Airplane Description DA 42 AFM
Page 7 - 14 Rev. 8 15-Dec-2017 Doc. No. 7.01.05-E
7.5 LANDING GEAR
The landing gear is a fully retractable, hydraulically operated, tricycle landing gear. Struts
for the landing gear are air oil assemblies.
The hydraulic pressure for the landing gear operation is provided by an electrically powered
hydraulic pump, which is activated by a pressure switch, when the required pressure is
too low. Electrically actuated hydraulic valves, which are operated with the gear selector
switch, provide the required hydraulic pressure for the movement of the landing gear.
The gear selector switch is located on the instrument panel. The switch must be pulled
out before it is moved to UP or DOWN position. Gear extension normally takes
6 - 10 seconds.
When the landing gear is retracted, the main wheels retract inboard into the center wing
and the nose wheel retracts forward into the nose section. Hydraulic pressure on the
actuators keeps the landing gear in the retracted position. A pressurized gas container
acts as an accumulator which keeps the system pressure constant by replacing the volume
lost due to the normal actuator leakages. This prevents a permanent starting of the
hydraulic pump in flight.
Springs assist the hydraulic system in gear extension and locking the gear in the down
position. After the gears are down and the downlock hooks engage, springs maintain force
on each hook to keep it locked until it is released by hydraulic pressure.
The three green lights directly next to the landing gear operating switch illuminate to
indicate that each gear is in the correct position and locked. If the gear is in neither the
full up nor the full down position, a red warning light on the instrument panel illuminates.
Should one power lever be placed in a position below approx. 20 % while the landing gear
is retracted, a warning horn sounds to alert the pilot that the gear is retracted. If installed
a CHECK GEAR caution is indicated on the PFD additionally. The same warning appears
if the flaps move into position LDG (fully extended) while the gear is retracted.
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