retract the flaps.
Incorporated into the flap jackscrew actuators are force limiters that
prevent structural damage to the flaps from high airspeeds. If the flaps are
selected to a setting greater than that allowed by airspeed limits, the force
limiters will brake the motion of the jackscrews, preventing further
extension of the flaps (the jackscrews will continue to attempt to turn, but
are unable to overcome the force limiters). During the overspeed condition,
the flaps will operate in the opposite direction if retracted to a lower setting.
If the flaps are not retracted, the force limiters will release once airspeed
drops below the limit for the selected flap setting.
NOTE:
If airspeed exceeds the limit for the current flap
setting, the overspeed condition will be signalled by
the change in color of the airspeed tape on the PFD
and the OVERSPEED aural clacker will sound over
cockpit speakers.
D. FCU and Flap Operation:
The FCU uses RVDT data from the flap handle and flap position to drive
the PDU in the correct direction to extend or retract the flaps. The FCU also
uses flap handle RVDT data to position the horizontal stabilizer in the
correct position according to the schedule corresponding to flap position.
The FCU processor software also monitors performance of the flaps,
horizontal stabilizer and flap / stabilizer scheduled positions. If a fault is
detected, the operation of the malfunctioning unit (flaps or stabilizer) is
interrupted and through ARINC-429 connections to the MAUs, the MWS
generates the display of the appropriate CAS message(s). For instance, if
the FCU detects an asymmetry during the extension of the two wing flaps,
the FCU stops operation of the PDU and signals the condition to the MWS
through the MAUs. The MWS generates an amber “Flap Asymmetry”
caution message on the CAS display. (The complete list of CAS messages
pertaining to flap and horizontal stabilizer operation are shown at the end of
this section.)
Flap RVDT reported position is supplied by the FCU to open or close a
relay at a flap setting of twenty-two degrees (22°). The relay provides the
flap position input for the configuration warning horn of the landing gear
control system. The landing gear warning horn will sound if:
• Power levers at idle, flaps extended less than 22°, landing gear not
down and altitude less than three hundred fifty feet (350 ft.)
• Power levers at any setting, flaps extended more than 22° and
landing gear not down
The FCU is used to perform maintenance functions involving recalibration
of wing flap position to flap handle position and horizontal stabilizer position
to flap position. The maintenance process uses selector switches on the
face of the FCU to perform the recalibration. Various CAS messages will be
displayed during the maintenance procedure, and are included in the list at
the end of this section for information only.
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS2A-27-00
Page 50
August 14/03
To Next Page
Loading...
