Gulfstream IV - Flap Control Circuit Breakers; Flap Operational Description

J. Flap Control Circuit Breakers:
The FLAP CONT circuit breaker incorporates a switch which closes if the
breaker opens (manually pulled or popped). Power through the closed
MANUAL FLAP CONT circuit breaker and asymmetry switches will then
energize the flap control relay. The flap control relay, in turn, energizes the
flap shutoff valve open and hydraulic pressure flows to the flap selector
valve. In this configuration, the EMER FLAP handle can be used to select
flap position. If the MANUAL FLAP CONT circuit breaker opens (manually
pulled or popped), both normal and emergency operation of the flaps is
inhibited.
K. Flap Operational Description:
(1) Normal Operation:
Moving the FLAP handle from one detent to another actuates one of
the four handle switches associated with the selected flap position.
The switch closes and power is routed through a follow-up switch
associated with the desired flap position and direction (e.g., down to
10°)totheflap control relay through flap asymmetry switches.
If the flaps are symmetrical, the flap control relay energizes. The flap
shutoff relay energizes to the open position and the flap selector
valve shifts to the extend or retract position. Combined, Utility or
Auxiliary hydraulic system pressure then flows through the open
shutoff valve to the selector valve, which directs pressure through
flow regulators to the appropriate side of the hydraulic motor.
As the hydraulic motor turns, it drives the flaps in the desired
direction through the central gearbox, torque shafts and screwjacks.
The central gearbox at the same time also drives the horizontal
stabilizer to the desired setting to maintain longitudinal stability.
When the flaps reach the desired position, the follow-up switch
opens, breaking the circuit to the flap control relay. The relay
de-energizes to close the flap shutoff valve and the flap selector
valve is de-energized closed. Hydraulic pressure stops and the flaps
stop moving.
(2) Emergency Operation:
Placing the EMERG FLAP switch to EMERG deactivates the normal
FLAP handle and follow-up switches to allow direct control of the
flap control relay. A red X appears on both the pilot’s and copilot’s
normalized AOA display (lower left portion of the Primary Flight
Display [PFD]). The flap control relay energizes to open the flap
shutoff valve and hydraulic pressure flows to the flap selector valve.
Flap asymmetry protection is still provided because flap control
relay power is routed through the asymmetry switches.
Moving the EMER FLAP handle from NEUTRAL to the FLAPS UP
or FLAPS DOWN position directs hydraulic pressure through the
flap selector valve to the hydraulic motor. The motor operates and
the flaps move. When the flaps reach the desired position, moving
the EMER FLAP handle to NEUTRAL stops the flaps.
3. Controls and Indications:
(See Figure 17.)
OPERATING MANUAL
PRODUCTION AIRCRAFT SYSTEMS 2A-27-00
Page 59
January 31/02
Revision 6