Automatic prevention of flap extension on ATR?!?!?
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Automatic prevention of flap extension on ATR?!?!?
From the Colgan Buffalo accident thread:
As the full report is not available from NTSB site, (and given the findings listed, some embarrasment to NTSB might have been avoided this way) I'd like to ask anyone who remembers ATR from times after the Roselawn if this system was really installed on ATRs. I'm pretty sure that there was not a trace of it when I started flying ATR42 in 2001.
Originally Posted by Mansfield
To this we can add a concept that I once termed "automated interference with basic airmanship". During the Roselawn investigation, we determined that the upset initiated when the flaps were retracted following the overspeed warning during the descent. The captain was heard on the CVR to say "I knew we'd do that" in reference to the overspeed warning.
We found the flap handle in the wreckage selected to flaps 15. Simple good airmanship told the crew to restore the configuration to where it was before the upset initiated. Unfortunately, ATR at that time had a system in place that prevented the flaps from extending when the airpeed was beyond the appropriate speed limit. Had this not been in place, there is a chance that a recovery might have been completed.
We found the flap handle in the wreckage selected to flaps 15. Simple good airmanship told the crew to restore the configuration to where it was before the upset initiated. Unfortunately, ATR at that time had a system in place that prevented the flaps from extending when the airpeed was beyond the appropriate speed limit. Had this not been in place, there is a chance that a recovery might have been completed.
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The full report is available at this URL:
http://www.ntsb.gov/publictn/1996/AAR9601.pdf
Volume 2, the BEA response, is at
http://www.ntsb.gov/publictn/1996/AAR9602.pdf
Beware of slow connections...both are pretty long.
The following reference in the NTSB report is on page 25:
http://www.ntsb.gov/publictn/1996/AAR9601.pdf
Volume 2, the BEA response, is at
http://www.ntsb.gov/publictn/1996/AAR9602.pdf
Beware of slow connections...both are pretty long.
The following reference in the NTSB report is on page 25:
The MFC also monitors the trailing edge flaps and sounds an alarm if the
airplane exceeds an airspeed of 185 knots with the flaps extended at the 15-degree position. If the flaps are in the retracted position, the MFC will inhibit flap extension above an indicated airspeed of 180 knots (KIAS). After this accident, ATR Service Bulletin (SB) ATR 72-27-1039, dated January 12, 1995, provided a means to remove the flap extension inhibit logic so that flightcrews could select flap extensions in emergencies above 180 KIAS.
airplane exceeds an airspeed of 185 knots with the flaps extended at the 15-degree position. If the flaps are in the retracted position, the MFC will inhibit flap extension above an indicated airspeed of 180 knots (KIAS). After this accident, ATR Service Bulletin (SB) ATR 72-27-1039, dated January 12, 1995, provided a means to remove the flap extension inhibit logic so that flightcrews could select flap extensions in emergencies above 180 KIAS.
