ATA 74, 80 - IGNITION AND STARTING

• In case of ignition delay, the ECU will automatically operate both exciters after an automatic dry motoring sequence.

• On ground automatic start abort and automatic dry cranking in case of detected hot start, stall, failure to light, hung start and starter time exceed. Up to 4 start attempts are possible.

• Manual start:

- At 20% of N2 with MASTER LEVER “ON”: Dual Ignition and Fuel Flow.

• The action on the MAN START pushbutton after placing the MASTER LEVER to “ON”, has no effect on the start valve closure. It is only done to complete the manual procedure.

• Max EGT during start 725 degrees C.

• With “CRANK” selected, ignition is inhibited.

• 4 consecutive cycles each of 2 min duration, with a 16 sec rest between each cycle are

allowed.

• IGN failure in automatic mode:

In this failure case the ECU will automatically do 2 start attempts: If engine light-up is not obtained within 15 seconds, the FADEC automatically turns the ignition and the fuel OFF and dry cranks the engine for 30 seconds before initiating automatically a new start.

• If engine light-up is not obtained within 15 seconds, the FADEC automatically cuts ignition and fuel, dry cranks for 30 seconds, aborts the autostart.

• AUTOMATIC ENGINE START:

1) ENG mode selector set on “IGN START” (Both ECUs Energized),

2) ENG(1,2) Master Switch “ON”, on signal gets passed to EIU that converts the signal and send it to ECU,

3) ECU de-energizes FUEL HP SOV, START VALVE opens,

4) At 22% of N2 speed, fuel pressure overcomes FUEL HP SOV spring force and fuel goes to the engine

5) At 50% of N2 speed, START VALVE closes and Ignition stops, ENG SELF OPERATES

• ECU remembers which ignitors have been used last flight, automatic start changes ignitors at each start up.

• IGNITION BOXES:

- IGN 1 (Upper box) → ECU CH. A

- IGN 2 (Lower box) → ECU CH. B