Ignition Reviewer Finals PDF

3 electrical generators (2 of the generators are engine driven and one is APU driven) APU makes the airplane self-sufficient by providing on ground electrical power AUTOMATIC BUS TRANSFER SYSTEM -- this system increases electrical power reliability Onboard power system annunciator & Test modules...

3 electrical generators (2 of the generators are engine driven and one is APU driven) APU makes the airplane self-sufficient by providing on ground electrical power AUTOMATIC BUS TRANSFER SYSTEM -- this system increases electrical power reliability Onboard power system annunciator & Test modules -- ease electrical malfunction Electrical power system operates in the following manner - Constant speed drive (CSD) and generator are driven by each engine to provide 115 volts, 400Hz, three-phase AC power. Each CSD can supply 50 KVA - Variable speed constant frequency (VSCF) generator will also supply 50 KVA - Transformer/Rectifier units provide 28v DC power by converting 115V AC to 28V DC - APU generator can supply 60 KVA for ground operation and 50 KVA for flight operation APU GENERATOR BUS SWITCHES - On -- connects APU generator to no. 1 or 2 generator bus - OFF -- disconnects APU generator from no. 1 or 2 generator bus - APU can power both generator buses on the ground and only one can be powered in the air GENERATOR AC AMMETER -- displays engine generator no.1 or 2 load in amperes GROUND POWER SWITCH - ON -- if ground power is available, the engine or APU generator are tripped off generator buses - OFF -- ground power tripped off generator buses BUS TRANSFER SWITCH (Guarded in AUTO) - AUTO -- transfer bus automatically transfers to opposite generator power source - OFF -- isolates DC systems **AUXILIARY POWER UNIT (APU)** Garret 85-129 Garret 36-280 Sundstrand APS 2000 Controls and Indicator APU Generator -- is mounted on the accessory drive pad. 60KVA ground, 50KVA flight Bleed air from the APU - APU supplies bleed air for air-conditioning and engine start - Using APU bleed air for air conditioning during takeoff improves takeoff performance APU Starting - The APU is started by the airplane battery or by external DC power Automatic shutdown Feature - Shuts down the APU or overspeed, high oil temperature, low oil pressure or fire Exhaust noise heard by passengers is minimized through 2 factors: 1. Use of an acoustically treated air inlet and exhaust duct 2. Its distance from the cabin and ground service points APU is readily accessible for inspection, maintenance, or removal through a large door in the fuselage directly below it. GARRET 85-129 - 2 stage centrifugal compressor (single combustion chamber and one radical inflow turbine) - The accessories group is at the front of the unit GARRET 36-280 - 2 centrifugal impellers and a single centrifugal turbine with a containment ring - Unit is monitored and controlled by a Full Authority Digital Electronic Control (FADEC) -- it provides built-in tests (BITE) and historical informataion SUNDSTRAND APS 2000 - Single centrifugal impeller and a single centrifugal turbine CONTROLS AND INDICATORS - Controls for the APU are located on the forward head panel and consist of the following: 1. APU SWITCH -- 3 position switch: on, off, start. There is a four-position option for a 60-second cooldown (Garret 85-129 only) MAINTENANCE LIGHT 1. Garret 85-129 -- illuminated blue when oil tank fluid level is low 2. Sundstrand APS 2000 and Garret 36-280 - Maintenance light is an indication of a non-critical failure - FADEC will display an alpha-numeric code that identifies a more specific description of the problem 3. Low oil pressure light -- illuminated amber when oil pressure is low. APU automatically shuts down FAULT LIGHT 1. Garret 85-129 -- illuminated amber when oil temperature exceeds maximum allowable 2. Sundstrand APS 2000 and Garret 36-280 - Fault line is an indication of critical failure 3. Overspeed light -- illuminated amber when APU turbine speed exceeds allowable rpm AC AMMETER - Displays APU generator load current EXHAUST GAS TEMPERATURE INDICATOR - Displays APU exhaust gas temperature in c APU FIRE PROTECTION - APU is located within a fire protection shroud - Fault in the detection system causes the APU DET INOP light on the fire control panel and the master caution lights (OVHT/DET) on the glareshield to illuminate Controls on the APU fire protection panel P28: 1. APU fire warning light -- illuminated red light indicates a fire in the APU 2. APU fire warning horn -- indicates fire in the APU when activated 3. APU horn cutout switch -- silences the fire bell 4. APU fire control handle -- when pulled, this handle arms the APU bottle discharge switch 5. APU bottle discharge switch -- APU fire extinguisher discharges when the switch is actuated PNEUMATICS - Used to supply pressurized air for engine starting The air source for engine starting is obtained from the on-board auxiliary power unit (APU) or an external ground cart The normal in-flight cabin air-source is from the 5^th^ stage of the compressor section At low-engine, 9^th^ stage air automatically substitutes Precooler -- limits the temperature of the air by using fan-stage air APU may be used to supply air to the air-conditioning system in the flight, allowing maximum thrust APU may also be used for single pack air-conditioning operation up to 17,000ft altitude