FLAPS HYDRAULIC ACTUATION AND POWER TRANSMISSION - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
A hydromechanical Power Control Unit (PCU) in the fuselage supplies the mechanical power to the flap 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 transmit the mechanical power from the PCU to the offset gearboxes of the actuators. The offset gearboxes then transmit the power through their torque limiters to the rotary actuators, which move the flap transmission system.

The torque limiters control the transmission of torque from the offset gearboxes to keep the torque in the specified limits. The torque limiters prevent the mechanical overload of the rotary actuators.

** ON A/C NOT FOR ALL

2. Component Location

Flap System - Component Location ** ON A/C NOT FOR ALL

Steady Bearings and Torque Shafts - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
6271CM	FLAP ACTUATOR 3	673BB	674	27-54-49
** ON A/C NOT FOR ALL
6211CM	FLAP ACTUATOR 2		574	27-54-49
** ON A/C NOT FOR ALL
6209CM	FLAP LINE GEARBOX		574	27-54-47
6259CM	FLAP LINE GEARBOX		674	27-54-47
** ON A/C NOT FOR ALL
6217CM	FLAP BEVEL GEARBOX		575	27-54-48
6267CM	FLAP BEVEL GEARBOX		675	27-54-48
** ON A/C NOT FOR ALL
6221CM	FLAP ACTUATOR 3	573BB	574	27-54-49
6233CM	FLAP ACTUATOR 4	573BB	575	27-54-49
6283CM	FLAP ACTUATOR 4	673BB	675	27-54-49
** ON A/C NOT FOR ALL
6261CM	FLAP ACTUATOR 2		674	27-54-49
** ON A/C NOT FOR ALL
6206CM	FLAP XMSN TORQUE SHAFT	571AB	572	27-54-45
6207CM	FLAP STEADY BEARING	571AB	572	27-54-44
6208CM	FLAP XMSN TORQUE SHAFT	571AB	572	27-54-45
6210CM	FLAP XMSN TORQUE SHAFT	573AB	574	27-54-45
6213CM	FLAP STEADY BEARING	573BB	574	27-54-44
6214CM	FLAP XMSN TORQUE SHAFT	574BB	574	27-54-45
6215CM	FLAP STEADY BEARING	573CB	574	27-54-44
6218CM	FLAP XMSN TORQUE SHAFT	575AB	575	27-54-45
6219CM	FLAP STEADY BEARING	575BB	575	27-54-44
6220CM	FLAP XMSN TORQUE SHAFT	575BB	575	27-54-45
6223CM	FLAP STEADY BEARING	575DB	575	27-54-44
6225CM	FLAP STEADY BEARING	575DB	575	27-54-44
6226CM	FLAP XMSN TORQUE SHAFT	575DB	575	27-54-45
6228CM	FLAP XMSN TORQUE SHAFT	575DB	575	27-54-45
6229CM	FLAP STEADY BEARING	575EB	575	27-54-44
6231CM	FLAP STEADY BEARING	575FB	575	27-54-44
6232CM	FLAP XMSN TORQUE SHAFT	575FB	575	27-54-45
6256CM	FLAP XMSN TORQUE SHAFT	671AB	672	27-54-45
6257CM	FLAP STEADY BEARING	671AB	672	27-54-44
6258CM	FLAP XMSN TORQUE SHAFT	671AB	672	27-54-45
6260CM	FLAP XMSN TORQUE SHAFT	673AB	674	27-54-45
6263CM	FLAP STEADY BEARING	673BB	674	27-54-44
6264CM	FLAP XMSN TORQUE SHAFT	673BB	674	27-54-45
6265CM	FLAP STEADY BEARING	673CB	674	27-54-44
6268CM	FLAP XMSN TORQUE SHAFT	675AB	675	27-54-45
6269CM	FLAP STEADY BEARING	675BB	675	27-54-44
6270CM	FLAP XMSN TORQUE SHAFT	675BB	675	27-54-45
6273CM	FLAP STEADY BEARING	675CB	675	27-54-44
6275CM	FLAP STEADY BEARING	675DB	675	27-54-44
6276CM	FLAP XMSN TORQUE SHAFT	675DB	675	27-54-45
6278CM	FLAP XMSN TORQUE SHAFT	675DB	675	27-54-45
6279CM	FLAP STEADY BEARING	675EB	675	27-54-44
6281CM	FLAP STEADY BEARING	675FB	675	27-54-44
** ON A/C NOT FOR ALL
6216CM	FLAP XMSN TORQUE SHAFT	573CB	574	27-54-45
6266CM	FLAP XMSN TORQUE SHAFT	673CB	674	27-54-45
** ON A/C NOT FOR ALL
6222CM	FLAP XMSN TORQUE SHAFT	575CB	575	27-54-45
6224CM	FLAP XMSN TORQUE SHAFT	575DB	575	27-54-45
6230CM	FLAP XMSN TORQUE SHAFT	575EB	575	27-54-45
6272CM	FLAP XMSN TORQUE SHAFT	675CB	675	27-54-45
6274CM	FLAP XMSN TORQUE SHAFT	675DB	675	27-54-45
6280CM	FLAP XMSN TORQUE SHAFT	675EB	675	27-54-45
** ON A/C NOT FOR ALL
6212CM	FLAP XMSN TORQUE SHAFT	573AB	574	27-54-45
6262CM	FLAP XMSN TORQUE SHAFT	673BB	674	27-54-45
** ON A/C ALL
6201CM	FLAP-PCU		147	27-54-51
6202CM	FLAP TORQUE SHAFT		147	27-54-45
6203CM	FLAP RIGHT ANGLE GEARBOX		147	27-54-41
6204CM	FLAP XMSN TORQUE SHAFT		147	27-54-45
6205CM	FLAP ACTUATOR 1		148	27-54-49
6252CM	FLAP XMSN TORQUE SHAFT		147	27-54-45
6253CM	FLAP RIGHT ANGLE GEARBOX		148	27-54-41
6254CM	FLAP XMSN TORQUE SHAFT		148	27-54-45
6255CM	FLAP ACTUATOR 1		148	27-54-49
6282CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
** ON A/C NOT FOR ALL
6271CM	FLAP ACTUATOR 3		574	27-54-49
** ON A/C NOT FOR ALL
6221CM	FLAP ACTUATOR 3		274	27-54-49
** ON A/C NOT FOR ALL
6211CM	FLAP ACTUATOR 2		674	27-54-49
** ON A/C NOT FOR ALL
6209CM	FLAP LINE GEARBOX	573AB	574	27-54-47
6259CM	FLAP LINE GEARBOX	673AB	674	27-54-47
** ON A/C NOT FOR ALL
6217CM	FLAP BEVEL GEARBOX	573CB	575	27-54-48
6267CM	FLAP BEVEL GEARBOX	673CB	675	27-54-48
** ON A/C NOT FOR ALL
6233CM	FLAP ACTUATOR 4		575	27-54-49
6283CM	FLAP ACTUATOR 4		575	27-54-49
** ON A/C NOT FOR ALL
6261CM	FLAP ACTUATOR 2		64	27-54-49
** ON A/C NOT FOR ALL
6221CM	FLAP ACTUATOR 3		575	27-54-49
** ON A/C NOT FOR ALL
6206CM	FLAP XMSN TORQUE SHAFT		147	27-54-45
** ON A/C NOT FOR ALL
6216CM	FLAP XMSN TORQUE SHAFT		574	27-54-45
6266CM	FLAP XMSN TORQUE SHAFT		674	27-54-45
** ON A/C NOT FOR ALL
6207CM	FLAP STEADY BEARING		572	27-54-44
6208CM	FLAP XMSN TORQUE SHAFT		572	27-54-45
6210CM	FLAP XMSN TORQUE SHAFT		574	27-54-45
6213CM	FLAP STEADY BEARING		574	27-54-44
6214CM	FLAP XMSN TORQUE SHAFT		574	27-54-45
6215CM	FLAP STEADY BEARING		574	27-54-44
6218CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6219CM	FLAP STEADY BEARING		575	27-54-44
6220CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6223CM	FLAP STEADY BEARING		575	27-54-44
6225CM	FLAP STEADY BEARING		575	27-54-44
6226CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6228CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6229CM	FLAP STEADY BEARING		575	27-54-44
6231CM	FLAP STEADY BEARING		575	27-54-44
6232CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6256CM	FLAP XMSN TORQUE SHAFT		672	27-54-45
6257CM	FLAP STEADY BEARING		672	27-54-44
6258CM	FLAP XMSN TORQUE SHAFT		672	27-54-45
6260CM	FLAP XMSN TORQUE SHAFT		674	27-54-45
6263CM	FLAP STEADY BEARING		674	27-54-44
6264CM	FLAP XMSN TORQUE SHAFT		674	27-54-45
6265CM	FLAP STEADY BEARING		674	27-54-44
6270CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
6273CM	FLAP STEADY BEARING		675	27-54-44
6275CM	FLAP STEADY BEARING		675	27-54-44
6276CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
6278CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
6279CM	FLAP STEADY BEARING		675	27-54-44
6281CM	FLAP STEADY BEARING		675	27-54-44
** ON A/C NOT FOR ALL
6221CM	FLAP ACTUATOR 3		574	27-54-49
** ON A/C NOT FOR ALL
6222CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6224CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6230CM	FLAP XMSN TORQUE SHAFT		575	27-54-45
6272CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
6274CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
6280CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
** ON A/C NOT FOR ALL
6206CM	FLAP XMSN TORQUE SHAFT		572	27-54-45
6268CM	FLAP XMSN TORQUE SHAFT		675	27-54-45
** ON A/C NOT FOR ALL
6212CM	FLAP XMSN TORQUE SHAFT		574	27-54-45
6262CM	FLAP XMSN TORQUE SHAFT		674	27-54-45
** ON A/C NOT FOR ALL
6269CM	FLAP STEADY BEARING		675	27-54-44

** ON A/C NOT FOR ALL

3. System Description

PCU Hydraulic System - Schematic

A. Hydraulic Actuation

Two of the three hydraulic systems supply fluid pressure through a priority valve to the PCU:

the GREEN hydraulic system supplies valve block 23CV
the YELLOW hydraulic system supplies valve block 24CV
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 27-51-00-00) 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

Flap System - Component Location ** ON A/C NOT FOR ALL

Actuator - Typical Installation ** ON A/C NOT FOR ALL

In each wing, the transmission system includes:

torque shafts
a right angle gearbox at the wing root. This changes the drive alignment through 90 degrees for input to the track 1 actuator
a line gearbox. This moves the drive path forward onto the rear face of the false rear spar
a 19 degree bevel gearbox. This puts the drive into line with the rear spar
four actuators. Each actuator consists of an offset gearbox, a torque limiter and a plug-in rotary actuator
a Wing Tip Brake (WTB)
An Asymmetry Position Pick-Off Unit (APPU).

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 both directions. 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 flap mechanism 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.

Drive levers on the actuator output shafts move the flaps through flap link arms. Bolts attach the flap link arms to the flap bottom surface.

To prevent extension or retraction overtravel each drive lever has mechanical stops. Engagement of the stops does not occur at a time of normal operation.

Wing Tip Brakes (WTB) give asymmetry and runaway protection (Ref. AMM D/O 27-51-00-00).
The offset gearbox of the track 4 actuator drives an Asymmetry Position
Pick-off Unit (APPU) (Ref. AMM D/O 27-51-00-00).

Carriages, which roll freely on staight tracks, hold each flap. Track installation is on beams below the wing. Vertical-load rollers and side-load rollers keep the carriages on the tracks. Each carriage has a containment device to hold it on the track if a failure occurs.

The carriages, tracks and beams at tracks 2, 3 and 4 are made almost the same. Attached to the fuselage is track 1, which uses a different configuration as that at tracks 2, 3 or 4. Attached to the flap bottom surface at tracks 2, 3 and 4 are brackets. Connected to the brackets is a linkage which operates the hinged part of the track fairing during flap extension and retraction.

At the end of each track are mechanical stops. The stops prevent retraction overtravel and makes sure that the flap do not disengage at the end of flap extension. Engagement of the stops does not occur at a time of normal operation.

The offset gearbox of the track 4 actuator drives an Asymmetry Position Pick-off Unit (APPU) (Ref. AMM D/O 27-51-00-00).

Carriages, which roll freely on staight tracks, hold each flap. Track installation is on beams below the wing. Vertical-load rollers and side-load rollers keep the carriages on the tracks. Each carriage has a containment device to hold it on the track if a failure occurs.

The carriages, tracks and beams at tracks 2, 3 and 4 are made almost the same. Attached to the fuselage is track 1, which uses a different configuration to that at tracks 2, 3 or 4. Attached to the flap bottom surface at tracks 2, 3 and 4 are brackets. Connected to the brackets is a linkage which operates the hinged part of the track fairing during flap extension and retraction.

At the end of each track are mechanical stops. The stops prevent retraction overtravel and makes sure that the flap does not disengage at the end of flap extension. Engagement of the stops does not occur at a time of normal operation.

Hinge mechanisms connect the trailing edge of the tab surface to the primary surface of the flap. Five hinge mechanisms hold the outboard flap tab to the outboard flap and three hinge mechanisms hold the inboard flap tab to the inboard flap. The tabs and flaps move in relation to each other during extension and retraction.

** 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

Power Control Unit

Power Control Unit - Schematic

A. Power Control Unit FIN: 6201-CM

(1) Description

The flap PCU is a hydro-mechanical 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

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 flaps. When hydraulic pressure is supplied to the retract port, the motor moves in the opposite direction and the flaps retract.

(b) Pressure-Off Brake (POB)

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 flap 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.

Valve Block

The flap 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 supplies a signal to the SFCC so that the SFCC can monitor the position of the control valve spool. 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 slat PCU. Removal of the valve blocks is possible without the 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

Valve Block

The solenoid valves of the PCU are the same and interchangeable with each other and those on the 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) 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.

(g) Position Pick-Off Units

Two PPUs are installed in the flap PCU:

the Instrumentation PPU (IPPU) (Ref. AMM D/O 27-55-00-00)
the Feedback PPU (FPPU) (Ref. AMM D/O 27-51-00-00).

They are the same as the Asymmetry PPU (APPU) (Ref. AMM D/O 27-51-00-00) 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.

(2) Operation

The Slat/Flap Control Computers (SFCC 1 and SFCC 2) (Ref. AMM D/O 27-51-00-00) control the PCU solenoid valves. The SFCC 1 controls and monitors (through the valve block) the operation of the motor 1 and the SFCC 2 does the same for the motor 2.

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 in which the valve spool moves controls the direction in which the motor turns
the distance that the valve spool moves 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 mode, the normal startup sequence and the normal shutdown sequence. Other sequences operate when there is a system failure or if the startup sequence occurs near to the commanded position.

(a) Static Mode

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 spool 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

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.

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 stand-by hydraulic power has a limited flow capacity. At a time of operation with emergency or stand-by 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 flow rate to the motor and thus the work-load on the pump. This prevents the work-load of the slat/flap 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. Right Angle Gearbox 6203CM(6253CM)

Right Angle Gearbox

A right-angle gearbox is installed in each wing. Their gear ratio is 1:1. Bolts attach each right-angle gearbox to the structure.
The input and output shafts have splined ends for connection to the torque shafts of the transmission system. 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. Line Gearbox 6209CM(6259CM)

Line Gearbox

The line 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 right angle gearbox.

D. Bevel Gearbox 6217CM(6267CM)

Bevel Gearbox

The bevel 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 right angle gearbox.

E. Torque Shafts and Steady Bearings

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

Torque Shafts and Steady Bearings - Details

Each torque shaft is a splined/bolted assembly which has, as applicable:

universal joints
flexible joints
a plunging joint.

Universal joints have two forkends connected with a cruciform bearing and can have splined connections or flanged connections. Flanged connections are bolted to flanges on the mating torque shaft and the splined connections connect with mating splines. Splined connections can be one of two types, the movable type ('M'), or the fixed type ('F'). Movable joints are free to move along the splines. Fixed joints have a pin installed to stop any movement. The pins are held in position with a spring clip.

Universal joints let the torque shafts have large angular changes of alignment as they turn.

The flexible joint is an articulating spline-joint assembly that has a male splined coupling and a female splined coupling. The couplings are connected together with a swaged retainer to make a movable joint. The flexible joints let the torque shafts have small angular changes of alignment as they turn.

The plunging joint has a universal joint which moves on splines inside a short drive shaft. The plunging joint gives a flexible joint:

on the output side of the flap 1 actuator
on the input side of the line gearbox.

Each torque shaft assembly has at least one movable end connection. The movable end connection has an indicator groove. This goes out of view when the splines at the connection are correctly engaged.

Steady bearings, which hold the torque shafts, are attached to the structure with bolts. Two types of steady bearing are installed:

a self-aligning ball bearing only
a self-aligning ball bearing and universal joint assembly.

F. Actuator Track 1 6205CM(6255CM)

Actuator - Track 1 ** ON A/C NOT FOR ALL

The actuator is an assembly that has:

an offset gearbox
a rotary actuator.

(1) Offset Gearbox - Track 1

Offset Gearbox ** ON A/C NOT FOR ALL

The offset gearbox casing contains:

a through shaft
the torque limiter
reduction gearing
the rotary actuator.

The power goes from the through shaft through the torque limiter to spur gears. The spur gears move the input shaft of the rotary actuator.

(2) Offset Gearbox - Track 1

Offset Gearbox ** ON A/C NOT FOR ALL

The offset gearbox has:

an actuator housing
a gear cover
a bevel housing
a torque limiter.

The actuator housing is a machined casting which contains the rotary actuator and the torque limiter. The gear cover is bolted to the actuator housing and seals the input side of the actuator.

The bevel housing is bolted to the gear cover and contains an input bevel gear. This engages with a bevel gear shaft that passes through the torque limiter to transmit the output drive to the flap drive system. An input gear is installed on the bevel gear shaft. The input gear engages with an idler gear installed between the input gear and a gear wheel assembly. This gear wheel assembly engages with, and transmits the drive to, the input gear of the rotary actuator.

The input bevel gear is held by one ball bearing and one taper roller bearing. Two roller bearings hold the bevel gear shaft.

The actuator assembly (offset gearbox and rotary actuator) is lubricated with semi-fluid grease and is filled through a vent plug in the bevel housing.

(3) Offset Gearbox - Track 1

Offset Gearbox ** ON A/C NOT FOR ALL

The offset gearbox has:

an actuator housing
an input housing
a torque limiter.

The actuator housing is a machined casting which contains the rotary actuator and the torque limiter. The input housing is bolted to the actuator housing and seals the input side of the actuator. The input housing includes a bevel housing.

The bevel housing contains an input bevel gear. This engages with a bevel gear shaft that passes through the torque limiter to transmit the output drive to the flap drive system. An input gear is installed on the bevel gear shaft. The input gear engages with a double gear which moves two idler gears installed between the input gear and an input gear assembly. The input gear assembly engages with, and transmits the drive to, the input gear of the rotary actuator.

The input bevel gear is held by one ball bearing and one taper roller bearing. Two roller bearings hold the bevel gear shaft.

The actuator assembly (offset gearbox and rotary actuator) is lubricated with semi-fluid grease and is filled through a vent plug in the bevel housing.

(4) Torque Limiter

Offset Gearbox ** ON A/C NOT FOR ALL

Torque Limiter ** ON A/C NOT FOR ALL

The torque limiter has:

a ball ramp device
a friction disk pack spline-mounted to release too much torque through the gearbox casing into the aircraft structure
a spring disk pack that is set to a limit of a minimum of 120 % of the maximum torque for operation
an indicator with a spring clip which usually stays in the retracted position.

The torque limiter is made to stop 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.

(a) Operation

The power input from the torque shaft turns the through shaft of the torque limiter. The power transmits to the reduction gears, then the rotary actuator, through the input gear. If the torque necessary at the input to the rotary actuator is more than the bevel-gear shaft supplies (so the input gear causes resistance):

the balls move up the ramp in the ball and ramp coupling
the input gear moves axially against the spring disks "A"
the movement of the input gear compresses the friction disks against the earthed plates in the friction disk pack
the compression of the friction disk pack causes the input gear to "lock-out"
the pressure on the spring disks "A" pushes the spring cup against the spring disks "B"
the spring cup pushes the plunger
the indicator extends to show that a lock-out torque occured.

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.

(5) Torque Limiter - Track 1

Offset Gearbox ** ON A/C NOT FOR ALL

The torque limiter prevents a torque-overload if there is a malfunction in the flap drive system. The torque limiter has:

a ball ramp device
five earthed plates
six friction discs
two groups of six spring discs
a thrust cup
a lockout indicator.

The ball ramp device gives axial movement of the input gear when the input gear turns at a lower speed than the bevel gear shaft. The device is a coupling made by three balls. These are installed between the input gear and the bevel gear shaft in machined grooves (ramps).

The earthed plates and the friction discs are installed on the input gear. The spring discs and the thrust cup are installed on the bevel gear shaft.

The lockout indicator gives a visual indication that the torque limiter has operated. It has a lockout indicator arm and a plunger. These are operated by movement of the thrust cup.

(a) Operation

Input from the torque shaft is transmitted from the input bevel gear to turn the bevel gear shaft and the input gear through the ball ramp device. Output from the bevel gear shaft is transmitted through torque shafts to the line gearbox. Output from the input gear is transmitted through the idler gear and the gear wheel assembly to the rotary actuator.

During usual operation, the bevel gear shaft, the input gear and the friction discs turn at the same speed. If the torque reaction at the rotary actuator is too high, it causes the input gear to turn more slowly than the bevel gear shaft. This difference in speed causes the input gear to move the balls up the ramps in the bevel gear shaft and the input gear. When this occurs, the input gear moves against the pressure of the spring discs. This compresses the friction discs against the earthed plates and causes the unit to lockout.

When the torque limiter is compressed, the thrust cup moves against the pressure of the spring discs. The thrust cup touches the plunger which extends the lockout indicator arm. This gives a visual indication that the torque limiter has operated. The indicator arm stays extended until it is pushed in manually to cancel the indication.

The system can be set again by operation in the opposite direction.

(6) Torque Limiter - Track 1

Offset Gearbox ** ON A/C NOT FOR ALL

The torque limiter prevents a torque-overload if there is a malfunction in the flap drive system. The torque limiter has:

a ball ramp device
five earthed plates
six friction discs
two groups of six spring discs
a thrust cup
a lockout indicator.

(a) Operation

Input from the torque shaft is transmitted from the input bevel gear to turn the bevel gear shaft and the input gear through the ball ramp device. Output from the bevel gear shaft is transmitted through torque shafts to the line gearbox. Output from the input gear is transmitted through the double gear, the two idler gears and the input gear wheel assembly to the rotary acuator.

During usual operation, the bevel gear shaft, the input gear and the friction discs turn at the same speed. If the torque reaction at the rotary actuator is too high, it causes the input gear to turn more slowly than the bevel gear shaft. This difference in speed causes the input gear to move the balls up the ramps in the bevel gear shaft and the input gear. When this occurs, the input gear moves against the pressure of the spring discs. This compresses the friction discs against the earthed plates and causes the unit to lockout.

When the torque limiter is compressed, the thrust cup moves against the pressure of the spring discs. The thrust cup touches the plunger which extends the lockout indicator arm. This gives a visual indication that the torque limiter has operated. The indicator arm stays extended until it is pushed in manually to cancel the indication.

The system can be set again by operation in the opposite direction.

(7) Rotary Actuator - Track 1

Rotary Actuator - Tracks 1 and 4 ** ON A/C NOT FOR ALL

Bolts attach the rotary actuator to the offset gearbox casing. The gearbox output shaft turns the rotary actuator. A first-stage gear train transmits input torque from the offset gearbox to the power stage of the actuator. The power stage includes nine planet gears held by rings. This gives an equal share of the load between the driven output carrier drive, and the earth annulus gear. The differential gear ratio between the planet gears, the earth annulus gear and the output ring gears gives a high torque/low speed output.

(8) Rotary Actuator - Track 1

Rotary Actuator - Typical ** ON A/C NOT FOR ALL

The rotary actuator is held in the actuator housing of the offset gearbox with two countersunk screws. It is a reduction unit that gives a high torque/low speed output and has:

an input end-cover
an input gear (first stage sun gear)
a short-flanged hub assembly which has a short-flanged hub and a rotating ring gear
first-stage planet gears (three)
an annulus gear assembly
power-stage planet gears (six)
a fixed ring gear
a long-flanged hub assembly which has a long-flanged hub and an output ring gear
an output shaft
an output end-cover.

The input gear and first stage planet gears are installed in bearings in the1 input end-cover and the short-flanged hub assembly. The annulus gear and power-stage planet gears are installed inside the ring gear, between the short-flanged hub and the long-flanged hub assemblies.

Each planet gear has three gears, front, center and rear. The rear gear teeth on the first-stage planet gears engage with the annulus gear. The annulus gear and the rotating ring gear engage with the front gear teeth on the power-stage planet gears. The center gear teeth of the power-stage planet gears engage with fixed ring gear. The rear gear teeth engage with the teeth of the output ring gear.

The output shaft goes through the output end-cover and is splined into the flanged hub assemblies. A retaining plate is attached to the output shaft to keep the output shaft and the input gear in position. The output shaft is connected to the flap drive lever.

(a) Operation

Input from the offset gear box is transmitted through the input gear to first-stage planet gears. The first-stage planet gears turn and transmit the input through the annulus gear assembly to the power-stage planet gears.

The power-stage planet gears engage with the fixed ring gear, the output ring gear and the rotating ring gear. As the fixed ring gear is attached to the wing, the power stage planet gears turn and move around the fixed ring gear. As a result the output ring gear and the rotating ring gear turn. This transmits output through the flanged hubs and the output shaft to the flap drive lever.

G. Actuator Track 2 6211CM(6261CM)

Actuator - Track 2 ** ON A/C NOT FOR ALL

Offset Gearbox - Track 2 ** ON A/C NOT FOR ALL

The actuator is almost the same as the actuator for track 1. Installed on this actuator is a longer type of rotary actuator.

The actuator is an assembly that has:

an offset gearbox
a rotary actuator.

(1) Offset Gearbox - Track 2

The offset gearbox has:

an actuator housing
a torque limiter housing
a torque limiter.

The actuator housing is a machined casting which contains the rotary actuator.

The torque limiter housing is bolted to the actuator housing. It contains an input shaft, the torque limiter and the input gears.

An input gear on the input shaft engages with an idler gear installed between the input gear and a gear wheel assembly. This gear wheel assembly engages with, and transmits the drive to, the input gear of the rotary actuator. Two roller bearings hold the input shaft in the torque limiter housing.

The actuator assembly (offset gearbox and rotary actuator) is lubricated with semi-fluid grease and is filled through a vent plug in the actuator housing.

(2) Torque Limiter - Track 2

The torque limiter prevents a torque-overload if there is a malfunction in the flap drive system. The torque limiter has:

a ball ramp device
five earthed plates
six friction discs
a group of eight spring discs
a thrust cup
a group of six spring discs
a lockout indicator.

The ball ramp device gives axial movement of the input gear when the input gear turns at a lower speed than the input shaft. The device is a coupling made by three balls. These are installed between the input gear and the input shaft in machined grooves (ramps).

The earthed plates and the friction discs are installed on the input gear. The spring discs and the thrust cup are installed on the input shaft.

The lockout indicator gives a visual indication that the torque limiter has operated. It has a lockout indicator arm and a plunger. These are operated by movement of the thrust cup.

(a) Operation

Input from the torque shaft is transmitted by the input shaft to turn the input gear through the ball ramp device.
Output from the input gear is transmmitted through the idler gear and the gear wheel assembly to the rotary actuator.
Output from the input shaft is transmitted by torque shafts, through the bevel gearbox, to the actuator at track 3.

During usual operation, the input shaft, the input gear and the friction discs turn at the same speed. If the torque reaction at the rotary actuator is too high, it causes the input gear to turn more slowly than the input shaft. This difference in speed causes the input gear to move the balls up the ramps in the input shaft and the input gear. When this occurs, the input gear moves against the pressure of the spring discs. This compresses the friction discs against the earthed plates and causes the unit to lockout.

When the torque limiter is compressed, the thrust cup moves against the pressure of the spring discs. The thrust cup touches the plunger which extends the lockout indicator arm. This gives a visual indication that the torque limiter has operated. The indicator arm stays extended until it is pushed in manually to cancel the indication.

The system can be set again by operation in the opposite direction.

(3) Rotary Actuator - Track 2

Rotary Actuator - Typical ** ON A/C NOT FOR ALL

The description and operation for the track 2 rotary actuator is the same as that for the rotary actuator at track 1.

H. Actuator Track 3 6221CM(6271CM)

Actuator - Track 3 ** ON A/C NOT FOR ALL

Offset Gearbox - Track 3 ** ON A/C NOT FOR ALL

The actuator is almost the same as the actuator for track 1. The differences are:

in the offset gearbox are bevel gears as an alternative to spur gears
installed on this actuator is a longer type of rotary actuator, the same as at track 2.

The actuator is an assembly that has:

an offset gearbox
a rotary actuator.

(1) Offset Gearbox - Track 3

The offset gearbox has:

an actuator housing
a gear housing
a bevel gearbox
a torque limiter housing
a torque limiter.

The actuator housing is a machined casting which contains the rotary actuator.

The gear housing is bolted to the actuator housing and contains a bevel gear assembly and a pinion shaft. The pinion shaft is splined and has a bevel pinion at each end. At one end the bevel pinion engages with the bevel gear assembly in the gear housing. At the other, the pinion engages with a bevel gear in the bevel gearbox. The bevel gearbox is bolted to the gear housing.

The torque limiter housing contains an input shaft and a torque limiter and is bolted to the bevel gearbox. The input shaft connects to the bevel gear in the bevel gearbox. Drive is transmitted from the input shaft to the bevel gear through six drive-balls.

The torque limiter housing can be installed in one of two positions. One position is for a LH wing configuration, the other is for a RH wing configuration.

The actuator assembly (offset gearbox and rotary actuator) is lubricated with semi-fluid grease and is filled through a vent plug in the actuator housing.

(2) Torque Limiter - Track 3

The torque limiter prevents a torque-overload if there is a malfunction in the flap drive system. The torque limiter has:

a ball ramp device
five earthed plates
six friction discs
a group of eight spring discs
a thrust cup
a group of six spring discs
a lockout indicator.

The ball ramp device gives axial movement of the hub when the bevel gear turns at a lower speed than the input shaft. The device is a coupling made by three balls. These are installed between the hub and the input shaft in machined grooves (ramps).

The earthed plates and the friction discs are installed on the hub. The spring discs and the thrust cup are installed on the input shaft.

The lockout indicator gives a visual indication that the torque limiter has operated. It has a lockout indicator arm and a plunger. These are operated by movement of the thrust cup.

(a) Operation

Input from the torque shaft is transmitted through the input shaft to turn the bevel gear through the ball ramp device.
Output from the bevel gear turns the pinion shaft which operates the bevel gear assembly and the rotary actuator.
Output from the input drive shaft is transmitted through torque shafts to the actuator at track 4.

During usual operation, the input shaft, the hub, the bevel gear and the friction discs turn at the same speed. If the torque reaction at the rotary actuator is too high, it causes the bevel gear to turn more slowly than the input shaft. This difference in speed causes the hub to move the balls up the ramps in the input shaft and the hub. When this occurs, the hub moves against the pressure of the spring discs. This compresses the friction discs against the earthed plates and causes the unit to lockout.

When the torque limiter is compressed, the thrust cup moves against the pressure of the spring discs. The thrust cup touches the plunger which extends the lockout indicator arm. This gives a visual indication that the torque limiter has operated. The indicator arm stays extended until it is pushed in manually to cancel the indication.

The system can be set again by operation in the opposite direction.

(3) Rotary Actuator - Track 3

Rotary Actuator - Typical ** ON A/C NOT FOR ALL

The description and operation for the track 3 rotary actuator is the same as that for the rotary actuator at track 1.

I. Actuator Track 4 6233CM(6283CM)

Actuator - Typical Installation ** ON A/C NOT FOR ALL

Offset Gearbox - Track 4 ** ON A/C NOT FOR ALL

The actuator is almost the same as the actuator for track 1. The differences are:

in the offset gearbox are bevel gears as an alternative to spur gears
attached to the gearbox casing is the APPU. Included in the offset gearbox is a spur gear to turn the APPU.

The actuator is an assembly that has:

an offset gearbox
a rotary actuator.

(1) Offset Gearbox - Track 4

The offset gearbox has:

an actuator housing
a gear housing
a bevel gearbox
a torque limiter housing
a torque limiter.

The actuator housing is a machined casting which contains the rotary actuator.

The gear housing is bolted to the actuator housing and contains a bevel gear assembly and a pinion shaft. The bevel gear assembly includes a spur gear which engages with a spur pinion. This has a quill drive that engages with the input shaft of the Asymmetry Position Pick-off Unit (APPU). The pinion shaft is splined with a bevel pinion at each end. At one end the bevel pinion engages with the bevel gear assembly in the gear housing. At the other, the pinion engages with a bevel gear in the bevel gearbox. The bevel gearbox is bolted to the gear housing.

The torque limiter housing contains an input shaft and a torque limiter and is bolted to the bevel gearbox. The input shaft connects to the bevel gear in the bevel gearbox. Drive is transmitted from the input shaft to the bevel gear through six drive-balls.

The torque limiter housing can be installed in one of two positions. One position is for a LH wing configuration, the other is for a RH wing configuration.

The actuator assembly (offset gearbox and rotary actuator) is lubricated with semi-fluid grease and is filled through a vent plug in the actuator housing.

(2) Torque Limiter - Track 4

The torque limiter prevents a torque-overload if there is a malfunction in the flap drive system. The torque limiter has:

a ball ramp device
five earthed plates
six friction discs
two groups of six spring discs
a thrust cup
a lockout indicator.

The ball ramp device gives axial movement of the hub when the bevel gear turns at a lower speed than the input drive shaft. The device is a coupling made by three balls. These are installed between the hub and the input shaft in machined grooves (ramps).

The earthed plates and the friction discs are installed on the hub. The spring discs and the thrust cup are installed on the input shaft.

The lockout indicator gives a visual indication that the torque limiter has operated. It has a lockout indicator arm and a plunger. These are operated by movement of the thrust cup.

(a) Operation

Input from the torque shaft is transmitted from the input shaft to turn the bevel gear through the ball ramp device.
Output from the bevel gear turns the pinion shaft which operates the bevel gear assembly and the rotary actuator. The spur gear on the bevel gear assembly transmits an input through the spur pinion and the quill drive to the APPU.

During usual operation, the input shaft, the hub, the bevel gear and the friction discs turn at the same speed. If the torque reaction at the rotary actuator is too high, it causes the bevel gear to turn more slowly than the input shaft. This difference in speed causes the hub to move the balls up the ramps in the input shaft and the hub. When this occurs, the hub moves against the pressure of the spring discs. This compresses the friction discs against the earthed plates and causes the unit to lockout.

When the torque limiter is compressed, the thrust cup moves against the pressure of the spring discs. The thrust cup touches the plunger which extends the lockout indicator arm. This gives a visual indication that the torque limiter has operated. The indicator arm stays extended until it is pushed in manually to cancel the indication.

The system can be set again by operation in the opposite direction.

(3) Rotary Actuator - Track 4

Rotary Actuator - Typical ** ON A/C NOT FOR ALL

The description and operation for the track 4 rotary actuator is the same as that for the rotary actuator at track 1.

J. Flap Carriages

Flap Carriages ** ON A/C NOT FOR ALL

Carriage - Track 1

The carriage at track 1 is machined from aluminium alloy forging. Four vertical-load and two side-load rollers hold the carriage on its track. The rollers are lubricated through grease points on the carriage.

Carriage - Track 2, 3 and 4

The carriages at tracks 2, 3 and 4 are machined from aluminium alloy forgings. All three carriages are almost the same. Six vertical-load and four side-load rollers hold each carriage on its track. The rollers are lubricated through grease points on the carriage. A fail-safe hook keeps the flap on the track if there is a structural failure of the carriage.
Bolts attach the carriages to the flaps. The bolts have eccentrics which let you adjust the flaps.

K. Flap and Track Fairing Operating Mechanism

Flap and Flap Track Fairing - Operation ** ON A/C NOT FOR ALL

Attached to the flap bottom surface, immediately outboard of each track position, is a flap link arm. Bolted to the drive lever, on its related actuator, is the forward end of each link arm. At tracks 1 and 4 are links arms made of machined aluminium. At tracks 2 and 3 are link arms made of machined titanium. The link arms transmit the movement from the rotary actuators to the flap surface.

Attached to the flap bottom surface, at tracks 2, 3 and 4, is an arm which operates the track fairing. Attached to the operating arm is a linkage which operates the moveable track fairing during flap extension and retraction.
Attached to the flap bottom surface, immediately outboard of each track position, is a flap link arm. Bolted to the drive lever, on its related actuator, is the forward end of each link arm. At tracks 1 and 4 are link arms made of machined aluminium. At tracks 2 and 3 are link arms made of machined titanium. The link arms transmit the movement from the rotary actuators to the flap surface.

Attached to the flap bottom surface, at tracks 2, 3 and 4, is an arm which operates the track fairing. Attached to the operating arm is a linkage which operates the moveable track fairing during flap extension and retraction.

Fairings attached to the flap and tab bottom surfaces cover the hinges at the 1A, 1B, 3A, 3B and 3C positions.

L. Inboard and Outboard Tab Operating Mechanism

Flap Tab Hinge Fairings ** ON A/C NOT FOR ALL

The inboard tab is attached to the rear spar of the flap at hinge 1A, hinge 1B and at flap Track 2.
The outboard tab is attached to the rear spar of the flap at the tracks 3 and 4 and at the hinges 3A, 3B and 3C.
When the flaps move, the tabs are operated by a linkage connected from:

the shroud box assembly to the hinge 1A tab attachment bracket
the roller carriages of the tracks 2, 3 and 4 to the tab attachment brackets.

** ON A/C NOT FOR ALL

7. Operation/Control and Indicating

PCU Hydraulic System - Schematic

Valve Block

PCU Operation - Normal Startup Sequence

PCU Operation - Normal Shutdown Sequence

A. Hydraulic Actuation

The SFCC 1 controls the valve block of the GREEN hydraulic system and the related motor on the PCU. The SFCC 2 controls the valve block of the YELLOW hydraulic system and the related motor on the PCU.

NOTE: The operation of the valve block of the GREEN hydraulic system and the related motor is given. The operation of the valve block of the YELLOW 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 flaps. The extend and retract solenoid valves control the direction of the movement of the hydraulic motor.

(1) Flap Extension (Retraction)

(a) When the SFCC 1 receives a command to extend (retract) the flaps, 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 valve spool).

the POB solenoid valve
the extend (retract) side of the motor.

(d) When the valve spool reaches the "pressure on point", a signal from the LVDT causes the SFCC 1 to energize the POB solenoid valve:

the POB releases
the motor starts to turn
the flaps extend (retract).

(e) As the flaps get near to the commanded position:

the FPPU sends a signal to the SFCC 1 when the flaps are 6.69 deg. (FPPU) away from the commanded position
the SFCC 1 energizes the retract (extend) solenoid valve (all three valves are now energized)
the opposite end of the valve spool receives fluid pressure
equal hydraulic forces occur at both ends of the valve spool
the springs continue to move the valve spool in the direction of the neutral position
a restriction of the fluid flow to the motor occurs
a reduction in the motor speed causes a reduction in the rate of flap travel.

(f) When the flaps get to the commanded position:

the FPPU sends a signal to the SFCC 1 when the flaps are 0.177 deg. (FPPU) away from the commanded position
the SFCC 1 de-energizes the extend (retract) solenoid valve and the POB solenoid valve
the POB comes on
when the LVDT shows that the valve spool is 1.5 mm from the neutral position, the SFCC 1 de-energizes the retract (extend) solenoid valve (all three valves are now de-energized)
the fluid flow to the motor stops
the motor stops
the valve spool gets to and stays at the neutral position.

(g) The flaps stay locked by the POB until the next movement is commanded.

B. Power Transmission

The PCU differential gearbox moves the flap transmission system in each wing. The operation of the transmission system is the same for each wing. Only one wing system is specified.

The PCU differential gearbox moves the flap transmission system in each wing. The operation of the transmission system is the same for each wing. Only one wing system is specified.

(1) Flap Extension

(a) The differential gearbox turns the torque shafts, which move the four actuators at the same time, and at the same speed.

(b) Attached to the actuator output shafts are the drive levers. They turn rearwards through an arc of 112 degrees to move the flap link arms.

(c) The flap link arms move the flaps, on their carriages, along the tracks. At the same time, the flap link arms turn the flaps around the lateral pivot axis.

(d) As the flaps extend, the hinged section of the track fairing lowers. This is caused by the effect of the arm which operates the fairing.

(2) Flap Retraction

(a) The torque shaft movement to retract the flaps is the opposite of the movement to extend the flaps.

(3) Flap Extension

(a) The differential gearbox turns the torque shafts, which move the four actuators at the same time, and at the same speed as each other.

(b) Attached to the actuator output shafts are the drive levers. They turn rearwards through an arc of 103 degrees to move the flap link arms.

(c) The flap link arms move the flaps along the tracks on their carriages. Control rods connected between the carriages, hinge 1A and the tabs extend the tabs at the same time. The flap link arms turn the flaps around the lateral pivot axis.

(d) As the flaps extend, the hinged section of the track fairing lowers. This is caused by the effect of the arm which operates the fairing.

(4) Flap Retraction

(a) The torque shaft movement to retract the flaps is the opposite of the movement to extend the flaps.

** ON A/C NOT FOR ALL

8. BITE

Not Applicable

[Rev.10 from 2021] 2026.04.01 06:55:44 UTC