W DOC AIRBUS | AMM A320F

SLATS HYDRAULIC ACTUATION AND POWER TRANSMISSION - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL
1. General
A hydromechanical Power Control Unit (PCU) in the aircraft fuselage supplies mechanical power to the slat transmission system. The PCU has two hydraulic motors. Each motor has a Pressure-Off Brake (POB) and a valve block, which is electrically controlled.

Torque shafts and gearboxes in the fuselage and the wings transmit the mechanical power from the slat PCU to the actuators, which move the slats. There are two actuators for each slat. The actuators are installed on the aircraft structure.

Torque limiters in the transmission system and in the actuators make sure that the load applied to the structure is not too high.

Wing tip brakes give asymmetry and runaway protection (Ref. AMM D/O 27-81-00-00).
** ON A/C NOT FOR ALL
2. Component Location
F Slat System - Component Location
F Steady Bearings and Torque Shafts - Component Location
FIN FUNCTIONAL
DESIGNATION		 PANEL ZONE ACCESS
DOOR		 ATA REF
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6003CM SLAT BEVEL GEARBOX 19 DEG 191 27-84-41
6005CM SLAT T GEARBOX 191 27-84-42
6009CM SLAT BEVEL GEARBOX 191 27-84-43
6011CM SLAT BEVEL GEARBOX 191 27-84-43
6059CM SLAT BEVEL GEARBOX 192 27-84-43
6061CM SLAT BEVEL GEARBOX 192 27-84-43
** ON A/C NOT FOR ALL
6056CM SLAT XMSN TORQUE SHAFT 191EB 192 27-84-45
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6058CM SLAT XMSN TORQUE SHAFT 192EB 192 27-84-45
6060CM SLAT XMSN TORQUE SHAFT 192BT 192 27-84-45
** ON A/C NOT FOR ALL
6015CM SLAT ACTUATOR TYPE A 521EB 521 27-84-48
6027CM SLAT ACTUATOR TYPE B 522AB 522 27-84-49
6029CM SLAT ACTUATOR TYPE B 522CB 522 27-84-49
6033CM SLAT ACTUATOR TYPE B 522FB 522 27-84-49
6035CM SLAT ACTUATOR TYPE B 522KB 522 27-84-49
6037CM SLAT ACTUATOR TYPE B 522NB 522 27-84-49
6039CM SLAT ACTUATOR TYPE B 522QB 522 27-84-49
6041CM SLAT ACTUATOR TYPE B 522SB 522 27-84-49
6045CM SLAT ACTUATOR TYPE B 522UB 522 27-84-49
6063CM SLAT ACTUATOR TYPE A 621CB 621 27-84-48
6065CM SLAT ACTUATOR TYPE A 621EB 621 27-84-48
6077CM SLAT ACTUATOR TYPE B 622AB 622 27-84-49
6079CM SLAT ACTUATOR TYPE B 622CB 622 27-84-49
6083CM SLAT ACTUATOR TYPE B 622FB 622 27-84-49
6085CM SLAT ACTUATOR TYPE B 622KB 622 27-84-49
6087CM SLAT ACTUATOR TYPE B 622NB 622 27-84-49
6089CM SLAT ACTUATOR TYPE B 622QB 622 27-84-49
6091CM SLAT ACTUATOR TYPE B 622SB 622 27-84-49
6095CM SLAT ACTUATOR TYPE B 622UB 622 27-84-49
** ON A/C NOT FOR ALL
6004CM SLAT XMSN TORQUE SHAFT 191BB 191 27-84-45
6006CM SLAT XMSN TORQUE SHAFT 191BB 191 27-84-45
6007CM SLAT STEADY BEARING 191LB 192 27-84-44
6012CM SLAT XMSN TORQUE SHAFT 521AB 521 27-84-45
6016CM SLAT XMSN TORQUE SHAFT 521EB 521 27-84-45
6017CM SLAT STEADY BEARING 521EB 521 27-84-44
6019CM SLAT STEADY BEARING 521EB 521 27-84-44
6021CM SLAT STEADY BEARING 521EB 521 27-84-44
6023CM SLAT STEADY BEARING 522AB 521 27-84-44
6025CM SLAT STEADY BEARING 522AB 522 27-84-44
6031CM SLAT STEADY BEARING 522CB 522 27-84-44
6032CM SLAT XMSN TORQUE SHAFT 522EB 522 27-84-45
6042CM SLAT XMSN TORQUE SHAFT 522SB 522 27-84-45
6044CM SLAT XMSN TORQUE SHAFT 522UB 522 27-84-45
6057CM SLAT STEADY BEARING 192LB 192 27-84-44
6062CM SLAT XMSN TORQUE SHAFT 621AB 621 27-84-45
6066CM SLAT XMSN TORQUE SHAFT 621EB 621 27-84-45
6067CM SLAT STEADY BEARING 621EB 621 27-84-44
6069CM SLAT STEADY BEARING 621EB 621 27-84-44
6071CM SLAT STEADY BEARING 621EB 621 27-84-44
6073CM SLAT STEADY BEARING 622AB 621 27-84-44
6075CM SLAT STEADY BEARING 622AB 622 27-84-44
6081CM SLAT STEADY BEARING 622EB 622 27-84-44
6082CM SLAT XMSN TORQUE SHAFT 622EB 622 27-84-45
6092CM SLAT XMSN TORQUE SHAFT 622SB 622 27-84-45
6094CM SLAT XMSN TORQUE SHAFT 622UB 622 27-84-45
** ON A/C NOT FOR ALL
6026CM SLAT XMSN TORQUE SHAFT 522AB 522 27-84-45
6030CM SLAT XMSN TORQUE SHAFT 522CB 522 27-84-45
6076CM SLAT XMSN TORQUE SHAFT 622AB 622 27-84-45
6080CM SLAT XMSN TORQUE SHAFT 622CB 622 27-84-45
** ON A/C NOT FOR ALL
6008CM SLAT XMSN TORQUE SHAFT 191EB 191 27-84-45
6014CM SLAT XMSN TORQUE SHAFT 521CB 521 27-84-45
6022CM SLAT XMSN TORQUE SHAFT 521AT 521 27-84-45
6024CM SLAT XMSN TORQUE SHAFT 521AT 521 27-84-45
6028CM SLAT XMSN TORQUE SHAFT 522AB 522 27-84-45
6034CM SLAT XMSN TORQUE SHAFT 521HB 522 27-84-45
6036CM SLAT XMSN TORQUE SHAFT 522LB 522 27-84-45
6038CM SLAT XMSN TORQUE SHAFT 522NB 522 27-84-45
6040CM SLAT XMSN TORQUE SHAFT 522QB 522 27-84-45
6064CM SLAT XMSN TORQUE SHAFT 621CB 621 27-84-45
6072CM SLAT XMSN TORQUE SHAFT 621AT 621 27-84-45
6074CM SLAT XMSN TORQUE SHAFT 621AT 621 27-84-45
6078CM SLAT XMSN TORQUE SHAFT 622AB 622 27-84-45
6084CM SLAT XMSN TORQUE SHAFT 621HB 622 27-84-45
6086CM SLAT XMSN TORQUE SHAFT 622LB 622 27-84-45
6088CM SLAT XMSN TORQUE SHAFT 622NB 622 27-84-45
6090CM SLAT XMSN TORQUE SHAFT 622QB 622 27-84-45
** ON A/C NOT FOR ALL
6010CM SLAT XMSN TORQUE SHAFT 191BT 191 27-84-45
6018CM SLAT XMSN TORQUE SHAFT 521EB 521 27-84-45
6020CM SLAT XMSN TORQUE SHAFT 521EB 521 27-84-45
6046CM SHAFT ASSY 522UB 522 27-84-45
6068CM SLAT XMSN TORQUE SHAFT 621EB 621 27-84-45
6070CM SLAT XMSN TORQUE SHAFT 621EB 621 27-84-45
6096CM SLAT XMSN TORQUE SHAFT 622UB 622 27-84-45
** ON A/C ALL
6001CM SLAT-PCU 147 27-84-51
6002CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6013CM SLAT ACTUATOR TYPE A 521 27-84-48
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6003CM SLAT BEVEL GEARBOX 19 DEG 191KB 191 27-84-41
6005CM SLAT T GEARBOX 191BB 191 27-84-42
6009CM SLAT BEVEL GEARBOX 191BT 191 27-84-43
6011CM SLAT BEVEL GEARBOX 191BT 191 27-84-43
6059CM SLAT BEVEL GEARBOX 192BT 192 27-84-43
6061CM SLAT BEVEL GEARBOX 192BT 192 27-84-43
** ON A/C NOT FOR ALL
6058CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6060CM SLAT XMSN TORQUE SHAFT 191 27-84-45
** ON A/C NOT FOR ALL
6056CM SLAT XMSN TORQUE SHAFT 191 27-84-45
** ON A/C NOT FOR ALL
6015CM SLAT ACTUATOR TYPE A 521 27-84-48
6027CM SLAT ACTUATOR TYPE B 522 27-84-49
6029CM SLAT ACTUATOR TYPE B 522 27-84-49
6033CM SLAT ACTUATOR TYPE B 522 27-84-49
6035CM SLAT ACTUATOR TYPE B 522 27-84-49
6037CM SLAT ACTUATOR TYPE B 522 27-84-49
6039CM SLAT ACTUATOR TYPE B 522 27-84-49
6041CM SLAT ACTUATOR TYPE B 522 27-84-49
6045CM SLAT ACTUATOR TYPE B 522 27-84-49
6083CM SLAT ACTUATOR TYPE B 622 27-84-49
6085CM SLAT ACTUATOR TYPE B 622 27-84-49
6087CM SLAT ACTUATOR TYPE B 622 27-84-49
6089CM SLAT ACTUATOR TYPE B 622 27-84-49
6091CM SLAT ACTUATOR TYPE B 622 27-84-49
6095CM SLAT ACTUATOR TYPE B 622 27-84-49
** ON A/C NOT FOR ALL
6063CM SLAT ACTUATOR TYPE A 621 27-84-48
6065CM SLAT ACTUATOR TYPE A 621 27-84-48
6077CM SLAT ACTUATOR TYPE B 622 27-84-49
6079CM SLAT ACTUATOR TYPE B 622 27-84-49
** ON A/C NOT FOR ALL
6063CM SLAT ACTUATOR TYPE A 522 27-84-48
6065CM SLAT ACTUATOR TYPE A 522 27-84-48
6077CM SLAT ACTUATOR TYPE B 522 27-84-49
6079CM SLAT ACTUATOR TYPE B 522 27-84-49
** ON A/C NOT FOR ALL
6066CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6076CM SLAT XMSN TORQUE SHAFT 522 27-84-45
** ON A/C NOT FOR ALL
6067CM SLAT STEADY BEARING 522 27-84-44
6071CM SLAT STEADY BEARING 522 27-84-44
6073CM SLAT STEADY BEARING 522 27-84-44
6075CM SLAT STEADY BEARING 522 27-84-44
** ON A/C NOT FOR ALL
6026CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6030CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6080CM SLAT XMSN TORQUE SHAFT 622 27-84-45
** ON A/C NOT FOR ALL
6004CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6006CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6007CM SLAT STEADY BEARING 192 27-84-44
6012CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6016CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6017CM SLAT STEADY BEARING 521 27-84-44
6019CM SLAT STEADY BEARING 521 27-84-44
6021CM SLAT STEADY BEARING 521 27-84-44
6023CM SLAT STEADY BEARING 521 27-84-44
6025CM SLAT STEADY BEARING 522 27-84-44
6031CM SLAT STEADY BEARING 522 27-84-44
6032CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6042CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6044CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6057CM SLAT STEADY BEARING 192 27-84-44
6062CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6069CM SLAT STEADY BEARING 621 27-84-44
6081CM SLAT STEADY BEARING 622 27-84-44
6082CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6092CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6094CM SLAT XMSN TORQUE SHAFT 622 27-84-45
** ON A/C NOT FOR ALL
6008CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6014CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6022CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6024CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6028CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6034CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6036CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6038CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6040CM SLAT XMSN TORQUE SHAFT 522 27-84-45
6064CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6072CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6074CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6076CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6078CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6084CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6086CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6088CM SLAT XMSN TORQUE SHAFT 622 27-84-45
6090CM SLAT XMSN TORQUE SHAFT 622 27-84-45
** ON A/C NOT FOR ALL
6066CM SLAT XMSN TORQUE SHAFT 621 27-84-45
** ON A/C NOT FOR ALL
6010CM SLAT XMSN TORQUE SHAFT 191 27-84-45
6018CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6020CM SLAT XMSN TORQUE SHAFT 521 27-84-45
6046CM SHAFT ASSY 522 27-84-45
6068CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6070CM SLAT XMSN TORQUE SHAFT 621 27-84-45
6096CM SLAT XMSN TORQUE SHAFT 622 27-84-45
** ON A/C NOT FOR ALL
6067CM SLAT STEADY BEARING 621 27-84-44
6071CM SLAT STEADY BEARING 621 27-84-44
6073CM SLAT STEADY BEARING 621 27-84-44
6075CM SLAT STEADY BEARING 622 27-84-44
** ON A/C NOT FOR ALL
3. System Description
F PCU Hydraulic System - Schematic
A. Hydraulic Actuation

Two of the three hydraulic systems supply fluid pressure through a priority valve to the PCU:
  • the BLUE hydraulic system supplies valve block 25CV
  • the GREEN hydraulic system supplies valve block 26CV
  • the priority valves are set when the pressure drops below 140 bar (2030 psi).

Each valve block controls the flow of hydraulic fluid to the related hydraulic motor and its POB.

Each POB stops and holds the output shaft of the related hydraulic motor when:
  • the solenoids of the related valve block are de-energized because of a normal PCU shutdown sequence
  • there is not enough pressure in the related hydraulic system
  • one of the failures given in (Ref. AMM D/O 27-81-00-00) occurs.

A differential gearbox connects the output shafts of the hydraulic motors and transmits their torque to the power transmission system. If a POB engages and holds its motor, the remaining motor moves the transmission system at half speed but at full torque.
B. Power Transmission

F Slat System - Component Location
F Actuator - Typical Installation ** ON A/C NOT FOR ALL
F Actuator - Typical Installation ** ON A/C NOT FOR ALL
F Slat and Track Fairing-Operation

The slat transmission system includes:
  • torque shafts in the fuselage and wings
  • a 19 degree bevel gearbox which changes the direction in which the drive is aligned
  • a T-gearbox which changes the direction in which the drive is aligned through 90 degrees. This gives an output to each wing
  • two 63.5 degree bevel gearboxes at each wing root. These gearboxes move the drive from below wing level to the wing leading edge
  • ten rotary actuators (two per slat) in each wing.

The torque shafts transmit power from the PCU to the gearboxes and actuators. Universal joints connect the torque shafts and steady bearings support them.

Each input gearbox has a torque limiter which operates in the two directions (extend/retract). Each torque limiter has a lock-out torque value set as necessary for its location. The torque limiters protect the wing structure and the actuators from a torque overload which could occur by a slat transmission failure. A mechanical indicator on each actuator latches if a lock-out occurs. You can set the indicator again when the aircraft is on the ground.

Attachment of the actuators is to housings. Bolts attach the housings to the structure at tracks 2, 3 and 5 thru 12.

Each actuator moves its related track through a pinion. The actuator output shaft moves the pinion which engages with a gear rack. Bolts attach the gear rack to the track. The tracks operate in vertical-load rollers and side-load rollers. The tracks retract through holes in the front spar into sealed containers. The sealed containers make a projection into the fuel tanks.

Tracks 1 and 4 are made almost the same as the moved tracks but without the gear rack. They are to prevent that slat 1 falls away if there is a slat attachment failure.
** ON A/C NOT FOR ALL
4. Power Supply
Not Applicable
** ON A/C NOT FOR ALL
5. Interface
Not Applicable
** ON A/C NOT FOR ALL
6. Component Description
F Power Control Unit

A. Power Control Unit (6001CM)
(1) Description

The slat PCU is a hydromechanical unit. The main body, which is a case, contains a differential gearbox.

The Line Replaceable Units (LRUs) of the PCU are as follows:
  • two hydraulic motors
  • two Pressure-Off Brakes (POB)
  • two valve blocks
  • six solenoid valves
  • two inlet filters
  • one Feedback Position Pick-off Unit (FPPU)
  • one Instrumentation Position Pick-off Unit (IPPU).

(a) Hydraulic Motor

F Hydraulic Motor

Each multi-piston hydraulic motor receives hydraulic pressure from a valve block. The output shaft of the motor is connected to a POB. Hydraulic fluid lubricates the motor. The cylinders of the motor are connected to two ports, referred to as the extend and retract ports.
When the valve block supplies hydraulic fluid to the extend port, the motor moves in the direction necessary to extend the slats. When hydraulic pressure is supplied to the retract port, the motor moves in the opposite direction and the slats retract.
(b) Pressure-Off Brake (POB)

F Pressure-Off Brake

A POB is attached to each hydraulic motor. It holds the output shaft of the hydraulic motor when:
  • the hydraulic motors do not operate
  • the related hydraulic system does not supply sufficient hydraulic power
  • the WTB stops the slat transmission system because of some system failures.

The POB has a multiple friction-disk pack. Splines connect the stators to the POB casing and the rotors to the shaft in the center of the POB. Springs hold the friction disks together. When hydraulic pressure is applied to the POB, the friction disks are disengaged (against the pressure of the springs).
To remove the POB, you must remove the related hydraulic motor first.
(c) Valve Block

F Valve Block

The slat PCU has two valve blocks which are electrically controlled. Each valve block controls the flow of hydraulic fluid to its related hydraulic motor and POB.

The Linear Variable Differential Transducer (LVDT) is installed on one end of the valve block. The LVDT monitors the position of the control valve. Installed on the valve block opposite the LVDT are two directional solenoid valves and one POB solenoid valve. The directional solenoid valves operate as the extend or the retract solenoid valves. The POB solenoid valve operates as the brake solenoid valve.

The valve blocks are interchangeable with those fitted to the flap PCU. Removal of the valve blocks is possible without removal of the PCU from the aircraft.

The primary components of a valve block are:
  • a main control valve
  • an inlet filter
  • five restrictors
  • two check valves
  • a pressure port
  • a return port
  • an electrical connector.

(d) Solenoid Valve

F Valve Block

The solenoid valves of the PCU are the same as and interchangeable with each other and those on the Wing Tip Brake (WTB). Their removal is possible without the removal of the valve blocks from the PCU.

(e) Filter

The inlet filter is installed at the pressure port. Its removal is possible without the removal of the valve block from the PCU.

(f) Position Pick-Off Units

Two PPUs are installed in the slat PCU:

They are the same as the Asymmetry PPU (APPU) (Ref. AMM D/O 27-81-00-00) installed in the transmission system at each wing tip. All PPUs are interchangeable.
An intermediate gear transmits the movement from the differential gearbox to the IPPU and the FPPU.
Removal of the PPUs is possible without the removal of the PCU from the aircraft.
(g) Differential Gearbox

The differential gearbox contains a reduction and differential gear. The reduction and differential gear transmits the movement from the hydraulic motors through the PCU output bevel gear to the flap transmission system. The casing of the differential gearbox also contains the intermediate gear which transmits the movement to the IPPU and the FPPU. On the differential gearbox casing are primary and secondary load points for the attachment of the PCU to the aircraft structure.
(2) Operation

The Slat/Flap Control Computers (SFCC1 and SFCC2) (Ref. AMM D/O 27-81-00-00) control the PCU solenoid valves. The POB, extend and retract solenoid valves, when energized, permit pressure fluid flow:
  • to the POB
  • to the chambers at each end of the control valve.

When the spool of the control valve moves away from the neutral position, the hydraulic system of the aircraft is connected to the related motor as follows:
  • the direction of the valve spool movement controls the direction of the motor rotation
  • the quantity of the valve spool movement controls the speed at which the motor turns.

During normal operation, the valve blocks and the motors operate at the same time. They operate at the same time in the static, full speed or low speed modes.
(a) Static Mode

F PCU Operation - Static Mode

In the static mode:
  • there is no electrical power at all three solenoid valves
  • the centering effect of the springs holds the control valve in the neutral position
  • the lands on the valve spool seal the main pressure and return lines
  • the chambers at each end of the valve and the line to the POB are open to return. The return is through the solenoid valves.
(b) Normal Startup Sequence

F PCU Operation - Normal Startup Sequence

During the normal startup sequence:
  • the SFCC energizes one of the directional (extend or retract) solenoid valves
  • the applicable end of the control valve gets fluid pressure
  • the valve spool moves in response to the increased fluid pressure at its applicable end
  • the LVDT sends a signal to the SFCC to indicate a movement of the valve spool
  • the movement of the valve spool causes the POB solenoid valve to get fluid pressure
  • when the valve spool reaches the "pressure on point", the SFCC energizes the POB solenoid valve to release the POB
  • the hydraulic motor receives fluid flow and starts to turn the transmission
  • with the valve spool fully moved, the motor gets the maximum available fluid flow and turns at full speed.
(c) Normal Shutdown Sequence

F PCU Operation - Normal Shutdown Sequence
During the normal shutdown sequence:
  • electrical power is removed from the drive-direction solenoid when the flaps are 6.69 deg. (FPPU) away from the set position.
  • the opposite direction solenoid is energized at this time.
  • full hydraulic system pressure moves the spool towards the center position. Restrictors control the speed of this movement of the spool.
  • the drive-direction solenoid is now energized again when the spool gets to the "Low Speed" operation position. Spring pressure now moves the spool, at a slower speed, towards the center position. A restriction of hydraulic fluid into the pressure-line upstream of the solenoid valve now controls the speed of movement of the spool.
  • the motor now operates at "Low Speed" because of the decreased size of the pressure and pressure-return connections.
  • electrical power is removed from the drive-direction solenoid and the POB solenoid valve when the flaps are 0.177 deg. (FPPU) away from the set position.
  • when the LVDT indicates that the valve spool is 1.5 mm from the center position the SFCC removes power from the opposite direction solenoid valve.
  • the valve spool moves to the center position and stops.
(d) Pressure Maintaining Function

Emergency or standby hydraulic power has a limited flow capacity. At a time of operation with emergency or standby hydraulic power, it is necessary to prevent a sudden decrease in supply pressure. A sudden decrease in supply pressure can occur because of too much demand by the flap system. This could cause an application of the POB at any time.

The force and the rate of the spring, together with the port area/valve movement property, give the function that maintains the pressure of the valve. As the supply pressure decreases, the valve closes slowly. This reduces the flowrate to the motor and thus the workload on the pump. This prevents the workload of the slat system to cause a sudden decrease of the supply pressure.

(e) Single System Operation

The loss of the hydraulic pressure to one of the two motors causes the POB to apply and hold the motor output shaft. This locks one half of the differential gearbox. The serviceable motor then gives sufficient output torque at half speed, at the gearbox output shaft.
B. Bevel Gearbox, 19 degree (6003CM)

F Bevel Gearbox, 19 degree

The bevel gearbox has a ratio of 1:1. The input and output shafts have reversed lip seals which make sure that unwanted material does not get into the gearbox. The gearbox is filled with grease. There are inspection plugs through which you can examine the lubricant.
C. Tee Gearbox (6005CM)

F T-Gearbox

The T-gearbox has a ratio of 1:1. Bearings, seals and the procedures for lubrication and inspection are almost the same as those used on the 19 degree bevel gearbox.
D. Bevel Gearbox, 63.5 degree (6009CM/6059CM, 6011CM/6061CM)

F Bevel Gearbox, 63.5 degree

The four 63.5 degree bevel gearboxes have a 1:1 ratio and are the same. Bearings, seals and the procedure for lubrication and inspection are almost the same as those used on the 19 degree bevel gearbox.
E. Torque Shafts and Steady Bearings

F Torque Shafts and Steady Bearings - Details ** ON A/C NOT FOR ALL
F Torque Shafts and Steady Bearings - Details ** ON A/C NOT FOR ALL

The torque shafts are made of stainless steel. They have end fittings, which are welded. The end fittings have a flange for a bolted joint or splines for a sliding end connection. Bolts attach universal joints and splined movable joints to the flanges where necessary. The universal joints permit large angular changes of alignment and the splined movable joints allow small angular changes of alignment.

Each shaft has at least one sliding end connection. The external part of the sliding end connection has an indicator groove. It shows when the engagement of the external and internal parts is below a minimum.

Steady bearings, which support the torque shafts, are attached to the structure with bolts.
F. Actuator

F Actuators - Sectional View ** ON A/C NOT FOR ALL
F Actuators - Sectional View ** ON A/C NOT FOR ALL
F Torque Limiter ** ON A/C NOT FOR ALL
F Torque Limiter ** ON A/C NOT FOR ALL
There are two types of actuator in each wing. Those on tracks 2 and 3 are larger in diameter and include more gearing than the other actuators. The assembly and operation is almost the same for all actuators.

Each actuator includes:
  • a cylindrical casing
  • a through shaft
  • a bidirectional torque limiter with latching indicator
  • a sun gear
  • a power output stage. (This includes a compound differential planetary arrangement of six planets, supported by rings)
  • an output shaft which engages the track drive pinion.

The large diameter actuator has a first-stage reduction gear between the sun gear and the power output stage. The differential ratio across the power output stage provides the high torque/low speed operation of the actuators.

Grease fills the actuators for life-time lubrication. It is not possible to lubricate at regular times. Collected moisture drains through bleed holes in the casing. Pivoted cover plates over the bleed holes make sure that unwanted material does not get into the actuator. The cover plates turn to permit the removal of grease from the bleed holes. This helps the collected moisture to drain.
The torque limiter has:
  • a ball ramp device with input and output members
  • a friction disc pack spline-mounted to release too much torque through the gearbox casing into the aircraft structure
  • a spring pack that is set to a limit of a minimum of 120% of the maximum torque for operation
  • an indicator which a spring clip usually keeps in the retracted position.

The torque limiter stops the transmission of too much torque into the output. It also makes sure that the indication of torque peaks, which momentarily engage and release the torque limiter, does not occur.
(1) Operation

Power input to the actuator through-shaft moves the sun gear through the torque limiter.
In the small diameter actuator, the sun gear transmits power directly to the power output stage. The power is then transmitted to the output shaft.
In the large diameter actuator, the sun gear moves the power output stage through the first-stage reduction gear.
When the torque necessary at the actuator output shaft is more than the load value of the torque limiter spring:
  • the output member of the ball ramp moves slowly, which causes the balls to move up the ramp
  • the output member moves axially against spring 'A' into the clearance in the friction disc pack
  • as input torque increases, brake friction in the friction disc pack sends too much input torque through the gearbox casing into the aircraft structure. This limits the output torque
  • more increase in input torque causes more axial movement of the output member against spring 'B'
  • as spring 'B' compresses, the brake friction in the friction disc pack makes sure that the input shaft does not turn
  • the indicator extends to show that lock-out torque has occurred.

The indication of the lock-out torque occurs only:
  • when hydraulic-power-given torque is released through the gearbox casing into the aircraft structure because of too much load downstream.

The system can be set again by operation in the opposite direction. The indicator stays extended until it is cancelled manually.
G. Tracks

F Slat and Track Fairing-Operation

The circular-arc tracks are machined from steel and move in grease-lubricated vertical-load and side-load rollers.
Attached to the forward face of the front spar are two ribs, one inboard and one outboard of the track. Attached to the ribs are the rollers.
The tracks retract through holes in the front spar into sealed containers. The sealed containers make a projection into the fuel tanks.

At each end of each moved track is a fixed stop. On retraction, the forward stops prevent damage to the track containers, slat and leading edge structure. The stops on the rear of the track prevent that the slat falls from the wing when the transmission system is disconnected. Engagement of the stops does not occur during normal operation.

The tracks are of inverted-U section. Tracks 2, 3 and 5 thru 12 have a steel gear rack bolted in the track channel. The gear rack engages with a pinion. Bearings between the track ribs support the pinion. The actuator output shaft moves the pinion.

When tracks 1 and 4 are made, they can have spacers installed in the inverted-U channel. This is to get the correct tolerance. The number of spacers can be between zero and four.

** ON A/C NOT FOR ALL
7. Operation/Control and Indicating
F PCU Hydraulic System - Schematic
F Valve Block
F PCU Operation - Normal Startup Sequence
F PCU Operation - Normal Shutdown Sequence
A. Hydraulic Actuation

The SFCC1 controls the valve block of the BLUE hydraulic system and the related motor on the PCU. The SFCC2 controls the valve block of the GREEN hydraulic system and the related motor.
NOTE: The operation of the valve block of the BLUE hydraulic system and the related motor is given. The operation of the valve block of the GREEN hydraulic system and the related motor is the same.
NOTE: The operation of the valve block is almost the same for the extension and retraction of the slats. The extend and retract solenoid valves control the direction of the movement of the hydraulic motor.
(1) Slat Extension (Retraction)
(a) When the SFCC1 receives a command to extend (retract) the slats, it energizes the extend (retract) solenoid valve of the PCU valve block.
(b) The energized extend (retract) solenoid valve lets hydraulic fluid flow to one end of the spool of the PCU control valve (referred to as the control valve spool).
(c) The control valve spool moves from the neutral position and lets hydraulic fluid flow to:
  • the POB solenoid valve
  • the extend (retract) side of the motor.
(d) SFCC1 energizes the POB solenoid valve:
  • the POB releases
  • the motor moves the differential gearbox in the low-speed mode
  • the slats extend (retract).
(e) As the slats get near to the specified position:
  • the SFCC1 energizes the extend (retract) solenoid valve (all three solenoid valves are now energized)
  • the two ends of the control valve spool receive fluid pressure
  • equal hydraulic forces occur on the control valve spool
  • the springs move the valve spool in the direction of the neutral position
  • a restriction of fluid flow to the motor occurs
  • a reduction of the rate of slat travel occurs.
(f) When the slats get to the specified position:
  • the SFCC1 de-energizes all three solenoid valves
  • the control valve spool moves to the neutral position
  • fluid flow to the motor stops
  • the POB comes on.
(g) The slats stay locked by the POB until the next movement is specified.
B. Power Transmission

The outputs of the PCU hydraulic motor move the differential gearbox. The differential gearbox decreases the speed of rotation and connects the two drives into a single output. A torque shaft transmits power from the differential gearbox to the 19 degree bevel gearbox. A second torque shaft continues the drive to the input gear of the T-gearbox. In the T-gearbox the direction in which the drive is aligned is changed through 90 degrees. The change of direction is by a single transverse output shaft moved through 1:1 bevel gearing by the gearbox input.

Downstream of the T-gearbox, the operation of the transmission system is the same for each wing. Only one wing system is specified.
Torque shafts from the T-gearbox transmit the drive to the lower of two 63.5 degree bevel gearboxes. The 63.5 degree bevel gearboxes are installed at the wing root between RIB 1 and the fuselage. A single torque shaft connects the two 63.5 degree gearboxes.

The 63.5 degree gearboxes transmit the movement from below the center wing box into the wing leading edge. The movement is transmitted without a decrease in speed. From the upper 63.5 degree gearbox more torque shafts continue the movement through the ten rotary actuators. The movement stops at the APPU (Ref. 27-81-00) in the wing tip.

When the torque shaft turns, it moves all the gearboxes and the input shafts of the rotary actuators. The movement at the gearboxes and rotary actuators occurs at the same time and at the same speed. The rotary actuators give the necessary torque and speed decrease to move the slats at the specified rate.
** ON A/C NOT FOR ALL
8. Bite
Not Applicable
[Rev.10 from 2021] 2026.04.01 06:56:01 UTC
"Aviabrain" 2025