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Старожил
В этом документе: https://www.faa.gov/foia/electronic_reading_room/boeing_reading_room/media/737_AD_2019-NM-035fr.pdf
FAA комментирует предложения, озвученные видимо на открытом обсуждении, и разъясняет каким образом реализованы илине реализованы эти предложения в новом дизайне MCAS. Там есть практически все вопросы по MCAS, которые так или иначе всплывали с момента катастроф, включая предложение отказаться от MCAS вообще.
Там есть про тумблер AUTO OFF отключающий управление стабилизатором по каналу автопилота, который был в NG и который убрали, пишут так:
2. Comments Regarding Function of Aisle Stand Cutout Switches
Comment summary: Numerous commenters suggested changing the design of the aisle stand stabilizer trim cutout switches to resemble the design on pre-MAX versions of Model 737 airplanes. On those earlier Model 737 airplanes, two guarded switches on the aft end of the center aisle stand, aft of the throttle levers, are used to stop electric commands to the stabilizer trim motor. The pilots are directed to use the switches by two NNCs: Runaway Stabilizer and Stabilizer Trim Inoperative. In both procedures, the pilot
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is directed to “place both STAB TRIM cutout switches to CUTOUT.” On the earlier models of the Boeing Model 737, the switches have distinct functions (labeled “main” and “auto”) where one (auto) would cut out all FCC-generated stabilizer commands (autopilot and speed trim) and the other (main) would cut out pilot-generated commands (from the pilot thumb switches). On the 737 MAX, however, the switches are wired in series, and both perform the same function (primary and backup): to cut out all electric commands to the stabilizer (both FCC-generated commands and pilot commands). The commenters asserted that the configuration of the earlier (pre-MAX) Boeing Model 737 airplanes would allow the pilot to disable MCAS commands while retaining the ability to make electric trim inputs using the thumb switches. The commenters expressed concern that pilots would be required to use manual trim for the remainder of that flight.
FAA response: No change to the design or this AD is necessary to address the commenters’ concerns. The new MCAS has redundancy (receives inputs from two AOA sensors and is implemented by two FCC computers) and will automatically disable MCAS for the remainder of the flight if certain failures are detected. For detected failures where MCAS stops making commands, the pilot does not use the aisle stand cutout switches, and retains the ability to use thumb switches to control the stabilizer. The only time the thumb switches would be unavailable is if the pilot moves the aisle stand cutout switches to the cutout position; in that event, the pilot has the option to use manual trim to move the stabilizer. As discussed in the next paragraph, manual trim forces have been assessed and deemed acceptable.
Comment summary: Numerous commenters suggested changing the design of the aisle stand stabilizer trim cutout switches to resemble the design on pre-MAX versions of Model 737 airplanes. On those earlier Model 737 airplanes, two guarded switches on the aft end of the center aisle stand, aft of the throttle levers, are used to stop electric commands to the stabilizer trim motor. The pilots are directed to use the switches by two NNCs: Runaway Stabilizer and Stabilizer Trim Inoperative. In both procedures, the pilot
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is directed to “place both STAB TRIM cutout switches to CUTOUT.” On the earlier models of the Boeing Model 737, the switches have distinct functions (labeled “main” and “auto”) where one (auto) would cut out all FCC-generated stabilizer commands (autopilot and speed trim) and the other (main) would cut out pilot-generated commands (from the pilot thumb switches). On the 737 MAX, however, the switches are wired in series, and both perform the same function (primary and backup): to cut out all electric commands to the stabilizer (both FCC-generated commands and pilot commands). The commenters asserted that the configuration of the earlier (pre-MAX) Boeing Model 737 airplanes would allow the pilot to disable MCAS commands while retaining the ability to make electric trim inputs using the thumb switches. The commenters expressed concern that pilots would be required to use manual trim for the remainder of that flight.
FAA response: No change to the design or this AD is necessary to address the commenters’ concerns. The new MCAS has redundancy (receives inputs from two AOA sensors and is implemented by two FCC computers) and will automatically disable MCAS for the remainder of the flight if certain failures are detected. For detected failures where MCAS stops making commands, the pilot does not use the aisle stand cutout switches, and retains the ability to use thumb switches to control the stabilizer. The only time the thumb switches would be unavailable is if the pilot moves the aisle stand cutout switches to the cutout position; in that event, the pilot has the option to use manual trim to move the stabilizer. As discussed in the next paragraph, manual trim forces have been assessed and deemed acceptable.
Смущает, что как написано, защита при расхождении входных параметров отключает STS целиком? (вместе с MCAS) до конца полета с соответствующей индикацией, что хоть и является неким аналогом ALTERNATE LAW Airbus, но требует от пилотов активней работать триммером а главное держать в памяти что STS не подрулит, и это (введение законов управления в ручной самолет) непривычно для 737 и потребует навыка.
The new flight control laws now require inputs from both AOA sensors in order to activate MCAS. They also compare the inputs from the two sensors, and if those inputs differ significantly (greater than 5.5 degrees for a specified period of time), will disable the Speed Trim System (STS), which includes MCAS, for the remainder of the flight and provide a corresponding indication of that deactivation on the flight deck. The new flight control laws now permit only one activation of MCAS per sensed high-AOA event, and limit the magnitude of any MCAS command to move the horizontal stabilizer such that the resulting position of the stabilizer will preserve the flightcrew’s ability to control the airplane’s pitch by using only the control column. This means the pilot will have sufficient control authority without the need to make electric or manual stabilizer trim inputs. The new flight control laws also include FCC integrity monitoring of each FCC’s performance and cross-FCC monitoring, which detects and stops erroneous FCC-generated stabilizer trim commands (including MCAS).
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