and asked to divert. Soon after; upon instructions from the Captain; I declared an emergency because ATC only lowered us to 14;000; and getting to our requested altitude of 10;000 was not happening as quickly as desired. After declaring an emergency we were given 10;000 immediately and continued our diversion. While all this was happening; the Flight Attendant repeatedly called up front to inform me that the cabin was becoming increasingly hot. As I was just finishing up referencing the QRH to make sure that we had accomplished everything required by the manual; as well as referencing charts for our new route; I looked up at our altitude and airspeed and as my eyes came across the engine gauges I noticed that both the number 1 and 2 engines were over torqued. I immediately brought it to the Captain's attention and retarded the powers levers to an acceptable level. Upon landing we discussed the over-torque situation and decided the responsible thing to do would be to put safety first and write it up.It's hard to say what would be a proper way of avoiding this situation again; without changing company/industry standard procedures that have one pilot flying and one pilot reading and executing published checklist procedures. The only thing I can think of is not to change it but to strengthen the standardized procedure of splitting responsibilities. By this I mean we need to encourage the flying pilot to do just that 'FLY.' To not get caught up focusing on other responsibilities; allowing the non-flying pilot to do his/her job.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.