ATA 32 Landing Gear - Issue 6, January 2023 (PDF)

BOMBARDIER DHC 8-400 (PWC PW150) ATA 32 - LANDING GEAR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 244 BOMBARDIER DHC 8-400 (PWC PW150) • • • • LANDING GEAR INTRODUCTION Alternate Extension Wheels and Brakes Steering Sys...

BOMBARDIER DHC 8-400 (PWC PW150) ATA 32 - LANDING GEAR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 244 BOMBARDIER DHC 8-400 (PWC PW150) • • • • LANDING GEAR INTRODUCTION Alternate Extension Wheels and Brakes Steering System Position and Warning The landing gear supports the weight of the aircraft on the ground. It is also used to manoeuvre the aircraft on the ground. The landing gear is electrically controlled, hydraulically operated and mechanically locked. The hydraulically operated nose-wheel steering gives directional control during taxiing, takeoff and landing. Each main wheel has hydraulically powered antiskid brakes. There is also an emergency/park brake system. The tricycle gear is a retractable dual wheel installation. The main gears retract aft into the nacelles and the nose gear retracts forward into the nose section. Gear doors completely enclose the landing gear when it is retracted and partially enclose the gear when it is extended. Flight compartment advisory lights show position of gear doors and down-locks. An aural warning sounds if the gear is not extended and the aircraft is in a landing configuration. A Proximity Switch Electronics Unit (PSEU) monitors and controls the operation of the landing gear components. An alternate landing gear extension method can be used to extend the gear if the primary system fails. There is also an alternate down-lock verification system. The nose-wheel is steerable by either a hand control or through the rudder pedals. The main wheels are equipped with anti-skid multiple disc brakes. The brakes can be controlled by the brake pedals or the EMERG BRAKE lever. The Landing Gear System has the following subsystems: • • • Main Landing Gear and Doors Nose Landing Gear and Doors Landing Gear Extension and Retraction TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 2 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR OVERVIEW TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 3 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR GENERAL DESCRIPTION The main gear retracts aft and the nose gear retracts forward and has steerable nosewheels. The landing gear is operated by the No. 2 hydraulic system and is controlled by the landing gear selector lever on the LANDING GEAR control panel. There is an alternate means of extension for the landing gear in the event that the primary system is not functioning. Advisory lights give extension and retraction fail/safe information. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 4 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 5 of 244 BOMBARDIER DHC 8-400 (PWC PW150) • • • LANDING GEAR MAIN LANDING GEAR AND DOORS Down-lock Release Actuator Up-lock Assembly Alternate Extension Actuator PURPOSE The Main Landing Gear (MLG) absorbs and distributes the landing loads. The MLG and wheels support the aircraft on the ground. The MLG doors supply the fairing for the engine nacelle with the MLG in the retracted position. The main landing gear and doors have the following sub-systems: • • Main Landing Gear Main Landing Gear Doors GENERAL DESCRIPTION Each MLG assembly is installed on the airframe structure in the wheel-well of the related engine nacelle. Each MLG has two wheel and tyre assemblies and retracts rearwards into the aft section of the wheel-well. A retraction actuator is attached to the yoke and to the shock strut to extend and retract the MLG. A lock actuator on the stabilizer brace locks the MLG in the down position. An alternate extension actuator is attached to the airframe structure in the aft section of the wheel-well and to the arm of the yoke. The alternate extension actuator extends the MLG during an alternate extension sequence. An up-lock assembly is attached to the top of the aft section of the wheelwell and locks the MLG in the retracted position. The Main Landing Gear includes the components that follow: • • • • • Shock Strut Drag Strut Stabilizer Brace Yoke Retraction Actuator TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 6 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG AND DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 7 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED GENERAL DESCRIPTION CONTINUED Two doors close off the forward section of the MLG wheel-well. The forward doors are open when the MLG is extended and closed when the MLG is retracted. The doors are opened and closed by adjustable links connected to the drag strut. Two doors close off the aft section of the MLG wheel-well. The aft doors are closed when the MLG is retracted and closed when the MLG is extended. The aft doors are hydraulically actuated. An alternate release arm is used to open the doors during alternate extension of the MLG. The status of the aft doors is shown on the LANDING CONTROL panel in the flight compartment. The MLG include the door components that follow: • • • • • Forward Doors Aft Doors Aft Doors Linkage Mechanism Forward Doors Linkages Aft Doors Actuator TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 8 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG AND DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 9 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED GENERAL DESCRIPTION CONTINUED The shock absorbing unit is located inside the outer cylinder of the shock strut. The unit moves vertically in the shock strut cylinder to absorb shocks. The MLG retract/extend actuator moves the gear into the down lock position. The bottom of the yoke moves backwards and the shock strut pivots around the yoke bottom hinge points and the drag strut hinge points. When the stabilizer brace has unfolded, the lock actuator is hydraulically powered to keep the stabilizer braced locked in the over-centre position. The lock actuator augments the mechanical lock mechanism. The actuator of the MLG wheel-well aft doors is sequenced to open and close the doors. The forward doors of the MLG wheel-well are opened by the downward movement of the drag strut when the extension sequence occurs. The piston of the shock absorbing unit is attached to the shock strut by torque links. The retraction actuator pulls the top of the shock strut up and forwards and the wheels rotate aft into the aft section of the MLG wheel-well. The stabilizer brace folds upwards and pulls the yoke forward. The shock strut hinges on the bottom of the yoke and on the bottom of the drag strut. The MLG up-lock roller engages the up-lock assembly and locks the MLG in the retracted position. The aft door actuator extends to close the aft wheel-well doors. The forward doors of the MLG wheel-well are closed by the upward movement of the drag strut. They are mechanically linked to the drag strut. Proximity sensors on the shock strut use the upper torque link as targets to give a weight-on-wheels or a weight-off-wheels indication to the Proximity Sensor Electronic Unit (PSEU). Proximity sensors located on the outer cylinder indicate a Weight-OffWheels condition to let the MLG retract. A proximity sensor on the aft doors mechanism gives an indication that the doors are closed. Proximity sensors on the stabilizer brace over-centre lock mechanism give an indication that the MLG down-lock is in the downlock position. A proximity sensor on the up-lock assembly gives an indication that the MLG is locked in the retracted position. Extension of the MLG is controlled by the components operation of the retraction and extension system. Hydraulic pressure is supplied to the aft MLG doors actuator to extend and open the doors. The up-lock assembly actuator extends to unlock and release the MLG up-lock roller. The retraction actuator extends to lower the shock strut. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 10 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG AND DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 11 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED GENERAL DESCRIPTION CONTINUED The forward doors are operated by mechanical links attached to the drag strut of the MLG. When the MLG is extended the forward doors are opened mechanically. When the MLG is retracted the doors are closed mechanically. The aft doors are opened and closed by a single hydraulic actuator and a linkage mechanism. The linkage mechanism has a mechanical sequence valve that is connected to the pivot arm by a rod. The door pushrods, lock links, and the tension spring are attached to the pivot arm. The pushrods connect the doors to the pivot arm. The lock links hinge point supplies an over-centre lock for the doors in the closed position. An alternate release arm breaks the over-centre lock of the lock links hinge point to open the doors during alternate extension of the MLG. A proximity sensor sends a signal to the Proximity Sensor Electronic Unit (PSEU). The PSEU sends a signal to the LANDING GEAR Control Panel in the flight compartment, to show the status of the aft doors. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 12 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG AND DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 13 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED AFT DOORS LINKAGE MECHANISM The Aft Doors Linkage Mechanism open and close the doors. The door linkage has two push rods that are attached to the forward hinges of the aft doors and to the pivot arm. The pivot arm is attached to a frame assembly on the left side of the aft section of the wheel-well. The pivot arm has hinge points to form a bell-crank between the push rods and the lock links. The lock links are attached to the bottom of the pivot arm and to the side of the aft section of the wheel-well. The lock links hinge point is pushed into an overcentre position by the actuator to lock the doors in the closed position. The lock links hinge point is pulled from an over-centre position by the actuator to open the doors. The lock links fold and rotate the pivot arm to push open the doors with the push rods. During the alternate extension of the MLG, the alternate release arm rotates to move the lock links from an over-centre position. A tension spring is attached to the pivot arm and to the side of the aft section of the wheel-well. The tension spring turns the pivot arm for the push rods to push open the doors. A proximity sensor is installed on the left side of the aft section of the wheel-well. The proximity sensor sends a signal to the Proximity Sensor Electronic Unit (PSEU). The PSEU sends a signal to the LANDING GEAR control panel, located in the flight compartment, to show the status of the aft doors. When the doors are open the amber L.DOOR and R.DOOR lights come on. The lock links in an over-centre position will show that the doors are closed and locked, and the lights will go off. When the lock links are moved from the over-centre position, the sensor target on the lock links is moved away from the proximity sensor. This will give an indication that the doors are not closed and locked. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 14 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG AFT DOORS LINKAGE MECHANISM DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 15 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED YOKE The yoke assembly is an H-shaped structural component that connects the upper end of the shock strut to the airframe structure in the aft section of the wheel-well. The top of the yoke is attached to the airframe (rear spar) by two lubricated hinge points. The bottom of the yoke is attached to the top of the shock strut by two lubricated hinge points. The yoke attaches to the stabilizer brace at the cross beam with two lubricated hinge points. The retraction actuator cylinder attaches to the cross beam of the yoke with two lubricated hinge points. The rod end of the alternate retraction actuator is attached to lugs at the top of the yoke with lubricated hinge points. The yoke rotates about the top hinge points and the bottom of the yoke moves forward in the wheel-well during the retraction sequence. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 16 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG YOKE DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 17 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED STABILIZER BRACE The stabilizer brace is a two piece folding structural component. The stabilizer brace keeps the yoke and the shock strut in position when the MLG is in the extended or retracted position. The forward section of the stabilizer brace is attached to the airframe structure in the forward section of the wheel-well with two lubricated hinge points. The aft section of the stabilizer brace is attached to the yoke with two lubricated hinge points. The stabilizer brace has an over-centre link subassembly attached between the two sections of the stabilizer brace. The over-centre link subassembly supplies a mechanical lock for the MLG in the down position. The mechanical lock is broken by the lock actuator. The two sections of the link subassembly fold upward to move the bottom of the yoke forward during the MLG retraction sequence. The lock actuator is hydraulically powered at end of extension sequence to augment mechanical locking. The links are moved into the mechanical lock position by the springs. The lock actuator ensures the links remain in the lock position. The lock springs lock the stabilizer brace in the down position when the alternate extension system is in operation. The stabilizer brace has provision for the installation of a ground lock pin when the MLG is extended. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 18 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG STABILIZER BRACE DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 19 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED SHOCK STRUT The shock strut absorbs the shock of aircraft landings. The shock strut outer cylinder is a Y-shaped component with a single stage nitrogen and oil filled shock absorbing piston fitted inside the outer cylinder. Fixed fairings are attached to the forward and aft sides of the shock strut Y-shaped top section and to the outer cylinder. The fairings have an aerodynamic shape and are made from composite material. The anti-skid devices, brake units, and wheel assemblies are attached to a removable and interchangeable axle at the bottom of the shock strut piston. An up-lock roller on the back of the outer cylinder engages the up-lock assembly in the aft section of the wheel-well to lock the MLG in the retracted position. Rotation of the shock strut piston and axle is prevented by two connected torque links. The lower torque link is attached to two lugs on the rear of the shock strut piston. The upper torque link is attached to two lugs on the bottom of the outer cylinder. The top end of the shock strut is attached to the yoke with lubricated hinge points. The lower end of the shock strut outer cylinder is attached to the lower end of the drag strut with a lubricated hinge point. The rod end of the retraction actuator is attached to the top of the shock strut with a lubricated hinge point. Proximity sensor targets on the torque links move as the piston moves to give a WeightOn-Wheels or a Weight-Off-Wheels indication to the PSEU. The proximity sensor and anti-skid wheel speed transducer electrical harnesses and brake hydraulic lines are fitted to the bottom section of the shock strut cylinder. Nitrogen and oil charging and bleeding valves are located on the outer cylinder. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 20 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG SHOCK STRUT DETAILS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 21 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED DRAG STRUT The landing gear pivots about the drag strut upper end hinge during MLG retraction and extension. The drag strut is a fixed length tubular component. The drag strut is attached at the lower end to the shock strut outer cylinder with a lubricated hinge point. The drag strut is attached at the upper end to the airframe structure of the forward section of the wheel-well with a lubricated hinge point. A bracket assembly near the top end of the drag strut is to attach to the linkages of the forward doors of the wheel-well. Brackets attach the electrical harnesses for the proximity sensors and wheel speed transducers, and hydraulic pipes for the brake units along the rear of the drag strut. A grounding point to ground the aircraft during maintenance procedures is fitted to the top of the drag strut. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 22 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG DRAG STRUT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 23 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR by gravity. The torsion spring returns the alternate release arm to the normal position when the alternate release handle in the flight compartment is reset. MAIN LANDING GEAR AND DOORS CONTINUED UP-LOCK ASSEMBLY The Up-lock Assembly holds the MLG during flight in its fully up and locked position without hydraulic pressure. A proximity sensor mounted on the up-lock assembly gives an indication to the PSEU on the status of the up-lock assembly. The target on the lock link moves away from the proximity sensor when the lock link is rotated during the MLG extension sequence. This gives an indication to the PSEU that the up-lock assembly is in the unlocked position. The target on the lock link moves to the proximity sensor when the lock link is rotated during the MLG retraction sequence. This gives an indication to the PSEU that the up-lock assembly is in the locked position. The up-lock assembly is made up of two side plates to form the body of the uplock assembly. The up-lock assembly is made up of a latch assembly, a lock link, an actuator assembly, an alternate release arm, internal extension springs, and a torsion spring. The up-lock assembly is attached to a frame in the top of the aft section of the wheelwell. The latch assembly and the lock link are attached to the body with lubricated hinge points. The latch assembly and the lock link pivot in the body of the up-lock assembly. This action locks the up-lock roller of the MLG in the retracted position. The up-lock roller on the MLG engages the inner face of the latch assembly and the latch assembly pivots into the locked position. The force of the two extension springs keeps the latch assembly fully rotated to lock the MLG in the retracted position. The lock link prevents the latch assembly from rotating to the unlocked position. The lock link is rotated to the unlocked position when the piston of the up-lock actuator extends under pressure from the No. 2 hydraulic system. The latch assembly returns to the locked position when hydraulic pressure is removed from the up-lock actuator. The external compression spring on the up-lock actuator returns the piston to the retracted position when hydraulic pressure is removed from the up-lock actuator. When the main landing gear alternate release handle in the flight compartment is pulled, a cable rotates the alternate release arm. The lower portion of the alternate release arm touches the latch assembly and rotates the latch assembly to release the MLG up-lock roller. The MLG is partially lowered TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 24 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG UPLOCK ACTUATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 25 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED DOWN-LOCK RELEASE ACTUATOR The piston of the down-lock release actuator retracts to break the lock links overcentre position. Further movement folds the stabilizer brace and pulls the yoke forward during the retraction sequence. The piston of the down-lock release actuator extends to hold the lock links into an over-centre position to maintain the stabilizer brace lock position. The down-lock release actuator is of a simple two port design with hydraulic pressure supplied by the No.2 hydraulic system. The down-lock release actuator is attached to the stabilizer brace forward section with lubricated hinge points. The rod end of the down-lock release actuator is attached to the forward lock link of the stabilizer brace assembly with a lubricated hinge point. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 26 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG DOWNLOCK RELEASE ACTUATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 27 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED RETRACTION ACTUATOR The piston of the retraction actuator retracts to retract the MLG. The piston extends to lower the MLG. The retraction actuator is a simple two port design with hydraulic pressure supplied by the No.2 hydraulic system. The retraction actuator is attached to the yoke cross beam lugs with lubricated hinge points. The rod end of the retraction actuator is attached to the top of the shock strut with a lubricated hinge point. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 28 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG RETRACTION ACTUATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 29 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED ALTERNATE EXTENSION ACTUATOR The piston of the alternate extension actuator extends to lower the MLG during the alternate extension sequence. The alternate extension actuator is a one-port design with hydraulic pressure supplied by the hand-pump hydraulic system. The alternate extension actuator attaches to the airframe structure at the top of the wheel-well. The rod end of the alternate extension actuator attaches to the forward side of the yoke with a lubricated hinge point. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 30 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG ALTERNATE EXTENSION ACTUATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 31 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED INLINE RESTRICTORS The inline restrictors are located between the mechanical sequence valves and the retraction actuators. The inline restrictors are two-way fluid fittings that restrict hydraulic flow but not pressure. During an initial sequence of extension or retraction the inline restrictors restrict hydraulic fluid flow to the retraction actuators. This ensures the main landing gear doors will be open before retraction actuators receive full hydraulic pressure and flow. Opening the main landing gear aft doors linkage mechanism causes the mechanical sequence valve to bypass the inline restrictors. Therefore, full hydraulic pressure and flow is now available to the retraction actuators. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 32 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG DOORS INLINE RESTRICTORS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 33 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED LANDING GEAR SELECTOR VALVE The Landing Gear Selector Valve controls pilot pressure to position a spring-centred spool/sleeve type directional control valve to supply system pressure to the UP or DN hydraulic circuits of the landing gear. The landing gear selector valve is a self contained assembly which has two solenoid valves. The landing gear selector valve controls hydraulic pressure to position a directional control valve that is spring centred. The position of the valve controls the supply of hydraulic pressure to either the UP or DOWN hydraulic circuits of the landing gear system. The landing gear system will be configured for either normal retraction or extension. The landing gear selector valve is located in the right wing to fuselage fairing. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 34 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR SELECTOR VALVE – LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 35 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED MLG DOORS SOLENOID SEQUENCE VALVE The MLG Doors Solenoid Sequence Valve lets the hydraulically operated MLG wheelwell doors open and close by porting hydraulic fluid to the door actuators. The MLG doors solenoid sequence valves are located in each landing gear wheelwell on the left side of the nacelle forward of the main landing gear aft doors actuator. The MLG doors solenoid sequence valve is a self contained, bolt-on assembly. The valve is directly operated by a single coil solenoid. NLG DOORS SOLENOID SEQUENCE VALVE The NLG Doors Solenoid Sequence Valve is located in the lower right nose compartment on the outside wall of the NLG bay. The NLG Doors Solenoid Sequence Valve lets the hydraulically operated NLG wheelwell doors open and close. The NLG Doors Solenoid Sequence Valve is a bolt-on assembly with four ports. The valve is directly operated by a single coil solenoid. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 36 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR DOORS SOLENOID SEQUENCE VALVE – COMPONENT DETAILS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 37 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED MAIN GEAR LOCK PINS The Main Gear Lock Pins are inserted in the main gear when extended to prevent the gear from collapsing on the ground. Ground lock pins are supplied for the main gear and an integral ground lock mechanism is controlled from outside the aircraft for locking the nose gear. The main gear lock-pins may be kept in the forward compartment of the forward passenger door. With the gear extended, the pins are inserted into the main gear stabilizer brace assemblies. The main gear lock-pins are pip-pins with an attached REMOVE BEFORE FLIGHT warning flag. The main gear lock-pins are installed in the stabilizer brace over-centre lock. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 38 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG GROUND LOCK PIN LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 39 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR MAIN LANDING GEAR AND DOORS CONTINUED MAIN GEAR DOOR LOCK PIN The Main Gear Door Lock Pins prevent the main gear doors from closing when hydraulic power is applied. The lock pins are used to prevent injury to persons or damage to equipment when repairs are being carried out in the nacelle and landing gear area. The main gear door lock pins are solid steel pins with a REMOVE BEFORE FLIGHT warning flag. The main gear door lock pins are installed in the left side of the aft doors linkage mechanism. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 40 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - MLG HYDRAULIC DOORS LOCK PIN LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 41 of 244 BOMBARDIER DHC 8-400 (PWC PW150) • • • LANDING GEAR NOSE LANDING GEAR AND DOORS The NLG Forward Doors Connecting Rods The NLG Aft Doors The NLG Aft Doors Connecting Rods PURPOSE The Nose Landing Gear (NLG) lets the forward fuselage absorb the shock of landing and gives stability and direction during aircraft taxi. The NLG doors enclose the retracted NLG in the forward fuselage and add to the aerodynamic efficiency of the aircraft The Nose Landing Gear (NLG) doors enclose the retracted NLG in the forward fuselage wheel-well and add to the aerodynamic efficiency of the aircraft. GENERAL DESCRIPTION The NLG is installed in the wheel-well in the nose fuselage, located in front of the forward pressure bulkhead. When the NLG retracts the forward and aft doors enclose it in the wheel-well. A taxi light is installed on the lower right side of the outer cylinder of the shock strut. The GROUND LOCK control handle operates a cable system to engage the downlock safety lever. The nose landing gear assembly has the components that follow: • • • Shock Strut Assembly Drag Strut Assembly Harness Electrical The four NLG doors consist of two hydraulically operated forward doors, and two mechanically operated aft doors. The NLG doors have the components that follow: • The NLG Forward Doors TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 42 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 43 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED NOSE LANDING GEAR RETRACTION ACTUATOR The Nose Landing Gear Retraction Actuator extends and retracts to raise and lower the Nose Landing Gear. The nose landing gear retraction actuator has two ports. The rod end of the piston is installed with bushings and a lubrication fitting. The cylinder end of the actuator has a ball and race with a lubrication fitting. Hydraulic lines are attached to the two ports and are sealed with O-rings. The NLG retraction actuator piston is attached at the top right hand of the NLG shock strut and the cylinder is attached to the aircraft structure. NLG LOCK ACTUATOR The NLG Lock Actuator opens the drag strut lock links. The NLG lock actuator has two ports. The piston is held in the cylinder by a gland nut and a cup washer. Both ends of the actuator have a ball and race with a lubrication fitting. The NLG lock actuator is attached to the NLG drag strut near the lock links. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 44 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG RETRACTION AND LOCK ACTUATORS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 45 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED NODE GEAR GROUND LOCK The nose gear ground lock control handle operates a cable to engage the down-lock safety lever. The ground lock control handle has a momentary action push-button. Pushing the push-button releases the nose gear control handle from the fuselage, and the control handle springs partly out. The control handle must be pulled fully out from the sprung position for it to rotate. Rotating the control lever clockwise ninety degrees to point the chevrons towards the ground, locks the nose gear. The nose gear ground lock is engaged when the down-lock arm of the pivot tube assembly is on the drag strut of the NLG. When the control handle is in and flush with the fuselage, the nose gear is unlocked. When the control handle is fully out and rotated, the nose gear is locked. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 46 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG GROUND LOCK CONTROL HANDLE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 47 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED The two NLG forward doors are hydraulically operated to open before the NLG extends or retracts, and close after the NLG has extended or retracted. The two NLG aft doors are connected to the NLG shock strut and are actuated by the NLG. There is a landing gear door lock pin for the nose hydraulic doors. The door lock pin is installed through the nose landing gear compartment debris guard and locks the toggle link assembly to the bell crank. When inserted it prevents the hydraulic gear doors from closing. The lock pin is stowed in the airstair pins stowage compartment. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 48 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG DOOR LOCK PIN TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 49 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED SHOCK STRUT ASSEMBLY The one stage, nitrogen/oil filled shock strut assembly uses a lever suspension geometry. The shock strut has an outer cylinder, an inner cylinder, a piston assembly, a link and a trailing arm. The trailing arm has a jacking point for jacking the NLG for tyre change or weighing. Refer to Figure 25. Two trunnion arms are installed at the upper rear portion of the outer cylinder, where the trunnion bearings are attached and the NLG is installed. The trunnion bearings are the NLG pivot points during extension and retraction. The retraction actuator is attached to the mounting lugs on the top of the right trunnion arm. At the top forward side of the outer cylinder are two mounting lugs. The lower drag strut is attached to the two mounting lugs. A taxi light is installed on the bottom right side of the outer cylinder. The power steering hydraulic motor and gearbox assembly are installed between the trunnion arms. The NLG steering centring actuator assembly, the steering sensor, and the centring cam are installed on the aft lower side of the outer cylinder. The outer cylinder has attachment points for the electrical harnesses. The Weight On Wheels (WOW) proximity sensors are installed on the inner cylinder above the tow fitting assembly. The piston assembly in the inner cylinder is attached to a link. The link is installed between two lugs on the trailing arm. The link transmits ground loads from the trailing arm to the piston assembly. A low pressure valve is on the top surface of the inner cylinder. The valve is used to service the piston assembly with hydraulic fluid and dry nitrogen. A taxi light is installed on the lower right side of the outer cylinder of the shock strut. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 50 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG SHOCK STRUT ASSEMBLY TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 51 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED DRAG STRUT ASSEMBLY The drag strut assembly stabilizes the shock strut in either the retracted or the extended position. The drag strut assembly has the components that follow: • • • • • • • An upper drag strut A lower drag strut A pivot tube assembly Two spring assemblies A link assembly An upper lock link A lower lock link The two spring assemblies and the pivot tube assembly are installed on the upper drag strut. The pivot tube assembly has six arms: • • • • • Two for the spring assemblies One for the down-lock actuator One for the link assembly One for the emergency up-lock release mechanism One for the ground lock mechanism The lower lock link is installed on the lower drag strut and is connected to the upper lock link. The upper lock link is installed on the upper drag strut and is connected to the lock link assembly. The over centring action of the upper and lower lock links makes a mechanical lock when the gear is in the retracted and the extended positions. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 52 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG DRAG STRUT LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 53 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED ELECTRICAL HARNESS Four electrical harnesses are attached at different places on the shock strut. Two additional electrical harnesses are attached to the drag strut. The four harnesses on the shock strut give power/signal input for the components that follow: • • • • • The taxi light The WOW proximity sensors The steering proximity sensor The steering manifold pressure switches The Rotary Variable Differential Transformers (RVDT) The two harnesses on the drag strut supply electrical power/signal input for the primary and alternate lock proximity sensors. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 54 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 55 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED NLG AFT DOORS The NLG AFT doors provide aerodynamic fairing following nose gear retraction. The two NLG aft doors are connected to the NLG shock strut by two adjustable door linkage assemblies. These doors are open when the NLG is extended and close when the NLG is retracted. Each NLG aft door is hinged to the fuselage at two places. NLG AFT DOORS LINKAGE ASSEMBLIES The two adjustable connecting rods connect the NLG shock strut to the doors for mechanical operation and let the doors be rigged correctly, in the closed position. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 56 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG AFT DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 57 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED NLG FORWARD DOORS The NLG Forward Doors give aerodynamic fairing after NLG retraction and extension. The two NLG forward doors are hinged to the fuselage at two places. The forward hinges form the attachment brackets for the operating mechanism. The operating mechanism has two adjustable connecting rods, an extension spring, a bell crank, a toggle link assembly, a link assembly, a mechanical sequence valve, and a hydraulic actuator. This operating mechanism is attached to the forward wall of the nose-wheel bay and is protected by a removable debris guard. Each door is made up of an inner skin and an outer skin. The inner skin is contoured to give clearance for the nose-wheels in the retracted position. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 58 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG FORWARD DOORS DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 59 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED NLG FORWARD DOORS CONNECTING RODS The two adjustable connecting rods connect the bell crank to the doors. To be rigged correctly the doors must be in the closed position. NLG DOORS ACTUATOR The NLG door actuator extends to break the linkage over-centre and open the doors. The NLG door actuator retracts to over-centre the linkage and close the doors. The NLG door actuator has two ports. The piston is held in the cylinder by a gland nut. NLG DOORS MECHANICAL SEQUENCE VALVE The NLG Doors Mechanical Sequence Valve correctly sequences the NLG up-lock/ down-lock release and the NLG retraction actuators. This prevents the landing gear from travelling through partially opened NLG landing gear doors. The NLG mechanical sequence valve is a bolt-on assembly. The NLG mechanical sequence valve is open when the landing gear is moving between either the fully extended or the fully retracted position. The NLG mechanical sequence valve is closed when the landing gear is locked in either the fully extended or the fully retracted position. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 60 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - NLG FORWARD DOORS LINKAGE TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 61 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR NOSE LANDING GEAR AND DOORS CONTINUED TRAINING INFORMATION POINTS (TIPS) When you do maintenance on the nose landing gear make sure that the nose landing gear ground lock is engaged, the door lock pin is installed and that the hydraulic pressure is shut off. If you do not do this, you can cause injuries to persons and/or damage to the equipment. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 62 of 244 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 63 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION The landing gear Retraction Control System (RCS) controls the hydraulic retraction and extension of the landing gear. It also controls the alternative manual extension of the main landing gear (MLG) and the nose landing gear (NLG). The RCS shows the landing gear and landing gear door status to the flight crew in the flight compartment. The LANDING GEAR selector lever and the Proximity Sensor Electronic Unit (PSEU) control the operation of the landing gear. The No. 2 hydraulic system supplies the power to move the landing gear. GENERAL DESCRIPTION Hydraulic retraction and extension starts when the landing gear selector lever is unlocked and moved to the desired command position. The Proximity Sensor Electronic Unit (PSEU) checks the status of the landing gear and the landing gear doors, and compares it to the command position selected. The PSEU then controls the hydraulic sequences to either fully extend or fully retract the landing gear. The indicator lights installed on the landing gear control panel assembly show the landing gear and landing gear door status. A LDG GEAR INOP caution light is shown on the flight compartment Caution and Warning panel in the event of a system malfunction. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 64 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR EXTENSION AND RETRACTION – COMPONENT DETAILS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 65 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED GENERAL DESCRIPTION The primary extension and retraction system has the components that follow: • • • • • • • • • • • • • • • • • Landing Gear Control Panel Landing Gear Selector Valve MLG Retraction Actuator MLG Down-lock Actuators MLG Up-lock Actuators MLG Doors Actuator MLG Doors Mechanism MLG Doors Mechanical Sequence Valves MLG Doors Inline Restrictors MLG Doors Solenoid Sequence Valve NLG Retraction Actuator NLG Lock Actuator NLG Doors Actuator NLG Doors Mechanism NLG Doors Mechanical Sequence Valve NLG Doors Inline Restrictor NLG Doors Solenoid Sequence Valve TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 66 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR PRIMARY EXTENSION AND RETRACTION – COMPONENT LOCATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 67 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED The status of the landing gear and the landing gear doors is shown by the indicator lights on the LANDING GEAR control panel. A LDG GEAR INOP caution light on the Caution and Warning panel shows a fault in the landing gear retraction and extension system. Normal landing gear operation is controlled by the PSEU as a result of input signals from the landing gear selector lever. The No. 2 hydraulic system supplies the power to move the landing gear. The MLG is designed to retract rearward into the wheel-well. The NLG retracts forward into the nose wheel-well. The four doors of each landing gear hydraulically and mechanically open in sequence with the landing gear movement. The two aft MLG doors and the two forward NLG doors are operated hydraulically by the PSEU. The two forward MLG and the two aft NLG doors are mechanically linked to the landing gear. The doors are opened and closed by the movement of the landing gear. The mechanically actuated landing gear doors stay open while the landing gear are in the extended position. Hydraulically actuated doors are closed at the end of the extension and retraction cycle. There are three conditions required for the PSEU to activate the selector valve. These conditions are as follows: • • • The landing gear selector lever is moved to the UP position The PSEU receives a signal that the aircraft is airborne The NLG is centred The PSEU electrically signals the selector valve to supply hydraulic power to the retract circuit of the landing gear hydraulic system. When the landing gear selector lever is moved to the DOWN position, the PSEU signals the selector valve to supply hydraulic power to the extend circuit of the landing gear hydraulic system. Hydraulic retraction and extension starts when the LANDING GEAR selector lever is moved to the desired position. The PSEU checks the status of the landing gear and the landing gear doors, and compares it to the command selected. The PSEU controls the hydraulic sequences to either fully extend or fully retract the landing gear. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 68 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR CONTROL BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 69 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED The PSEU does sequencing logic for the RCS and gives indications for the landing gear and the landing gear door position. The PSEU interfaces with the landing gear selector lever to turn on the indicator lights on the landing gear control panel. The Landing Gear Control Panel indicator lights are as follows: • • • LEFT, NOSE, RIGHT green lights indicate the gear is down and locked LEFT, NOSE, RIGHT red lights indicate the gear is not locked up, or down L DOOR, N DOOR, R DOOR amber lights indicate landing gear doors are open If the primary down-lock indication fails, an alternate down-lock indication system is available. There are individual green indicator lights for each landing gear, to indicate a down and locked condition. These indicator lights are installed in the flight compartment floor, under the ALTERNATE EXTENSION door. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 70 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - LANDING GEAR SELECTOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 71 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED • • • MAIN LANDING GEAR RETRACTION SEQUENCE • • The main landing gear retraction sequence is as follows: • • • • • • • • • • • • LANDING GEAR lock released selector lever is moved to UP position Landing gear selector valve DN solenoid is de-energized and UP solenoid is energized. (Retraction circuit is pressurized) MLG solenoid sequence valves remains energized by PSEU from end of extension cycle MLG wheel well door actuators open aft doors MLG stabilizer brace over-centre down-locks are released MLG begin to retract slowly through in-line restrictors When MLG wheel doors are approximately 93% open, the mechanical sequence valve is opened and the MLG retracts at full rate MLG engages up-locks MLG solenoid sequence valves are de-energized by PSEU when the up-lock proximity sensors indicate that the MLG are up and locked MLG wheel well door actuators close aft doors. When MLG wheel well doors are approximately 7% closed the mechanical sequence valve is closed Landing gear selector valve UP solenoid is de-energized by PSEU when the associated proximity sensors indicate that all landing gear are up and locked, and all wheel well doors are closed following a 3 second delay • NLG drag strut over-centre down-lock is released NLG begins to retract slowly through in-line restrictors When NLG wheel doors are approximately 92% open, the mechanical sequence valve is opened and the NLG retracts at full rate NLG drag strut over-centre up-lock is energized NLG solenoid sequence valve is de-energized by PSEU when the NGDN and NGLK proximity sensors indicate that the NLG is up and locked NLG wheel well door actuator closes forward doors. When NLG wheel well doors are approximately 8% closed the mechanical sequence valve is closed Landing gear selector valve UP solenoid is de-energized by PSEU when the associated proximity sensors indicate that all landing gear are up and locked, and all wheel well doors are closed following a 3 second delay NOSE LANDING GEAR The nose landing gear retraction sequence is as follows: • • • • LANDING GEAR selector lever is moved to UP position Landing gear selector valve DN solenoid is de-energized and UP solenoid is energized (Retraction circuit is pressurized) NLG solenoid sequence valve remains energized by PSEU from end of extension cycle NLG wheel well door actuator opens forward doors TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 72 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - RETRACTION BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 73 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR valve. When the mechanical sequence valve is in operation hydraulic pressure is supplied to the up side of the MLG retraction actuator. LANDING GEAR EXTENSION AND RETRACTION CONTINUED RETRACTION SEQUENCE When the landing gear is down and locked, the solenoid sequence valves and the down solenoid of the selector valve are kept in an energized condition. This keeps hydraulic pressure on the down side of the retraction actuators. The lock actuators are also used to maintain down-lock the landing gear and to keep the hydraulically actuated wheel-well doors closed. Retraction of the landing gear starts when the LANDING GEAR selector lever is unlocked and moved to the UP position. The MLG starts to travel to the fully retracted position where it is locked in place by the mechanical up-lock. When the PSEU receives the input signals that the MLG is up and locked, the PSEU de-energizes the solenoid sequence valves. This causes the solenoid sequence valves to supply pressure to the close side of the MLG door actuators and close the doors. At approximately 7% reverse travel of the MLG doors, the mechanical sequence valves stop their operation. Inline restrictors bypass the mechanical sequence valves and keep the MLG retraction actuators pressurized to 3000 psi (20684 kPa). Pressure is kept at 3000 psi (20684 kPa) until the landing gear hydraulic system is depressurized upon completion of the retraction cycle. RETRACTION SEQUENCE CONFIGURATION When the LANDING GEAR selector lever is moved to the UP position, the down solenoid of the landing gear selector valve is de-energized. The PSEU makes sure that the aircraft is airborne (WOW1 and/or WOW2) and that the Nose Landing Gear (NLG) is centred. The up solenoid of the landing gear selector valve, now receives electrical power. When the landing gear selector valve receives electrical power, the up solenoid configures the selector valve. This lets hydraulic system pressure flow into the retract side of the landing gear hydraulic system. MAIN LANDING GEAR RETRACTION Hydraulic pressure is supplied through an energized solenoid sequence valve to the open side of the MLG aft door actuators. This causes the MLG aft doors to open. Hydraulic pressure is supplied to each Main Landing Gear (MLG) down-lock release actuator to release the down-lock. The MLG door mechanism operates a mechanical sequence valve to interlock the retraction/extension part of the hydraulic system. At approximately 93% travel of the MLG aft doors, and the MLG aft doors linkage operates the mechanical sequence TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 74 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - UP SELECTION DOORS OPEN TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 75 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED NOSE LANDING GEAR RETRACTION Hydraulic pressure is supplied through an energized solenoid sequence valve to the open side of the NLG forward doors actuator. This causes the NLG forward doors to start to open. Hydraulic pressure is supplied to the NLG up-lock/down-lock release actuator to release the down-lock. At approximately 92% travel of the NLG forward doors, the door linkage operates the mechanical sequence valve. When the mechanical sequence valve opens, hydraulic pressure is supplied to the up side of the NLG retraction actuator. The NLG starts to travel to the fully retracted position where it is locked in place. The proximity sensors make sure that these procedures have been completed. When the PSEU receives the input signals that the NLG is up and locked, the PSEU de-energizes the solenoid sequence valves. This causes the solenoid sequence valves to pressurize the NLG forward doors actuator to close the doors. At approximately 8% close travel of the NLG forward doors, the mechanical sequence valve stops its operation. This action removes pressure from the up side of the NLG retraction actuator. Inline restrictors bypass the mechanical sequence valve and keep the NLG retraction actuator pressurized to 3000 psi (20684 kPa). Hydraulic pressure is kept at 3000 psi (20684 kPa) until the landing gear hydraulic system is depressurized upon completion of the retraction cycle. A proximity sensor senses that the NLG forward doors are closed and sends an input signal to the PSEU. RETRACTION SEQUENCE COMPLETION The MLG and NLG proximity sensors sense that the gear is up and locked and that the MLG and NLG doors are closed. The PSEU gives a three second interval before it de-energizes the up solenoid in the selector valve. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 76 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR AND BRAKES - GEAR UP AND LOCKED DOORS CLOSED TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 32 - LANDING GEAR Issue 6 - January 2023 Page 77 of 244 BOMBARDIER DHC 8-400 (PWC PW150) LANDING GEAR LANDING GEAR EXTENSION AND RETRACTION CONTINUED • • • MAIN LANDING GEAR EXTENSION • • The main landing gear extension sequence is as follows: • • • • • • • • • • • • LANDING GEAR selector lever is moved to DN position Landing gear selector valve DN solenoid is energized by PSEU (Normal extension circuit is pressurized) MLG solenoid sequence valves remains de-energized by PSEU from end of retraction cycle MLG wheel well door actuators open aft doors MLG up-locks are released MLG begin to extend slowly through in-line restrictors When MLG wheel doors are approximately 93% open, the mechanical sequence valve is opened and the MLG extends at full rate MLG stabilizer brace over-centre down-locks are engaged MLG solenoid sequence valves are energized by PSEU when the stabilizer brace proximity sensors indicate that the MLG are down and locked MLG wheel well door actuators close aft doors. When MLG wheel well doors are approximately 7% closed the mechanical sequence valve is closed Landing gear selector valve DN solenoid, MLG solenoid sequence valve, and NLG solenoid sequence valve remain energized by PSEU after extension is complete • NLG drag strut over-centre up-lock is released NLG begins to extend slowly through in-line restrictors When NLG wheel doors are approximately 92% open, the mechanical sequence valve is opened and the NLG extends at full rate NLG drag strut over-centre down-lock is engaged NLG solenoid sequence valve is energized by PSEU when the NGDN and NGLK proximity sensors indicate that the NLG is down and locked NLG wheel well door actuator closes forward doors. When NLG wheel well doors are approximately 8% closed the mechanical sequence valve is closed Landing gear selector valve DN solenoid, MLG solenoid sequence valve, and NLG solenoid sequence valve remain energized by PSEU after extension is complete NOSE LANDING