From: firstname.lastname@example.org (Dave J.) Organization: NASA Langley Research Center, Hampton, VA USA Date: 17 Nov 93 15:34:35 PST References: 1
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>According to Flight International, 10 NOVEMBER 1993, "an automatic >engine-control function in the McDonnell Douglas MD-81, of which the >operating airline was unaware, was a major factor in the Scandinavian >Airlines System (SAS) accident near Stockholm, Sweden, in December 1991, >says the official report into the accident" >In summary, it seems that the airline failed to detect clear ice on the >wings before takeoff. The ice broke free and entered the engines damaging the >fan stages. This caused the right engine to surge. The pilots retarded the >right throttle. The automatic thrust-restoration system ATR caused both >throttles to advance without the pilots noticing, making the surging worse >in the right engine and starting surging in the left. The surges destroyed >the engines. >It seems that SAS were unaware of the ATR, which was documented but in a >section of the production flight-procedure manual dealing with noise >abatement. SAS VP Johan Juhlin is reported as saying "We did not order it. >It was hidden in the computer. The only way to disconnect the ATR was to >disconnect the whole autothrottle system." Could you be referring to the "ARTs" system - automatic reserve thrust? It will fire in the takeoff mode based on certain logic such as altitude rate, radar altitude and airspeed.