Beechcraft C-12C Operator And Technical Reference Manual page 35

e. Landing Gear Warning System
landing gear warning system is provided to warn the
pilot that the landing gear is not down and locked
during specific flight regimes. Various warning modes
result, depending upon the position of the flaps. With
the flaps in the UP or APPROACH position, refer to
Figure 2-9, Sheet 1, and either or both power levers
retarded below approximately 79% N
horn will sound intermittently and the landing gear
switch handle lights will illuminate. The horn can be
silenced by pressing the WARNING HORN SILENCE
switch adjacent to the landing gear switch handle; the
light in the landing gear switch handle cannot be
canceled. The landing gear warning system will be
rearmed if the power lever(s) are advanced. Retarding
the second power lever below 79% N
landing gear horn even though the silence system has
been activated.
To prevent the warning horn sounding during
long descents or an ILS approach, a pressure
differential "Q" switch is connected into the copilot's
static line. This switch prevents the warning horn from
sounding until airspeed drops below 140 KIAS.
With the flaps beyond the APPROACH position,
the warning horn and landing gear switch handle lights
will be activated regardless of the power setting. The
horn cannot be silenced in this case.
T The landing gear warning system is provided
to warn the pilot that the landing gear is not down and
locked during specific flight regimes. Various warning
modes result depending upon the position of the flaps.
At airspeeds above 140 KIAS with flaps in up or
APPROACH position and either or both power levers
retarded below approximately 79% N
horn, located in the overhead control panel, will sound
and the landing gear switch handle lights will
illuminate. The horn is automatically silenced by a "Q"
switch; however, the gear switch handle lights cannot
be extinguished. The pressure differential "Q" switch
is connected into the static line. This switch prevents
the warning horn from sounding steadily until airspeed
drops below 140 KIAS.
At airspeeds below 140 KIAS with flaps in the up
or APPROACH position with either or both power
levers retarded below approximately 79% N
warning horn will sound and the landing gear switch
handle lights will illuminate. The horn can be silenced
by actuating the WARNING HORN SILENCE switch,
located adjacent to the landing gear switch handle to
the up position. However, the lights in the landing
gear switch handle cannot be canceled.
warning silence switch is a magnetically held switch.
Once actuated, it will stay in the up position until both
D2 . The power levers are advanced above 81% N
airspeed increases above 140 KIAS.
140 KIAS), the landing gear warning system will be
rearmed if both power levers are advanced above 81%
N
1
, the warning
1
the warning horn and landing gear switch handle lights
will be activated regardless of the power setting. The
horn cannot be silenced in this case until either the
landing gear is lowered, or the flaps are retracted to
the up or APPROACH position and the WARNING
HORN SILENCE switch is actuated to the up position.
will activate the
1
The warning horn and gear handle lights can be tested
by placing the switch, placarded STALL WARN TEST
/ OFF / LDG GEAR WARN TEST, to the LDG GEAR
WARN TEST position.
illuminate and warning horn will sound. Releasing the
LDG GEAR WARN TEST switch to the OFF position
will extinguish the gear handle lights and silence the
warning horn. The landing gear warning horn circuit is
protected by 5-ampere circuit breaker, placarded
LANDING GEAR WARN, located on the overhead
circuit breaker panel.
switch on each main landing gear shock strut controls
the operation of various aircraft systems that function
only during flight or only during ground operation.
These switches are mechanically actuated whenever
the main landing gear shock struts are extended
(normally after takeoff) or compressed (normally after
landing). The safety switch on the right main landing
, the warning gear strut deactivates the landing gear control circuits,
1
cabin pressurization circuits, and the flight hour meter
when the strut is compressed.
activates a down-lock hook, preventing the landing
gear from being raised while the aircraft is on the
ground. The hook, which unlocks automatically after
takeoff, can be manually overridden by pressing down
on the red button, placarded DN LOCK REL, located
adjacent to the landing gear handle. If the over-ride is
used, the landing gear warning horn will sound
intermittently and two red, parallel-wired indicator
lights, located in the landing gear control switch
handle, will illuminate, provided the battery switch is
the
1
on. The safety switch on the left main landing gear
strut activates the left and right engine ambient air
shut-off valves when the strut is extended.
The gear extension
ALTERNATE EXTENSION, is located on the floor
between the crew seats. The pump is located under
In either case (speeds
.
With the flaps beyond the APPROACH position,
f. Landing Gear Warning Horn Test Switch.
g. Landing Gear Safety Switches.
h. Landing Gear Alternate Extension.
lever, placarded
TM 1-1510-218-10
and/or
1
above or below
The gear handle lights will
A safety
This switch also
LANDING GEAR
An
2-19