Download CH-47D Electrical System Operation

CH-47D Electrical System
CH-47D Electrical System
Terminal Learning Objective
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.
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CH-47D Electrical System
Administrative Notes
Safety Requirements: None.
Risk Assessment Level: Low.
Environmental Considerations: None.
Evaluation: Written examination.
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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.
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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).
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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.
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CH-47D Electrical System
Questions ?
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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.
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CH-47D Electrical System
Questions ?
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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.
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CH-47D Electrical System
Notes
Pay attention to the notes shown on the
electrical schematics in the T-Manuals.
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CH-47D Electrical System
Schematics

Standardized and universally accepted
methods used to diagram the flow of
electricity from one component to the
next.
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CH-47D Electrical System
Schematics
Each Component has a unique:



Symbol
Part number
Label
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CH-47D Electrical System
Schematics
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CH-47D Electrical System
Schematics
Linking components together:




Wires
Terminal Boards
Diodes
Ground Points
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CH-47D Electrical System
Schematics
Wires:


Have a unique number assigned.
Either ink stamped or labeled.
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CH-47D Electrical System
Schematics
Terminal Boards:


Provide for the connection of one
wire or component to another.
Are located throughout the
airframe.
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CH-47D Electrical System
Schematics
Diodes:


Are one-way streets for electricity.
Most visible in the CH-47D connected
to relays.
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CH-47D Electrical System
Schematics
Ground Points:


Allow a common return path for the
flow of electricity.
Used for either AC or DC.
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CH-47D Electrical System
Schematics
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CH-47D Electrical System
Schematics
Linking components together:


Switches
Relays
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CH-47D Electrical System
Schematics
Switches:


Turns on or off the flow of electricity.
Used for either AC or DC.
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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”.
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CH-47D Electrical System
Schematics
Battery Switch (161S1) and Battery Relay (161K1).
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CH-47D Electrical System
Schematics
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CH-47D Electrical System
Schematics
Questions ?
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CH-47D Electrical System
Schematics
Press-To-Test Annunciator Lights.
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CH-47D Electrical System
Schematics
Transformers.
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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.
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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.

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CH-47D Electrical System
Locating Components
Questions ?
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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.
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CH-47D Electrical System
Electron Flow
When tracing electrical flow on a schematic,
start at the source of power and go towards
ground.
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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).

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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.
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CH-47D Electrical System
Electron Flow
Battery plugged in, but not turned on.
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CH-47D Electrical System
Electron Flow
Battery plugged in, and turned on.
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CH-47D Electrical System
Electron Flow
Questions ?
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CH-47D Electrical System
Electron Flow
Practical Exercise
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CH-47D Electrical System
Electron Flow
Searchlight switch turned on, closing relay.
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CH-47D Electrical System
Electron Flow
Searchlight light bulb on.
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CH-47D Electrical System
Electron Flow
Searchlight extending, an example of “Logic”.
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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.
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CH-47D Electrical System
AC Power Sources
3 Sources of AC Power

External Power.

Auxiliary Power Unit (APU) Generator.

Main Generator.
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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.
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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.
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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.
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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).
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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%.
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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.
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CH-47D Electrical System
Main AC System Components
Main Generator
OIL
INLET
PORT
PMG
SECTION
EXCITOR /
ROTATING
RECTIFIER
ASSEMBLY
MAIN ROTOR
WINDINGS
OIL OUTLET
PORT
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CH-47D Electrical System
Main AC System Components
Generator Control Unit (GCU)
 Located in the left and right
electrical compartments.
 Receives power to operate
from the PMG section of the
Main Generator.
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CH-47D Electrical System
Main AC System Components
Generator Control Unit (GCU)
Monitors operation of the generator for:
 Over-Voltage.
 Under-Voltage.
 Under-Frequency (an MTP check).
 Feeder Fault.
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CH-47D Electrical System
Main AC System Components
GCU – Feeder Fault Protection
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CH-47D Electrical System
Main AC System Components
Main Generator Contactor
 Located in the
respective PDP.
 Allows Generator to
connect to Bus.
 Relay power comes
from GCU (28 VDC).
 Permits Cross-Tie.
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CH-47D Electrical System
ELO H
ACTION: List the components of the APU AC
system.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
APU AC System Components
APU Generator

A 20 KVA, air cooled Generator mounted on the
APU.
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CH-47D Electrical System
APU AC System Components
APU Generator – 3 Sections:



A PMG section.
An Exciter section.
A main generator section (rotor and stator).
Functions similar to the Main Generator.
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CH-47D Electrical System
APU AC System Components
APU Generator Control Unit (GCU):



Located in right electrical
compartment.
Receives power from the PMG.
Requires a conversion plug.
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CH-47D Electrical System
APU AC System Components
APU (GCU) provides protection for:




Under-Voltage.
Over-Voltage.
Under-Frequency.
Feed Fault.
Functions similar to Main Generator System,
voltages are slightly different.
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CH-47D Electrical System
APU AC System Components
APU Generator Slave Relay:
APU
Generator
Slave Relay



Located in # 2 PDP.
Requires 28 VDC from
APU GCU to operate.
Provides Cross-Tie.
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CH-47D Electrical System
APU AC System Components
APU Generator Contactor:




Located in # 2 PDP.
Connects APU Generator to the Bus.
Requires 28 VDC from APU GCU
to operate.
Provides Cross-Tie.
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CH-47D Electrical System
APU AC System Components
APU Generator Contactor:
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CH-47D Electrical System
ELO I
ACTION: List the components of the External
AC Power System.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
External AC Power System Components
External Power Receptacle:


Located just forward of the left
electrical compartment.
AC power plug utilizes the
lower connector.
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CH-47D Electrical System
External AC Power System Components
External Power Monitor:


Located in the Left Electrical
Compartment.
Monitors for:
- Proper Voltage, Frequency,
and Phase Sequence.
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CH-47D Electrical System
External AC Power System Components
External Power Contactor:



Located in the # 1 PDP.
Connects External AC Power to
the Bus.
Provides AC Cross-Tie.
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CH-47D Electrical System
External AC Power System Components
External Power Contactor:
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CH-47D Electrical System
ELO J
ACTION: Analyze the application of External AC
Power to the aircraft electrical system.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
Analyze External Power Application
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CH-47D Electrical System
Analyze External Power Application
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CH-47D Electrical System
Analyze External Power Application
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CH-47D Electrical System
Analyze External Power Application
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CH-47D Electrical System
Analyze External Power Application
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CH-47D Electrical System
ELO K
ACTION: Analyze the application of the # 1
Main Generator AC Power to the
aircraft electrical system.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
Analyze #1 Generator Power Application
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CH-47D Electrical System
Analyze #1 Generator Power Application
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CH-47D Electrical System
Analyze #1 Generator Power Application
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CH-47D Electrical System
Analyze #1 Generator Power Application
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CH-47D Electrical System
Analyze #1 Generator Power Application
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CH-47D Electrical System
ELO L
ACTION: List the sources of DC power for the
CH-47D.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
DC Power Sources
3 DC Power Sources:



External DC.
Transformer-Rectifier.
Battery
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CH-47D Electrical System
DC Power Sources
External DC Power:


Highest priority of DC power.
Supplied by AGPU, GPU, or hangar
power supply.
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CH-47D Electrical System
DC Power Sources
Transformer-Rectifier (T/R):



Second highest priority of DC power.
Normally powers the Bus when a Generator
is on-line.
Will power all DC Buses except Battery Bus.
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CH-47D Electrical System
DC Power Sources
Battery:

When no other source is available, the
Battery will power –
The Battery Bus, the Switched Battery Bus,
and the Essential Bus.
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CH-47D Electrical System
ELO M
ACTION: List the components of the
Transformer-Rectifier system.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
T/R System Components


Transformer-Rectifier (T/R).
Reverse Current Cutout (RCCO).
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CH-47D Electrical System
T/R System Components
Transformer-Rectifier:



Located in the Left and Right
Electrical compartments.
Converts 115 VAC to 28 VDC
via a step-down transformer
and a rectifier (diode) circuit.
Can supply up to 200 amps.
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CH-47D Electrical System
T/R System Components
Reverse Current Cutout (RCCO):



Located in the respective PDP.
Protects the T/R from reverse
current (voltage).
Connects T/R output to the DC
Bus.
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CH-47D Electrical System
ELO N
ACTION: List the components of the battery and
charging system.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
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CH-47D Electrical System
Battery and Charging System Components



Battery Charger (NICAD only).
Battery (NICAD).
Battery (SLAB).
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CH-47D Electrical System
Battery and Charging System Components
Battery Charger (NICAD only):




Located in the Left Electrical
Compartment.
Monitors and controls the state
of charge.
Converts 115 VAC to 28 VDC
Is slowly being phased out.
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CH-47D Electrical System
Battery and Charging System Components
Battery Charger monitors Battery for:




Over-temperature.
Cell imbalance.
Open circuit.
Charger fault.
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CH-47D Electrical System
Battery and Charging System Components
Battery (NICAD):


Located in the Left
Electrical Compartment.
It is a nickel-cadmium
battery that uses
potassium hydroxide
(base) as an electrolyte.
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CH-47D Electrical System
Battery and Charging System Components
Battery (SLAB):




Newest Battery used in Army aviation.
Sealed Lead Acid Battery (SLAB)
utilizing sulfuric acid as the electrolyte.
Different design, same rating as NICAD.
Lower maintenance requirement.
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CH-47D Electrical System
ELO O
ACTION: List the components of the DC
External Power System.
CONDITION: Given a student handout and TM
55-1520-240-Series.
STANDARD: IAW TM 55-1520-240-Series.
96
CH-47D Electrical System
DC External Power System Components
External Power Receptacle:


Used to connect External
DC (or AC) power.
Located on the forward
side of the Left Electrical
Compartment.
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CH-47D Electrical System
DC External Power System Components
4 DC Relays provide a Logic circuit:



External Power Relay (161K7).
External Power Control Relay (161K9).
Both RCCO Relays (161K3 and 161K4).
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CH-47D Electrical System
DC External Power System Components
Reverse DC Polarity Protection (Blocking) Diode:


Prevents voltage with
incorrect polarity from
being applied to the
DC Bus.
Won’t allow 161K7
and 161K9 to operate.
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CH-47D Electrical System
DC External Power System Components
Practical Exercise:
Complete the final Practical Exercise
in the Student Handout at your leisure.
100
CH-47D Electrical System
Summary
&
Questions?
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