CRJ 100/200 wing inspection update in cold weather

[Foxtrot]

The uncommanded rolls during takeoff-is that a pitch angle issue?

Source: http://www.flightglobal.com/articles/2008/04/16/223012/additional-control-problems-spur-immediate-crj-directive.html

[P3_Super_Bee]

The uncommanded rolls during takeoff-is that a pitch angle issue?


No.

An aircraft rotates about three axis:

Longitutenal: Ailierons (Roll)
Lateral: Elevators (Pitch)
Yaw: Rudder

[Dmmoore]

The uncommanded rolls during takeoff-is that a pitch angle issue?

Source: http://www.flightglobal.com/articles/2008/04/16/223012/additional-control-problems-spur-immediate-crj-directive.html

If the pitch angle necessary to rotate the aircraft off the runway were less (read, higher airspeed) it's possible at the lower Alpha and higher airspeed, the drag increase and lift decrement from frost on the wings may be overcome and normal control could be maintained. Basically, the aircraft takes off in ground effect but the uneven clutter on the wings prevents normally expected lift being generated and one wing stalls. Even if 50% additional the aileron and rudder control were available, I doubt that a roll could be prevented.

[Foxtrot]

If the pitch angle necessary to rotate the aircraft off the runway were less (read, higher airspeed) it's possible at the lower Alpha and higher airspeed, the drag increase and lift decrement from frost on the wings may be overcome and normal control could be maintained. Basically, the aircraft takes off in ground effect but the uneven clutter on the wings prevents normally expected lift being generated and one wing stalls. Even if 50% additional the aileron and rudder control were available, I doubt that a roll could be prevented.

Ahh, I see. Thanks for that explanation.

[Airbus_A320]

US and Canadian safety authorities have issued an urgent update on how pilots should inspect the wings of Bombardier CRJ100 (http://www.flightglobal.com/directory/detail.aspx?aircraftcategory=commercialaircraft&manufacturertype=commercialaircraft&navigationitemid=389&aircraftid=318&manufacturer=3100&keyword=bombardier&searchmode=keyword)and CRJ200 regional (http://www.flightglobal.com/directory/detail.aspx?aircraftcategory=commercialaircraft&manufacturertype=commercialaircraft&navigationitemid=389&aircraftid=2468&manufacturer=3100&keyword=bombardier&searchmode=keyword) jets in cold weather
Urgent and just in time for summer!

On a serious note however, how many incidents have happened because of this? I know of the one in Germany with a challenger and one someplace Eastern Europe with a CRJ-200 both which resulted in crashes.

[speedlever]

IIRC from my CRJ school about 8 years ago, up to 1/8 inch of frost on the bottom of the wing was acceptable (due to condensation freezing after landing).

Has this changed? (or am I not remembering correctly?)

[Dmmoore]

The lower wing surface is less critical. The upper surface must be clean.

[speedlever]

Agreed, Don. Just curious if they had changed that too.