I'd imagine the design of the aircraft makes it real hard to visually check for ice unless it's real bad but there must ice lights at least. And in that situation(known ice conditions) I'd imagine SOP would be to activate de ice systems regardless if they thought they were icing up or not. Can anyone comment on that? Would they be required to run the boots by either checklist or company policy?
Our SOP mandates we run the boots every 3 min in known conditions in the pilatus but it's so easy to look for ice on the wings. Justnot the tail which could be a similar situation in this case.
The Q400 has posts on the wipers with lights to visually ID ice, as well as and electronic ice detection system that gives you an ED message of "
Ice Detected" which then turns white when ice protection is appropriate ( all on)
we have 4 levels of ice protection. 0 is all off (only when parked at the gate) and shut down. Level 1 is engine bypass doors open, both Mains and stby pitot heats on. Level 2 adds windscreen heat and prop blade deice. It also sets a minimum requirement of 65 deg C for the oil temp ( oil heats the engine inlet area) - bypass door heat is AC powered and automatic, no setting needed, and importantly, the "Increased Ref" switch is set to Increase, putting the Stall protection computers into "icing" mode (adding roughly 20kts to most areas of the stall protection envelope. Level 3 adds deice boots. Fast for climb, descent, or when slow isn't enough. slow can be used in cruise.
Level 1 is the minimum protection level anytime the aircraft is operating (ground/flight)
Level 2 is selected when : On Ground, IAT 10deg or less, visible moisture, runway contamination, visibility less that 3/4mi. Inflight - Temps 5deg or less, visible moisture.
Level 3 for whenever ice is detected either visualy on the representative surfaces or, by the ice detection system.
The boots operate in 6 different sections, alternating at the inboard section of the wing, also alternating the engine inlet boots to prevent a dual flame out in the case of ice ingestion when the boots inflate. The inflate cycle is 6 seconds per section, and is inflated to 17-20psi... A warning is received for less than 17 psi in 6 seconds. The recently inflated boot is then suctioned back to the wing surface with ejector pump suction. Each Section is controlled by a dual distribution heated valve, which allows ice protection with a bleed source leak, or an engine failed. Fast mode has a 36 second Active, followed by a 24 second dwell period, each boot section is deflated for 54 seconds during the deice process though. Slow adds a minute to the dwell time.
Deice air is provided by a full time, intermediary bleed, which is not connected to the High or low service bleeds, allowing ice protection with a bleed leak.
Both main pitot tubes are heated by AC power, and Both will operate with the loss of 1 ac gen. The Standby is DC powered and will operate with only 1 of 6 power sources operating.
The windscreen heat is also ac powered, the FO's side will load shed in the case of a TRU failure and DC gen Failure. The Captains side window is also heated with a separate switch. Normal mode heats to 90deg within 5 minutes, or a warning activates.
Stall speed is calculated by the SPM ( stall protection module) which take AOA, speed, flap, power, temp, altitude data, Increased ref switch, and calculates a stall speed. It also activates both the stall pusher, and shaker.
Stall Pusher depending on conditions may be less than .83Vso, and I believe that in certain conditions, the shaker itself may activate below Vso as well.
This is due the high level of airflow over the wings from the props at high power settings.
The Q400 has a elevator, one of the reasons for the .64Mmo . The engines are mounted 5(?) degrees nose low, to counter the effects of location relative to cg. it may be more or less than 5 deg, i forget. There is a slight pitch force change with power change, but not much.
The Trim on the Q only adjusts the "position" of the elevator actuators. If you hit the trim disconnect, it will resort to flying exactly where the control collum is. This also disengages elevator feel though... so it would be tricky, but you wouldn't have to fight the trim. I honestly have no idea where the trim would reset to if reengaged... maybe hitting the trim discon switch light as soon as you ran into a problem would buy you time to prep for it..
from design, and testing, bombardier claims that the Q400 tail is not supposed to have a tailplane stall. ymmv
). He was actually cool about it, though. We had just gotten approved for GPS approaches like a day earlier, and he'd been at the airline for a while, so he missed the whole GA GPS revolution. It was a "Hey, I've never flown a GPS approach. Would you mind walking me through it?" type thing. Honestly, I'd rather a CA (or FO) be honest than try to bluff their way through it acting like they know what's going on.
