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CH-47D Electrical System. ACTION: Analyze electrical system malfunctions and prescribe corrective actions. CONDITION: While serving as a Maintenance Test Pilot (MTP) or Flight Engineer. STANDARD: In Accordance With (IAW)
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ACTION: Analyze electrical system malfunctions and prescribe corrective actions. CONDITION: While serving as a Maintenance Test Pilot (MTP) or Flight Engineer. STANDARD: In Accordance With (IAW) TM 55-1520-240-Series. CH-47D Electrical System Terminal Learning Objective
Safety Requirements: None. Risk Assessment Level: Low. Environmental Considerations: None. Evaluation: Written examination. CH-47D Electrical System Administrative Notes
CH-47D Electrical System Introduction Electricity is a fundamental force found everywhere in nature and has become one of the most powerful tools put to use by mankind.
CH-47D Electrical System Overview • For the next 4 hours, we will be discussing: • The CH-47D AC and DC electrical systems, how they function, some basic components. • There are 16 Enabling Learning Objectives (ELO).
CH-47D Electrical System ELO A ACTION: Student read ahead assignment: Identify the basic properties of electricity. CONDITION: Given a student handout. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System Questions ?
CH-47D Electrical System ELO B ACTION: Student read ahead assignment: List the six common ways to produce electricity. CONDITION: Given a student handout. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System Questions ?
CH-47D Electrical System ELO C ACTION: Identify the electrical symbols used in CH-47D troubleshooting manual schematics. CONDITION: Given a student handout and TM 55-1520-240-T-1 and 2. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System Notes Pay attention to the notes shown on the electrical schematics in the T-Manuals.
CH-47D Electrical System Schematics • Standardized and universally accepted methods used to diagram the flow of electricity from one component to the next.
CH-47D Electrical System Schematics Each Component has a unique: • Symbol • Part number • Label
CH-47D Electrical System Schematics
CH-47D Electrical System Schematics Linking components together: • Wires • Terminal Boards • Diodes • Ground Points
CH-47D Electrical System Schematics Wires: • Have a unique number assigned. • Either ink stamped or labeled.
CH-47D Electrical System Schematics Terminal Boards: • Provide for the connection of one wire or component to another. • Are located throughout the airframe.
CH-47D Electrical System Schematics Diodes: • Are one-way streets for electricity. • Most visible in the CH-47D connected to relays.
CH-47D Electrical System Schematics Ground Points: • Allow a common return path for the flow of electricity. • Used for either AC or DC.
CH-47D Electrical System Schematics
CH-47D Electrical System Schematics Linking components together: • Switches • Relays
CH-47D Electrical System Schematics Switches: • Turns on or off the flow of electricity. • Used for either AC or DC.
CH-47D Electrical System Schematics Relays: • Nothing more than remotely controlled switches. • Often used to switch components or circuits with high power requirements. • Can be used to set up a “logic flow”.
CH-47D Electrical System Schematics Battery Switch (161S1) and Battery Relay (161K1).
CH-47D Electrical System Schematics
CH-47D Electrical System Schematics Questions ?
CH-47D Electrical System Schematics Press-To-Test Annunciator Lights.
CH-47D Electrical System Schematics Transformers.
CH-47D Electrical System ELO D ACTION: Identify the physical location of components listed on the CH-47D troubleshooting manual schematics. CONDITION: Given a student handout and TM 55-1520-240-T-2. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System Locating Components Simple Methodology • Using the schematic, start with components unique number. • Use the T-Manual to see what the component looks like. • Look up the number in the T-Manual to find the physical location. • Find the component on the airframe.
CH-47D Electrical System Locating Components Questions ?
CH-47D Electrical System ELO E ACTION: Chart the flow of current through an electrical schematic. CONDITION: Given a student handout and TM 55-1520-240-T-2. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System Electron Flow When tracing electrical flow on a schematic, start at the source of power and go towards ground.
CH-47D Electrical System Electron Flow “Ground” • A a point that, if voltage was measured, the reading would be zero volts (DC circuit). • A common connection related to all other components in a circuit (AC or DC).
CH-47D Electrical System Electron Flow “De-Energized” • Note that most schematics are drawn with the power turned off. • When troubleshooting, the mechanic must mentally turn on the circuit and trace the flow. Note: Using a High-Lighter often helps the beginner.
CH-47D Electrical System Electron Flow Battery plugged in, but not turned on.
CH-47D Electrical System Electron Flow Battery plugged in, and turned on.
CH-47D Electrical System Electron Flow Questions ?
CH-47D Electrical System Electron Flow Practical Exercise
CH-47D Electrical System Electron Flow Searchlight switch turned on, closing relay.
CH-47D Electrical System Electron Flow Searchlight light bulb on.
CH-47D Electrical System Electron Flow Searchlight extending, an example of “Logic”.
CH-47D Electrical System ELO F ACTION: List the sources of AC electrical power for the CH-47D. CONDITION: Given a student handout and TM 55-1520-240-Series. STANDARD: IAW TM 55-1520-240-Series.
CH-47D Electrical System AC Power Sources 3 Sources of AC Power • External Power. • Auxiliary Power Unit (APU) Generator. • Main Generator.
CH-47D Electrical System AC Power Sources External Power • Lowest priority of power. • If the APU or a Main Generator is turned on, External Power will be disconnected. • “EXT PWR” Caution Light usually illuminated.
CH-47D Electrical System AC Power Sources External Power • Usually supplied via AGPU, a GPU, or special hangar power supply. • Most commonly used as a source of power during post-phase or post-modification work order (MWO) power-on checks.
CH-47D Electrical System AC Power Sources APU • Second highest priority of power. • As the APU generator comes on, External Power goes off. • The APU Generator will disconnect if a Main Generator comes on-line.
CH-47D Electrical System AC Power Sources The APU is most commonly used for: • Start-up and shut-down of the helicopter. • Ground check-out and troubleshooting of systems. • During an in-flight emergency (dual generator failure).
CH-47D Electrical System AC Power Sources Main Generators • Highest priority of power. • Turning on a Main Generator will disconnect the APU Generator or External AC Power. • Usable when the Rotor RPM is greater than 86%.
CH-47D Electrical System ELO G ACTION: List the major components of the main AC generating system. CONDITION: Given a student handout and TM 55-1520-240-Series. STANDARD: IAW TM 55-1520-240-Series.