ATA 74 Ignition - Bombardier DHC 8-400 (PWC PW150) PDF

BOMBARDIER DHC 8-400 (PWC PW150) ATA 74 - IGNITION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM GENERAL DESCRIPTION The ignition system gives the electrical energy to igni...

BOMBARDIER DHC 8-400 (PWC PW150) ATA 74 - IGNITION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM GENERAL DESCRIPTION The ignition system gives the electrical energy to ignite the fuel/air mixture during engine start-up. It also gives in flight re-light capability in the event of a flame out. The system functions with these components: • • • • • Ignition select switch FADEC Ignition exciters Cables Plugs The ignition system has these systems: • • • Ignition Power Supply Distribution Ignition Selection LEADING PARTICULARS The system has these specifications: Input Voltage 28V DC Spark rate at 28V DC 1.4 spark/sec Continuous Operation 3000 hours Output Voltage 15 to 20 KV TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 2 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM GENERAL DESCRIPTION CONTINUED The PW150A ignition system has the ignition exciter, the FADEC, the ignition cables and the ignition plugs. The ignition exciter is a dual channel unit in a single housing. It is supplied with aircraft 28V DC through a single electrical connector for both channels. It outputs high voltage to the igniter plugs when selected ON. The ignition exciter is connected to the igniter plugs by a pair of braided cables. The cables are mounted with quick release connectors to facilitate removal and installation. The igniter plugs are located in the gas generator case. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 3 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM SYSTEM OPERATION The distribution system has of the ignition cables and the ignition plugs. The ignition cables transmit the high voltage electrical energy from the ignition exciter to the ignition plugs. They are located on the right side of the engine and secured by quick release clamps. The ignition plugs use the high voltage power to create sparks to ignite the fuel/air mixture. They are located on the gas generator case at the 4 and 7 o’clock positions. To facilitate removal and installation the plugs are the drop in type. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 4 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITION SYSTEM BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 5 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM SYSTEM OPERATION COMPONENT LOCATION AND DESCRIPTION IGNITION POWER SUPPLY (IGNITION EXCITER) The ignition exciter receives 28V DC from the aircraft bus. It increases this voltage to a high enough level to cause the ignition plugs to spark. The ignition exciter is flexibly mounted on the right side of the engine. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 6 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITION EXCITER LOCATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 7 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM SYSTEM OPERATION CONTROLS AND INDICATIONS IGNITION SELECTION When START is selected, the FADEC commands only one of the igniters to operate. On subsequent starts the other igniter is used. This is done to minimize ignitor wear. During flame out, or when the engine is experiencing surging, the FADEC commands both ignitors to operate continuously. The FADEC logic for the start system is: • • • Ignitors used alternately for ground starts If no light off is detected by FADEC after 8 seconds from selection of fuel ON, both ignitors are selected on and a fault count is started If five fault counts are logged for an ignitor, the FADEC logs a fault code TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 8 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - ENGINE START PANEL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 9 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM INTERFACES The ignition system interfaces with these components: • • Engine Control Interface Unit (ECIU) Full Authority Digital Electronic Control (FADEC) TRAINING INFORMATION POINTS The ignition plugs are the drop in type. Be careful when you disconnect the ignition cables and attaching hardware because the plugs can fall out. The ignition plugs are fragile. You must be careful when you remove them from the engine and during handling. If you drop a plug you must replace it with a new one because it may be damaged internally. WARNING: HIGH ENERGY IN THE IGNITION SYSTEM CAN BE FATAL. OBSERVE ALL SAFETY PRECAUTIONS IN THE AMM CHAPTER 74 BEFORE WORKING ON THE SYSTEM. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 10 of 28 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 11 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION POWER SUPPLY GENERAL DESCRIPTION The ignition power supply gives the energy to the ignition plugs to create the spark that will ignite the fuel/air mixture. The ignition exciter is the ignition power supply. SYSTEM OPERATION The dual channel ignition system is powered electrically by the aircraft essential buses and energized by the FADEC. Both ignitors can be commanded by each FADEC channel, while maintaining electrical isolation between the FADEC channels and the aircraft essential buses. Only one of the two ignitors is turned on during a normal start. This is to identify any failures in the dual channel ignition system by cycling between ignitors used on subsequent ground starts. When power is supplied to the ignition exciter, the energy level is increased to a high enough level to cause the ignition plugs to spark. These sparks are used to ignite the fuel/air mixture. The ignition exciter is a sealed unit and must be returned to an overhaul facility for repair. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 12 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITION POWER SUPPLY BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 13 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM The two Igniter Plugs are located in the Gas Generator Case and are connected to the Ignition Exciter Box. They provide sparks for igniting the fuel/air mixture. IGNITION POWER SUPPLY SYSTEM OPERATION COMPONENT LOCATION AND DESCRIPTION IGNITION EXCITER The ignition exciter transforms a DC voltage input into a pulsed high voltage output. This pulsed output causes the ignitor plugs to create the sparks that will ignite the fuel/air mixture. The Ignition Exciter Box is a dual channel unit contained in a single enclosure. The Ignition Exciter Box is supplied with aircraft 28V DC through a single electrical connector for both channels. It outputs a high-tension signal to the igniter plugs when selected ON by the FADEC. The Ignition Exciter Box is connected to the Igniter Plugs by a pair of braided cables. Each channel of the FADEC can fire either or both the ignition plugs. The ignition exciter is a sealed unit that contains electronic circuitry that gives a high voltage output (15 to 20 kVA). The output is transmitted by the ignition cables to the ignitor plugs. This high voltage output causes the ignition plugs to spark at a rate of 1 to 1.4 sparks per second. When the unit is energized, a capacitor on the high voltage side of the output transformer is progressively charged. When sufficient energy to ionize a spark gap in the unit is accumulated, the capacitor discharges through a dividing and step-up transformer network across the two ignition plugs. The unit will continue functioning if one of the plugs is open or shorted, in order to operate the remaining plug. If both ignition plugs fail, or if the input voltage is switched off, the capacitor automatically discharges. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 14 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITION POWER SUPPLY DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 15 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION POWER SUPPLY SYSTEM OPERATION IGNITION FUNCTIONAL TEST In order to verify that the Ignition system is functional, the FADEC does an Ignition Test Function when in Maintenance Mode. Maintenance Mode is selected by the maintenance discrete switch on the maintenance panel. With the FADEC in Maintenance Mode and the Ignition Selection on the Engine Start Panel in the Normal position, set the PLA to FI detent and the CLA in the Shutdown position. Push the MCL switch on the Engine Control Panel to cause the FADEC to fire the Ignitors. By disabling the power supply to ignition exciter box through flight compartment circuit breakers each ignitor can be tested individually. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 16 of 28 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 17 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION DISTRIBUTION GENERAL DESCRIPTION The ignition distribution system transmits the DC pulsed high voltage output from the ignition exciter to the ignition plugs. The ignition cables transmit the high voltage signal from the ignition exciter to the ignition plugs. The ignition plugs convert the high voltage signal to high temperature sparks to ignite the fuel/air mixture. The distribution system has these components: • • Ignition Cables Ignition Plugs COMPONENT LOCATION AND DESCRIPTION IGNITION CABLES The ignition cables carry the high voltage from the ignition exciter to the ignitor plugs. The cables are mounted on the right side of the engine. The cables are flexible and provide for a shielded electrical connection between the ignition exciter and the ignition plug. Each cable is constructed from a 5 mm silicon jacketed conductor wire enclosed by an inner braid of nickel-clad copper wire. This is further enclosed by an inner core braided with nickel wire. The end fittings are stainless steel and the inner core of the cable is hermetically sealed. This is to provide protection against electromagnetic interference. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 18 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITION DISTRIBUTION CABLES TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 19 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION DISTRIBUTION COMPONENT LOCATION AND DESCRIPTION IGNITION PLUGS The ignitor plugs convert the high voltage into a spark to ignite the fuel/air mixture in the combustor. There are two ignition plugs per engine. They are installed in the gas generator case at the 4 and 7 o’clock positions. The plugs are of the drop-in type. They are secured to the engine by installing them between the gas generator case and the ignition cable fittings. This reduces the time required to replace the plugs. Each plug has a central electrode within a shell which acts as the ground. As the energy potential increases, a small current passes across the semi-conducting material until the air between the electrode and the shell ionizes. At this point, high energy voltage discharges across the gap creating a spark. The spark always occurs between the electrode and the shell. The plug shells are made from Hastelloy X for creep and fret resistance. The electrodes are made from Iridium for maximum life. Holes in the igniter body let P3 cooling air pass to the igniter tip. This cooling air helps to keep the igniter tip cool. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 20 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - IGNITORS LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 21 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION DISTRIBUTION TRAINING INFORMATION POINTS The ignition plugs are fragile. If they are dropped during handling they must be replaced with new ones. This is because damage to the interior of the plug cannot be seen from the outside. The ignition cable fittings are coated at installation to ensure good electrical conductivity. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 22 of 28 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 23 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION SELECTION GENERAL DESCRIPTION The ignition selection system transmits engine START commands to the FADEC. The system is also sets the ignition system mode to NORMAL or OFF. The ignition selection system is controlled by the ignition selection switches. They are located on a panel mounted in the flight compartment. This panel is labelled ENGINE START and has these switches: • • • Ignition Selection Switches Engine Starter Select Switch Engine Start Switch Switches on the panel select which engine is started and the ignition system operating mode. The ignition selection system operates in two modes: • • OFF NORMAL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 24 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - ENGINE START PANEL LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 25 of 28 BOMBARDIER DHC 8-400 (PWC PW150) IGNITION SYSTEM IGNITION SELECTION GENERAL DESCRIPTION CONTINUED IGNITION SELECTION SWITCHES The ignition selection switches select the ignition mode. There are two ignition modes; NORMAL and OFF. When the switches are in the NORMAL position, the FADEC activates ignition during engine starts on the ground or in-flight. When the switches are in the OFF position, the FADEC disables ignition regardless of the ground or flight status. The FADEC can command both igniters to operate during flameout or for surge accommodation. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 26 of 28 BOMBARDIER DHC 8-400 (PWC PW150) ENGINE IGNITION - ENGINE START PANEL DETAIL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 27 of 28 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 74 - IGNITION Issue 6 - January 2023 Page 28 of 28