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landing gear retraction.
DN Electrically initiates normal landing gear extension.
Emergency
(Rotate handle 90°
clockwise and pull
to the detent)
Mechanically initiates emergency landing gear extension.
2.7.1.5 DOWNLOCK ORIDE Button. The DOWNLOCK ORIDE button, located on the lower left
main instrument panel outboard of the LDG GEAR handle, is used to override the downlock solenoid.
If the downlock solenoid does not retract with WoffW (LDG GEAR handle cannot be moved from the
DN position), a failure has occurred in the downlock circuitry (Landing Gear Control Unit). If the
landing gear indicate three down and locked, cycling the landing gear handle is not recommended, as
proper landing gear functioning is questionable. However, if dictated by an emergency situation,
pressing and holding the DOWNLOCK ORIDE button will retract the mechanical stop and allow the
LDG GEAR handle to be moved to the UP position.
The LDG GEAR handle must be in the full down position for the mechanical stop to properly engage
after landing (WonW).
If the DOWNLOCK ORIDE button is pressed or the mechanical stop is
not fully engaged, the LDG GEAR handle can be raised on the ground,
and the main landing gear will retract. The nose gear will not retract with
weight on the nose gear.
2.7.1.6 EMERG LDG GEAR Handle (F/A-18F). The EMERG LDG GEAR handle is located on the
lower left main instrument panel in the rear cockpit. Pulling the handle to the detent mechanically
initiates emergency landing gear extension.
2.7.1.7 Landing Gear Control Unit (LGCU). The LGCU monitors the position of the landing gear and
launch bar systems, provides cockpit indications of gear/launch bar position, and provides outputs to
various aircraft systems which are dependent on gear position (e.g., FCC A and B, the SMS, and the
SDC). The LGCU does not control landing gear extension and retraction.
The LGCU receives inputs from the LDG GEAR handle, the LAUNCH BAR switch, and the
following proximity switches: launch bar, landing gear uplocks, landing gear downlocks, planing links,
and WonW. The LGCU controls the red and green L BAR warning/advisory lights, the landing gear
position lights, the light in the gear handle, the landing gear warning tone, the downlock solenoid, and
all inputs to the FCCs and the SMS. The LGCU also performs a self-BIT and a functional check of all
proximity switches, providing MSP code input to the SDC.
A1-F18EA-NFM-000
I-2-44 ORIGINAL
2.7.1.8 Landing Gear Warning Light and Warning Tone. The landing gear warning light is a red light
located inside the LDG GEAR handle. The landing gear warning tone is a beeping tone heard in the
headset. The landing gear warning light and warning tone serve three purposes: to indicate a mismatch
between LDG GEAR handle position and actual gear position, to warn of a planing link failure, and to
provide a ²wheels warning.²
A steady warning light comes on whenever the landing gear is in transit and remains on until all
three gear are down and locked (LDG GEAR handle DN) or all gear doors are closed and locked (LDG
GEAR handle UP). If the landing gear is unsafe, the landing gear warning light remains on. The
warning tone is inhibited for 15 seconds to allow for normal landing gear extension and retraction. If
the warning light remains on for 15 seconds, the warning tone is annunciated to provide an aural
indication of unsafe landing gear position.
If a left or right planing link failure occurs with the landing gear down and locked (planing link
proximity switch not properly activated), the landing gear warning light will come on immediately
accompanied by the warning tone.
Lastly, when the LDG GEAR handle is UP, a flashing warning light accompanied by the warning
tone will be activated when airspeed is below 175 KCAS, altitude is less than 7,500 feet, and rate of
descent is greater than 250 fpm. This ²wheels warning² is provided as a cue to check the position of the
landing gear at flight conditions where the LDG GEAR handle should normally be DN. The wheels
warning is also activated if calibrated airspeed and/or barometric altitude data are lost. In this case, the
standby airspeed and/or altitude indicators should be referenced prior to silencing the warning tone.
2.7.1.8.1 WARN TONE SIL Button. The WARN TONE SIL button, located to the left of the LDG
GEAR handle, is used to silence the landing gear warning tone.
2.7.1.8.2 Landing Gear UNSAFE Light (F/A-18F). The landing gear UNSAFE light is a red light
located on the upper left main instrument panel in the rear cockpit. The light indicates a mismatch
between LDG GEAR handle position and actual gear position (e.g., gear in transit). The light does not
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NATOPS Flight Manual 飞行手册 1(51)
