CH-47D Auxiliary Power Unit Terminal Learning Objective (TLO) Action: Describe components, operational characteristics, functions, restrictions and limitations of the CH-47D Auxiliary Power Unit (APU) Condition: In a classroom, given a student handout Standard: Correctly answer in writing, without reference, three of four questions, pertaining to Components, Operational Characteristics , Limitations, Functions, and Malfunctions of the CH- 47D APU, In Accordance With (IAW) TM 1-1520-240- 10 and the student handout Terminal Learning Objective (TLO) (Cont) Safety Requirements: None Risk Assessment: Low Environmental Consideration: None Evaluation: Each student will be evaluated on this block of instruction during the written examination. This will be a criterion type examination requiring a GO on each scored unit. You will have 90 minutes for the exam Learning Step/Activity (LSA) #1 1. Describe operational characteristics, of the Auxiliary Power Unit (APU) Components General Characteristics Model T-62T-2B Manufactured by Turbomach Consumes 90 PPH Rated Power 95 SHP Weight 74.8 W/O Generator Single stage centrifugal compressor/PT Mounted at Sta. 600 Above the ramp APU Mounting Points Mounts: Two forward and two rigid links APU to rotate down Provide: Vertical and lateral support APU System Components Motor/Pump APU Start Accumulator APU Start Module APU Overhead Generator Panel Auxiliary Power Unit APU Fuel Shutoff Valve Master APU Electronic Sequence APU Fault Caution Unit Relay Panel APU Fuel Boost Pump Solenoid Valve APU Assembly Learning Step/Activity (LSA) #2 1. Describe Principles of Operational for the APU Sections of the APU Power Turbine Assembly Reduction Drive Assembly Air Inlet, and Compressor Assembly Compressor Section Type: Single stage centrifugal-flow (impeller) Air drawn in through the inlet Combustor Assembly Provides: Intake of ambient air to the compress Protects: APU against FOD ingestion Power Turbine Section Type: Impeller turbine rotor Secured: Aft end of the turbine assembly Reduction Gear Assembly Purpose: Reduces power turbine shaft rotational speed Three mounting pad APU Start Accumulator Mounted: Sta.555 R/H Ramp Area Purpose: Stores Hydraulic Fluid APU Start Emergency Use: Utility Sub-System Indicator: 3,000 PSI APU Start Module Located: Sta.584 R/H side ramp area Directs: Signal Pressure APU Accumulator Controls: Operating Mode: APU Motor/Pump Indicator: 3,000 PSI APU Motor/Pump Mounted: Forward Portion APU Function: Motor Drives APU (Starting) Pump Supplies 3350 PSI Engine Starters Utility Sub-Systems Airframe Mounted Fuel Boost Pump Type: Rotary vane pump Supplies: 7−40 PSI to the APU driven fuel pump Energized: APU start switch RUN position Pressure Fluid Filter Type: Paper filter element Mounted: Top of the reduction drive assembly APU Fuel Control Fuel Manifold Constructed: Metal fuel line Six bosses equally spaced Start Fuel Nozzle Assembly Mounted: Combustor housing at approx. 7 O’clock position Purpose: Sprays fuel directly in front of the spark plug APU Electrical System Battery Switch Two position APU Switch Three position APU GEN switch Two position Magnetic Pickup Ignition Exciter Box Mounted: Upper R/H side of the turbine Purpose: Convert DC input to high energy AC Event/Time Meter Purpose: Tracks starts on the rotor assembly Tracks APU operational time APU Oil System Oil Sump Oil Filter Oil Pressure Switch Manual Shutoff Valve Located: Sta.540 L/H side of ramp area Purpose: Shut down the APU during an emergency Electronic Sequence Unit (ESU) Located: Sta.585 L/H side Purpose: Sequences the start procedure of the APU Continuously monitors the APU operation Contains: Four BITE latches for fault indications BITE Information New Modification (ESU) Learning Step/Activity (LSA) #3 1. Describe Start Procedures, Operational Restrictions and Emergency Procedures of the APU Start Procedures Start Procedures Three Positions Switch Off Run Start Place switch to RUN for 3-5 seconds Move switch to START for 2 seconds and release to RUN Master Caution/Advisory Panel APU Operational Restriction Tail in the wind!!! APU Exhaust The APU shall not be started with a tail wind in excess of 25 knots Pg: 9-1-22 APU Procedures EmergencyFire APU switch – OFF. ABORT START. Check On Learning What two components are driven by the APU? Motor/Pump and Generator How long should you wait before attempting a restart on the APU? 1 Minute If the APU ON caution light fails to comes ON, what should you do? Record the BITE information on 2408-13 What is the maximum tailwind for starting the APU? 25 knots Summary Have a nice day and Safe Flying!
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