Automatic prevention of flap extension on ATR?!?!?
From the Colgan Buffalo accident thread:
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. |
I used to fly ATRs 1996-2001 and they didn't have that kind of protection.
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It was on the ATR 72 not 42
The multi function computer MFC Checked speed before sending signal to activate flap |
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: 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. |
Thank you gentlemen for clearing up the facts for me.
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