The control and indication system controls the movement of the spoiler control surfaces for flight operations. It also gives data on the position of the spoiler control surfaces to the flight crew.

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The flight spoiler control lever (FSCL) is found on the center pedestal in the flight compartment.

The FSCL contains four rotary variable-differential transducers (RVDTs). The RVDTs are electrically connected to the spoiler electronic-control units (SECUs).

The control lever has ten different positions, from retracted to fully extended (STOW to EMER). A button in the handle of the control lever moves the control lever from the locked retracted (STOW) position. This button also moves the control lever to the locked extended (EMER) position.

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There are two electronic line replaceable units, identified as SECU 1 and SECU 2, installed in mounting trays in the RH equipment rack. There are two swivel handles on the front of the SECU to help remove the SECU from the mounting tray.

The SECUs give signals to the spoiler power-control units (PCUs) and the ground-spoiler selector valves. The SECUs also supply EICAS messages, maintenance data and flight-data recorder (FDR) data.

SECU 1 and SECU 2 interchange data through a one function ARINC 429 bus. The internal structure of each SECU has a command and monitor path. The internal structure of each SECU also has built-in test.

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The control and indication system for the spoilers has two SECU trays. They are installed in the RH equipment rack.

Two hold-down clamps on the tray engage the hold-down hooks on the SECU and attach the SECU to the tray. The connector at the rear of the tray gives the interface from the SECU to the aircraft system wiring.

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There are four spoiler proximity sensors, one for each ground spoiler. They are installed in the trailing edge of the inboard sections of the wing.

The spoiler proximity sensor is a cylinder with an electrical connector at one end and a sensor at the other end. It uses a magnetic steel target to sense the position of the ground spoiler panel.

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There are four MFS RVDTs, one for each multi-function spoiler. They are installed in the trailing edge of the middle sections of the wing.

Each MFS panel installation contains a linkage which operates a RVDT. The SECU changes the RVDT electrical output to the panel position, and monitors the MFS spoiler panel position.

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The SECUs receive data signals from the four RVDTs in the FSCL (lever position) and the flap control unit (flap position). The SECUs use this data to tell the ground-spoiler selector valves (GSSVs), in the left and right wheel-wells, when to operate the PCUs as a function of FSCL and flap position. The GSSVs give or cut off hydraulic pressure to the PCUs. The PCUs then move the MFS control surfaces.

The SECUs receive data signals from the wheel speed transducer and the weight on wheels (WOW) spoiler proximity sensors. The SECUs also receive data from the radio altimeter transceiver (radio altitude) and the throttle lever RVDTs (engine power position). The SECUs use this data to tell the GSSVs when to operate the GSAs as a function of altitude and aircraft speed. The GSAs then move the ground-spoiler control surfaces.

The pilot uses the FSCL to control proportional lift dumping of the aircraft. Proportional lift-dumping commands are transmitted to the SECUs from the FSCL through four synchronized RVDTs. This data, with roll assist inputs and the flap position, calculates the multi-function spoiler commands. The MFS positions are also changed continuously by the roll-control input module (RCIM) found in the control wheels.

The two SECUs control the spoiler functions. The SECUs connect to the power control units (PCUs) of the multi-function spoilers through the ground-spoiler selector valves (GSSVs). The SECUs also connect to the ground-spoiler actuators (GSAs) of the ground spoilers through the GSSVs.

One hydraulically energized and electrically controlled PCU controls the position of each multi-function spoiler. An electro-hydraulic servo-valve (EHSV) changes an electrical signal to a hydraulic input. A linear variable-differential transformer (LVDT), which is a part of the PCU, sends a position signal.

Each ground spoiler is moved to the extended or retracted position by a hydraulically energized ground spoiler actuator (GSA). A GSSV controls the hydraulic power to a pair of GSAs. Each GSSV also has a Multi-Function Spoiler Shut-Off-Valve (MFS SOV) which controls hydraulic power to a pair of MFS actuators.

Two of the three solenoid valves of the GSSV energize to extend the pair of ground spoilers. Retraction of the ground spoilers occurs when electrical power is removed from one or two of the solenoids. The third solenoid valve of the GSSV energizes to extend the pair of Multi-Function Spoilers (MFSs). Retraction of the MFS occurs when electrical power is removed from the third solenoid.

SECU 1 controls PCUs 2 and 7 and ground spoiler actuators 4 and 5. SECU 1 uses electrical power from Junction Box No. 1 (LEFT MAIN 28 VDC) and the left hydraulic system. SECU 2 controls PCUs 1 and 8 and ground spoiler actuators 3 and 6. SECU 2 uses electrical power from Junction Box No. 2 (RIGHT MAIN 28 VDC) and the right hydraulic system.

If one electrical power system is unserviceable, the operation of one pair of multi-function spoilers stops. It also stops the operation of one pair of ground spoilers. If one hydraulic power system is unserviceable, the operation of one pair of multi-function spoilers stops. It also stops the operation of one pair of ground spoilers.

Each ground spoiler (GS) panel has a spoiler proximity sensor that connects with it. The spoiler proximity sensors give indications that the panel is extended from the retracted position. The position of the spoiler proximity sensor is calculated by the PSEU. The sensor positions are the target near (stowed), and the target far (deployed). ARINC labels on the SECU-1 and SECU-2 high-speed buses (and the L-GP-5 and R-GP-5 buses) send the positions (stowed/deployed) for the GS panels, as calculated by the PSEU.

Each MFS panel installation contains a linkage which operates a RVDT. The SECU changes the RVDT electrical output to the panel position, and monitors the panel position. The SECU also monitors the panel position identified by a LVDT in each MFS actuator. A panel problem is identified when outputs of the LVDT in the actuator and the RVDT on the panel are different. ARNIC labels on the SECU-1 and SECU-2 high-speed buses send the positions for the MFS panels, as calculated from the MFS RVDTs.

The ROLL SPOILERS push-button-annunciator (PBA) is found on the GND/ROLL SPOILERS control-panel. If the aileron control circuit is not locked but the pilot's control wheel is locked, the pilot must then push the ROLL SPOILERS PBA. This will give control of the ailerons to the copilot and stop the roll aid function of the multi-function spoilers. When the PBA is pushed, the ROLL SPOILERS OFF light comes on. If the pilots wheel becomes unlocked and the PBA is pushed again, the ROLL SPOILERS OFF light goes off. Also, the roll aid function of the multi-function spoilers will start again.

When the rotary switch, on the GND/ROLL SPOILERS control-panel, is set to the OFF position, it disarms the ground spoiler function. In the AUTO position the switch automatically arms the ground spoiler function. This function arms the ground spoiler for landing and rejected take-off with the throttle lever angle and the wheel speed inputs from the brake control unit (BCU). When the switch is set in the MANUAL ARM position, it arms the ground spoiler function without the throttle lever angle and wheel speed inputs.

The SECUs supply MFS and the ground spoiler position indications to the FLIGHT CONTROLS synoptic page of the multi-function display and to the EICAS display. These displays show the MFS and ground spoiler movements in the up or down positions on a scale with arrows. The arrows show the MFS position in degrees from 0 degree (stowed) to 45 degrees (fully deployed). The arrows show the ground spoiler position at 0 degree (stowed) or 60 degrees (fully deployed).

The MFS and the ground spoiler arrows show red when the CONFIG SPOILERS warning message comes on. The MFS arrows show amber when there is a unserviceable condition with the spoiler or the FLT SPOILERS DEPLOY caution message comes on. The ground spoiler arrows show amber when the ground spoiler is deployed before touchdown or it is deployed and unserviceable. When there is no unserviceable MFS spoiler condition or no messages shown then the arrows show green. When there is no ground spoiler deployed before the touchdown, or no deployed unserviceable ground spoiler, the arrows show green.

The SECUs receive signals from the FSCL and the sensors. The SECUs use this data to tell the ground-spoiler selector valves when to operate the ground spoiler actuators (GSAs). The SECUs also use this data to tell the ground-spoiler selector valves when to operate the PCUs.

The CONFIG SPOILERS warning message will show when the aircraft is on ground and the spoilers are not correctly configured for take-off.

The FLT SPOILERS DEPLOY caution message will show when the flight spoilers are deployed below 500ft (not on ground) and/or the throttles are above idle (not on ground).

The FLT SPOILERS FAIL caution message will show when the flight spoilers have failed. The FLT SPOILERS FAULT caution message will show when the inboard or outboard flight spoilers have failed.

The GND SPLRS NOT ARMED caution message will show when the ground spoilers are not armed and not set OFF.

The GND SPOILERS FAIL caution message will show when the ground spoilers have failed. The ROLL SPOILERS FAIL caution message will show when the roll assist function has failed.

The ROLL SPOILERS FAULT caution message will show when the inboard or outboard roll spoilers have failed.

The ROLL SPOILERS OFF caution message will show when the roll spoiler switch is set to OFF and the roll disconnect switch is not set to disconnect.

The SPOILERS FAIL caution message will show when the spoilers have failed.

The SPOILERS FAULT caution message will show when one or more of the spoiler PCU panels have failed, or one or more of the ground spoilers is up prior to touchdown.

The SPOILERS FAULT advisory message will show when a fault that causes the loss of redundancy has occurred in the spoiler system but does not affect spoiler operation.

The GND SPOILERS OFF status message will show when the ground spoilers are set OFF.

The ROLL SPOILERS OFF status message will show when the roll spoiler switch is set to OFF and the roll disconnect switch is set to disconnect.

The EICAS messages that follow are related to the control and indication system:

EICAS MESSAGE(S)	LEVEL (COLOR)
CONFIG SPOILERS	WARNING (red)
FLT SPOILERS DEPLOY	CAUTION (amber)
FLT SPOILERS FAIL	CAUTION (amber)
FLT SPOILERS FAULT	CAUTION (amber)
GND SPLRS NOT ARMED	CAUTION (amber)
GND SPOILERS FAIL	CAUTION (amber)
ROLL SPOILERS FAIL	CAUTION (amber)
ROLL SPOILERS FAULT	CAUTION (amber)
ROLL SPOILERS OFF	CAUTION (amber)
SPOILERS FAIL	CAUTION (amber)
SPOILERS FAULT	CAUTION (amber)
SPOILERS FAULT	ADVISORY (cyan)
GND SPOILERS OFF	STATUS (white)
ROLL SPOILERS OFF	STATUS (white)

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The control and indication system has interfaces with the components and systems that follow:

• Control Wheel
• Roll Disconnect Microswitch
• Flap Control Unit (FCU)
• Multi Function Spoiler
• Ground Spoiler
• Ground Spoiler Selector Valve
• GRD/ROLL SPOILERS Control Panel
• Left and Right Hydraulic Systems
• Engine Indicator and Crew Alerting System (EICAS)
• Data Concentrator Unit (DCU)
• Input/Output Concentrator Unit (IOC) 
• Brake Control System
• Position Indicating System
• Proximity Sensor Electronic Unit (PSEU)
• Air Data Computer
• Radio Altimeter System 
• Full Authority Digital Engine Control (FADEC) System

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Component Location Index
IDENT	DESCRIPTION	LOCATION	IPC REF
A6	FLIGHT-SPOILER CONTROL LEVER	ZONE(S) 211	27−61−01
A118	SPOILER ELECTRONIC-CONTROL UNIT (SECU) NO.1	ZONE(S) 222	27−61−05
A119	SPOILER ELECTRONIC-CONTROL UNIT (SECU) NO.2	ZONE(S) 222	27−61−05
-	SPOILER ELECTRONIC-CONTROL UNIT (SECU) TRAY	ZONE(S) 222	27−61−07
PX43	PROXIMITY SENSOR (LH)	ZONE(S) 561	27−61−09
PX13	PROXIMITY SENSOR (LH)	ZONE(S) 562	27−61−09
PX44	PROXIMITY SENSOR (RH)	ZONE(S) 661	27−61−09
PX14	PROXIMITY SENSOR (RH)	ZONE(S) 662	27−61−09

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