Landing Gear

Question 1

Landing Gear

Answer 1

The landing gear for the Canadair Regional Jet is arranged in a standard retractable tricycle configuration. Associated subsystems include: proximity sensing system, nose gear doors, nose-wheel steering, wheel brakes with anti-skid, brake temperature monitoring, main landing gear overheat detection.
Hydraulic system no. 3 powers landing gear and nose wheel steering. The brake system is operated by hydraulic system no. 2 and 3.

Question 2

Main Wheel Bins

Answer 2

Each main gear assembly retracts inward into wheel bins that are recessed into the main landing gear bay. The wheel bins isolate the wheels from the main landing gear bays and prevents tire-thrown debris from damaging the equipment located within the MLG bay. Each wheel bin contains a single loop overheat detection wire to provide an EICAS warning should a wheel overheat.

Question 3

MLG Uplocks and Downlocks

Answer 3

The MLG is held in the up and locked position by mechanical uplocks. With the gear extended, locking mechanisms in the MLG side strut actuators lock the gear in the down position. On the ground, MLG ground locking pins can be inserted into the side strut actuator.

Question 4

MLG Doors

Answer 4

Fixed doors mechanically attached to each of the MLG struts, allow for partial enclosure of the gear when retracted. In the retracted position, brush seals on the door and wheel bins provide an aerodynamic seal between the tires and surrounding aircraft structure.

Question 5

Landing Gear Operation

Answer 5

Normal retraction and extension of the landing gear is initiated by selecting the landing gear lever UP or DN. The retraction or extension signal is sent to the PSS which monitors various landing gear proximity sensor and weight-on-wheels (WOW) inputs. If the correct parameters are met, the PSEU sequentially energizes the appropriate selector valves to retract or extend the landing gear using No.3 hydraulic pressure.