MN-FLT-OH-201
B-18 Page 19 of 22
Flight Crew Operations Manual Bulletin No. GOT-18 , Dated March 1, 2021 (continued)
Flight Control Computer Monitors
The Flight Control Computers contain monitors which provide protection against
possible runaway stabilizer conditions caused by erroneous FCC stabilizer trim
commands. The FCCs continuously monitor each other’s stabilizer trim
commands, and in the event an erroneous command is detected, stabilizer trim
commands, autopilot trim commands, and CWS trim commands are stopped and
inhibited for the remainder of the flight for that FCC. These trim commands are
then provided by the other FCC. In addition, main electric stabilizer trim remains
available.
Autopilot Elevator Monitor
The Autopilot Elevator Monitor protects against erroneous elevator commands
that can result in erroneous autopilot stabilizer trim commands. The Autopilot
Elevator Monitor is available when:
• Autopilot is engaged, in single channel, and
• Pitch mode is other than G/S or G/P, and
• Flaps are 15 or less.
If the Autopilot Elevator Monitor activates:
• The STAB OUT OF TRIM light illuminates in flight and remains
illuminated until the condition is no longer present or the autopilot is
disengaged.
• The STAB OUT OF TRIM light illuminates after landing when
groundspeed is less than 30 knots.
Note:
The Speed Trim System remains available.
Stabilizer Cross-FCC Trim Monitor
The Cross-FCC Trim Monitor protects against erroneous stabilizer trim
commands. The Cross-FCC Trim Monitor is available when a single autopilot is
engaged and during manual flight.
If the Cross-FCC Trim Monitor activates:
• The autopilot or CWS can automatically disengage causing the associated
aural and visual alerts.
• The SPEED TRIM FAIL light can illuminate automatically, during
MASTER CAUTION recall, or not at all.
• The STAB OUT OF TRIM light illuminates after landing when
groundspeed is less than 30 knots.
March 1, 2021
