CRJ7/9 Flap Positions and Uses
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CRJ7/9 Flap Positions and Uses
Can one of the CRJ fliers out there clarify this for me:
What are the (typical) uses of the various flap positions on the CRJ7/9?
My understanding is that 8 is normal takeoff, 20 is short field takeoff, 30 is approach, and 45 is landing.
Is 1 used for anything except as a brief pause during acceleration?
Is any flap position typically used for holding or extended approach?
What is typical takeoff for the 9?
Is 30 ever used for landing?
And, you know, anything interesting that comes up in the discussion.
Cheers.
What are the (typical) uses of the various flap positions on the CRJ7/9?
My understanding is that 8 is normal takeoff, 20 is short field takeoff, 30 is approach, and 45 is landing.
Is 1 used for anything except as a brief pause during acceleration?
Is any flap position typically used for holding or extended approach?
What is typical takeoff for the 9?
Is 30 ever used for landing?
And, you know, anything interesting that comes up in the discussion.
Cheers.
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Only for a failure case. The only approved landing configuration is flaps 45. Anything else can occur only as a result of an abnormal or emergency procedure, and from memory the only ones of those which would end up as flaps 30 for landing are the flap fail cases.
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Only for a failure case. The only approved landing configuration is flaps 45. Anything else can occur only as a result of an abnormal or emergency procedure, and from memory the only ones of those which would end up as flaps 30 for landing are the flap fail cases.
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Single engine approach and landing is flaps 20.
As a general rule of thumb, on all the CRJ-family, if a failure case directs you to a flap selection other than 45, usually flaps 20 is the value.
As far as I know, the only case where you would land at flaps 30 is when the flaps will not move from that position i.e. the "flaps fail" and "slats and flaps fail" cases.
As a general rule of thumb, on all the CRJ-family, if a failure case directs you to a flap selection other than 45, usually flaps 20 is the value.
As far as I know, the only case where you would land at flaps 30 is when the flaps will not move from that position i.e. the "flaps fail" and "slats and flaps fail" cases.
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Thanks for the info, much appreciated.
One more CRJ question: does the Vmo/Mmo display on the airspeed tape respect the placard speeds during flap extension/retraction or is it just the absolute airframe limit? Same question to the low speed warning on the airspeed tape does it reflect aerodynamic reality (from stall warning system), rule-of-thumb minimum speed based on configuration, or is it static?
Thanks!
One more CRJ question: does the Vmo/Mmo display on the airspeed tape respect the placard speeds during flap extension/retraction or is it just the absolute airframe limit? Same question to the low speed warning on the airspeed tape does it reflect aerodynamic reality (from stall warning system), rule-of-thumb minimum speed based on configuration, or is it static?
Thanks!
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I believe that the checkerboard that indicates Vmo/Mmo on the speed tape with slats and flaps retracted drops down to represent the appropriate VFE speed when slats or flaps are extended. For certain the overspeed clacker resets; I can't 100% confirm that the display resets but I believe it does.
The low speed warnings - both the "Low Speed Awareness Indicator" (green line, FAA aircraft only) and the Low Speed Cue (checkerboard) are driven by Stall Protection System parameters and are adjusted based on the current "aerodynamic reality". They can't, however, adjust for things the SPS doesn't know about, so a contaminated wing (which will stall early) isn't catered for, nor are certain fairly obscure failure cases. For some other failure cases, they may be set to conservatively cover all possibilities (if the slat/flap control units all fail, the SPS won't know where the slats and flaps are, so will use a default, conservative, slat/flap position. (Where a failure case does invalidate the indications, the failure procedure should provide guidance)
The low speed warnings - both the "Low Speed Awareness Indicator" (green line, FAA aircraft only) and the Low Speed Cue (checkerboard) are driven by Stall Protection System parameters and are adjusted based on the current "aerodynamic reality". They can't, however, adjust for things the SPS doesn't know about, so a contaminated wing (which will stall early) isn't catered for, nor are certain fairly obscure failure cases. For some other failure cases, they may be set to conservatively cover all possibilities (if the slat/flap control units all fail, the SPS won't know where the slats and flaps are, so will use a default, conservative, slat/flap position. (Where a failure case does invalidate the indications, the failure procedure should provide guidance)
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just-nick,
Flaps 20 is used for take-off on contaminated runways as well. But, other than that, you are correct in that flaps 20 will be used for runway length considerations. "flaps 1" just moves the slats to their first extension location.
cheers--
Flaps 20 is used for take-off on contaminated runways as well. But, other than that, you are correct in that flaps 20 will be used for runway length considerations. "flaps 1" just moves the slats to their first extension location.
cheers--
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@just nick,
the barberpole (vmo limit) does indeed move with flap extension, just like the clacker indicates overspeed for current flapsetting.
The clacker only sounds when > 5 kts overspeed is achieved, thus beyond the first red bar on the pfd-barberpole.
During flap extension though, the clacker can be a little cranky and sound momentarily although no overspeed condition actually exists.
I loved flying the CRJ, have fun....
the barberpole (vmo limit) does indeed move with flap extension, just like the clacker indicates overspeed for current flapsetting.
The clacker only sounds when > 5 kts overspeed is achieved, thus beyond the first red bar on the pfd-barberpole.
During flap extension though, the clacker can be a little cranky and sound momentarily although no overspeed condition actually exists.
I loved flying the CRJ, have fun....
