Extension and retraction of the main undercarriage
- is done by system of 2,5 mm steel cables driven by pulleys and
connected to electromechanical strut LINAK LA30. Time of retraction is
approximately 15 seconds and extension approximately 10 seconds.
Electromechanical strut is placed in the rear cockpit floor, accessible from
baggage compartment.
Locking
Undercarriage legs are secured in retracted position by self-locking
electromechanical struts, in extended position by gas struts and springs.
Electric strut regulates speed of opening. Strut is stopped by proximity
inductive sensors when required position it reached.
Emergency landing gear extension
- is released by mechanical locks controled by bowdens with rods from
front seat, independent for every leg.
A pressure switch for landing gear, connected to pitotstatic system, is
installed in the electrical circuit. Pressure switch is adjusted to speed 115
km/h. This should prevent unintentional retracting of landing gear while
plane is standing on the ground. Control unit does not allow to retract
landing gear, until speed 115 km/h is reached. Extension of landing gear is
not blocked by any switch and works at any speed. Shortcut connector
bypassing this pressure switch is installed on instrument panel for
maintenance purposes. In case the speed drops below 115 km/h and any
of undercarriage legs stay retracted or unlocked, sound warning signal and
flashing of particular LED diode is applied. Opened and locked position of
locking struts on all three legs can be checked through small information windows.
Visual inspection is always superior to electrical signaling and pilot should use it
routinely during undercarriage checkup or in case of any doubts of correct function
of electronic system.
Extension, retraction and signalization of gear
Is controlled by the electronic module designed for this purpose, situated
behind the instrument panel on the parachute partition together with other
electronic modules. Other components of the system are:
- relay switching voltage to the servo of main landing gear
- control and display panel, on the instrument panel, associated with
flaps controll panel
- pressure switch set to 115 km/h, provides signal to control unit
- contactless inductive position sensors, placed in the landing gear
bays, provide informations about landing gear.
- second control and display panel can be optionally placed on the
rear instrument panel.
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