The switching control system supplies the flight crew with engine control and display functions. The pilot uses the switching system to operate the start and ignition cycle of the engine, and to activate or deactivate some of the engine power control functions. The system also starts a fire extinguishing action from the flight compartment, if there is a fire in one of the engines or auxiliary power unit (APU).

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On A/C 20501 to 20874 Pre SB 350-22-002:

The engine control panel is installed in the center pedestal on the copilot's side. The panel is attached to the structure with four quick-release fasteners. It is connected to the aircraft systems through two receptacles located at the rear of the panel. At the front, the engine control panel has an overlay panel that is supplied with 5 V pulse width modulation (PWM), from the integral lighting controller.

The engine control panel has eight pushbutton annunciators (PBAs), one pushbutton, and three rotary switches that supply an interface for the following engine control functions:

• Control of the engine start and ignition procedures
• Control of the engine synchronization function
• Activation of the automatic power reserve (APR) function
• Activation of the MACH HOLD function
• Activation of the EVENT record function

The engine control panel is also an interface for the following engine/APU fire extinguishing functions:

• Display of engine and APU fire indication
• Engine and APU shutdown
• Command for the discharge of the fire bottles

For the engine control functions, the engine control panel has the following switches, PBAs, and push button:

• L STARTER rotary switch
• IGNITION PBA
• R STARTER rotary switch
• AUTO APR PBA
• AUTO SYNC rotary switch
• MACH HOLD PBA
• EVENT pushbutton

For the engine/APU fire extinguishing functions, the engine control panel has the following PBAs:

• L ENG FIRE
• APU FIRE
• R ENG FIRE
• FIRE EXT 1
• FIRE EXT 2

On A/C 20937 and Subs and On A/C 20875 to 20936 Post SB 350-22-002:

The engine control panel is in the center pedestal on the copilot side. The panel is attached to the structure with four quick-release fasteners. It is connected to the aircraft systems through two receptacles located at the rear of the panel. At the front, the engine control panel has an overlay panel that is supplied with 5 V pulse width modulation (PWM), from the integral lighting controller.

The engine control panel has eight pushbutton annunciators (PBAs), one pushbutton, and three rotary switches that supply an interface for the following engine control functions:

• Control of the engine start and ignition procedures
• Control of the engine synchronization function
• Activation of the automatic power reserve (APR) function
• Activation of the EVENT record function

The engine control panel is also an interface for the following engine/APU fire extinguishing functions:

• Display of engine and APU fire indication
• Engine and APU shutdown
• Command for the discharge of the fire bottles

For the engine control functions, the engine control panel has the following switches, PBAs, and push button:

• L STARTER rotary switch
• IGNITION PBA
• R STARTER rotary switch
• AUTO APR PBA
• AUTO SYNC rotary switch
• EVENT pushbutton

For the engine/APU fire extinguishing functions, the engine control panel has the following PBAs:

• L ENG FIRE
• APU FIRE
• R ENG FIRE
• FIRE EXT 1
• FIRE EXT 2

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The engine control panel lets the pilot control the engine start cycle and the engine power. It also lets the pilot do engine or APU shutdown if a fire condition occurs.

Engine Controls

Engine Start

The L/R STARTER rotary switches and IGNITION PBA are used for engine start procedures. These PBAs and this switch are used together with the ENGINE RUN switches that are located on the throttle quadrant assembly (TQA).

L/R Starter

The L STARTER and R STARTER switches are momentary switches that have CRANK, OFF, and START positions. When the L STARTER or R STARTER switch is set to CRANK, it causes the full authority digital engine control (FADEC) system to turn the applicable left or right engine (crank or motor) with no ignition. When the L STARTER or R STARTER switch is set to START, and held in that position for one second, it causes the engine FADEC controller to start the applicable engine.

The L STARTER and R STARTER switches are connected to the engine starting system and to the cabin pressure control system. The integrated air system (IAS) controller monitors the position of the L or R STARTER switch. When the L STARTER or R STARTER switch is not in the OFF position, bleed air to other aircraft systems is limited to help the start operation of the applicable engine. These operating conditions of the bleed-air system continue until the engine FADEC controller sends a signal to stop the starter.

IGNITION

Operation of the ignition system is controlled in the automatic or manual mode. In the automatic mode, the electronic control units (ECUs) supply the ignition that is necessary for automatic engine start and also in relation to flameout conditions.

In the manual mode, ignition is controlled by the pilot with the IGNITION PBA. The IGNITION PBA controls the activation of the two exciter channels of the ignition system.

When the IGNITION PBA is in normal position, the two ignition exciter channels are activated one after the other between the starts. When the exciter channels operate in this sequence, they let the system show possible fault condition. But when the IGNITION PBA is pushed (the switch light comes on to show ON status), the two channels are activated at the same time during the start operation.

Engine Power Control

The AUTO APR PBA, AUTO SYNC switch, and MACH HOLD PBA are used to control and adjust engine power. The EVENT pushbutton is used to start manually a record function.

AUTO APR

The AUTO APR is a PBA with a guard which lets the pilot inhibit the automatic power reserve (APR) function. The APR function automatically supplies adjustment of the engine thrust setting when an engine fail condition is found during takeoff. The AUTO APR PBA is a two position PBA. The light shows the switch position status (ARMED or OFF). The default position is the ARMED position. In this position, the APR function is enabled. The pilot can set the PBA to the OFF position to inhibit the automatic transition to APR engine power setting.

AUTO SYNC

The AUTO SYNC switch lets the pilot do the selection of the engine automatic synchronization mode. The switch has three positions: N1, N2, and OFF. When the AUTO SYNC is in the OFF position, the engines are not synchronized. When the switch is set to N1 or N2 position and the two engines display cruise (CRZ) or climb (CLB) rating, the engines are synchronized. In the synchronized mode, the engine with the higher N1 compensation (or the left engine when N1 compensation of the two engines is the same) is the master engine.

When the pilot sets the switch at N1, the slave engine uses N1 set point from the master engine as its own set point. When the pilot sets the switch at N2, the slave engine calculates the difference between its measured N2 and the measured N2 from the master engine. The slave engine adds the difference to the N1 set point.

MACH HOLD ( Only On A/C 20501 to 20936 Pre SB 350-22-002)

The MACH HOLD PBA lets the pilot engage or disengage the Mach hold function. The Mach hold function supplied by the engine FADEC controller, adjusts the engine power to keep the aircraft Mach number. The pilot pushes the momentary MACH HOLD PBA to activate the Mach hold function, and the light comes on. To disengage the Mach hold function, the pilot pushes the MACH HOLD PBA, and the light goes off.

EVENT

The EVENT pushbutton records engine parameters data associated with an event observed by the flight crew. The pilot pushes the EVENT pushbutton to manually start the event record function. For more details about the event record function, see the engine condition–fault reporting (EC–FR) system.

Engine/APU Fire Condition

Five PBAs are used for engine and APU fire indication and fire extinguishing. The first three PBAs are also used by the flight crew as an auxiliary control to stop the engine or the APU.

L ENG FIRE, APU FIRE, and R ENG FIRE

The L ENG FIRE, APU FIRE, and R ENG FIRE PBAs are latching type PBAs with guards. These switches have red light-emitting diodes (LEDs).When the fire detection system reports a fire in one of the engines or in the APU, the applicable LED comes on to show a FIRE indication. When the FIRE indication shows, the pilot pushes the applicable L ENG FIRE, APU FIRE, or R ENG FIRE PBA to stop the engine or APU that has a fire.

FIRE EXT 1 and FIRE EXT 2

The pilot uses the applicable FIRE EXT 1 or FIRE EXT 2 PBA to extinguish fire in the engine or APU. These PBAs are momentary-type switches with guards and LEDs. The LED comes on to show the ARMED indication when the pilot pushes the applicable PBA. The ARMED indication tells the pilot that the applicable fire bottle is ready for discharge. To extinguish a fire in the L or R engine, the pilot pushes and holds the applicable FIRE EXT 1 or FIRE EXT 2 PBA to discharge the related fire bottle 1 or fire bottle 2. To extinguish a fire in the APU, the pilot pushes and holds the FIRE EXT 2 PBA (only the fire bottle 2 can be used to extinguish a fire in the APU).

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The switching control system interfaces with the following systems/components:

• Engine Fire Detection System 
• APU Fire Detection System 
• Fire Extinguishing System 
• Engine Condition - Fault Reporting (EC-FR) System 
• Ignition System
• Full Authority Digital Engine Control (FADEC) System 
• Engine Starting System 

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Component Location Index
IDENT	DESCRIPTION	LOCATION	IPC REF
PL15	ENGINE CONTROL PANEL	ZONE(S) 212	74-30-01

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