A rotation sensor is installed on each of the outer flap screw actuators. These sense the
rotation of the flexible shafts and give signals to the FCWU. The FCWU monitors these signals
for asymmetrical flexible shaft rotation of more than 20 rotations (caused by a broken inner flap
drive shaft). If failure is detected, the FCWU disconnects the power to the PDU and the CAS
window will show a Flaps caution. This condition cannot be reset by pilot action. To detect
satisfactory system operation, the FCWU monitors the left sensor for 10 rotations of the flexible
shaft in the first 7 seconds of a flap up or down selection. If the selected flap position is not
achieved the FCWU disconnects the power to the PDU and
Flaps
will be shown.
There are five position sensors in the flap system, one at each center flap actuating arm, one
at each inner flap actuating arm and one on the flap position lever, which give signals to the
FCWU. The FCWU monitors the signals from the left and right flap sensors for flap asymmetry
(caused by a broken inner flap drive shaft). If an asymmetry is detected, power to the PDU is
disconnected and
Flaps
will come on. Flap panel asymmetry occurs when the difference
between the left and right flap angle exceeds a specific angle in accordance with the table
below.
Table 7-3-1: Flap Position Symmetry Limits
Flap position between:
Asymmetry occurs when the left and right
flap panel difference is at least:
0° and 15°
1.6°
15° and 30°
4.3°
30° and 40°
5°
The FCWU also monitors the signals from the left and right flap sensors for twisting of the left
or right flap (caused by a broken outer flap drive shaft or unequal movement of the flap screw
actuators). If a failure is detected, the FCWU disconnects the power to the PDU and the CAS
window will show a Flaps caution.
Additionally if flap asymmetry or twist is detected and the flap angle is greater than 2° after 10
seconds, the
Pusher
will show and the stick pusher will default to ‘safe’ mode.
Pusher
Safe Mode
will show in the CAS window. In the ‘safe’ mode the stick pusher will operate at
the flap 0° flap speed setting.
If the PDU motor overheats or a stalled motor condition is detected, a signal from the PDU will
open the FLAP circuit breaker on the Generator 1 Bus circuit breaker panel. The FCWU then
removes the up or down command to the PDU and the CAS window will show
Flaps
. After
waiting for a period of 5 minutes the FLAP circuit breaker can be reset (max. 2 attempts) and
normal flap operation resumes. This is the only pilot resettable failure and cycling the flap
circuit breaker, if it has not opened, will not reset any other failure mode detected.
To avoid an inadvertent flap down command at high speed, flap down enable is disabled when
the flap selector handle is in the 0° position.
Flap system operation may be stopped at any time by lifting the switch guard and pressing the
INTERRUPT FLAP switch on the center console to INTR. The CAS window will show
Flaps
.
If the switch is moved back to the NORM position, normal operation will not resume, even if the
FCWU does not detect any failures.
A FLAP GROUND RESET switch is installed on the maintenance test panel (right sidewall
behind the copilot seat). The FLAP GROUND RESET switch is only operational on the ground
for maintenance purposes.
Section 7 - Airplane and Systems Description
Flaps
Pilot's Operating Handbook
Report No: 02406
Issue date: Mar 06, 2020
Page 7-3-3
12-C-A15-00-0703-00A-043A-A
FOR
GENERAL
AND
FAMILIARIZATION
PURPOSES
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