Investigation Into Electrical & Instrumentation Systems

Assignment Brief

In this paper, you are supposed to write a report on the topic of ‘An investigation into electrical & instrumentation systems as used on aircraft’ which encompasses the selection ofan aircraft, either military or civil, together with investigating its electrical system. Moreover, complete with architecture, voltages, currents, components, distribution and as much detail as you can explore. Likewise, explain in detail certain aspects as well such as demonstrating how the electrical generation system satisfies either FAA, CAA, or JAR safety requirements, etc.

Instructions 

ENG 491 Coursework Brief

An investigation into the Electrical and Instrumentation Systems used on Aircraft.

This coursework is made up of:

An investigation into Electrical & Instrumentation Systems as used on Aircraft - 100% of overall mark.

You should choose an aircraft, either military or civil, and investigate its electrical system, complete with architecture, voltages, currents, components, distribution and as much detail as you can find. Show how the electrical generation system satisfies either FAA, CAA, or JAR safety requirements, and how the system has been designed to incorporate redundancy, and how this provides safe and uninterrupted power in all flight cases. You should also detail the Instrumentation System found on your aircraft, how the information in displayed to the pilot/s and where and how this information is generated.

Marks breakdown:

• 15 marks for introduction
• 35 marks for Electrical Generation & Distribution
• 15 marks for Safety Requirements
• 35 marks for Instrumentation System

This report should be at least 1000 words, diagrams and drawings are permissible, all references must be recorded using IEEE referencing

Sample Answer

An Investigation into the Electrical and Instrumentation Systems Used on the Boeing 787 Dreamliner

Introduction

The Boeing 787 Dreamliner is a revolutionary long-haul civil aircraft developed by Boeing Commercial Airplanes. Launched in 2011, it was designed with a focus on fuel efficiency, passenger comfort, and technological advancement. A key part of the aircraft’s innovation is its electrical and instrumentation systems, which have replaced many traditional pneumatic and hydraulic systems. This report explores the Dreamliner’s electrical generation and distribution system, the architecture, voltages, components, safety compliance with FAA and JAR standards, and the advanced instrumentation system used to display critical flight data.

Electrical Generation & Distribution System 

The Boeing 787 is known for its "More Electric Aircraft" architecture. Instead of using bleed air for environmental and engine start systems (as seen in previous aircraft), the 787 relies heavily on electrical systems. It generates about 1 megawatt of power, nearly twice as much as older aircraft like the Boeing 777.

System Architecture

The aircraft has four primary Integrated Drive Generators (IDGs), two per engine, producing 115V AC at 400Hz, and backup systems like two 28V DC batteries and an Auxiliary Power Unit (APU) generator. The electrical power system is structured around two electrical buses (left and right) which support redundant distribution to ensure continuous power supply.

Voltages and Currents

• Primary AC Power: 115V AC, 400Hz (3-phase)

• DC Power: 28V DC for avionics, battery systems

• High Voltage DC: 270V DC for heavy loads like environmental control systems and galley ovens

The system incorporates Power Electronics Units (PEUs) and Motor Control Electronics (MCEs) to convert AC to DC and regulate distribution to various components.

Components and Distribution

Major components include:

• Variable Frequency Generators (VFGs)

• Transformer Rectifier Units (TRUs)

• Solid-State Power Controllers (SSPCs)

• Remote Power Distribution Units (RPDUs)

The electrical power is distributed through primary and secondary buses, which feed different aircraft systems. If a generator fails, the system automatically reroutes power using auto-load shedding and cross-channel feeders, ensuring no single point of failure can disable the aircraft.

Safety Requirements

The 787`s electrical system complies with FAA (Federal Aviation Administration) and JAR (Joint Aviation Requirements) safety standards. Key safety features include:

Redundancy

• Dual generators on each engine

• Multiple backup batteries and APU generator

• Independent power channels for flight-critical systems

Lightning & Surge Protection

All wiring is shielded and routed to avoid electromagnetic interference. Surge arrestors are installed to protect from lightning strikes.

Fire Protection & Isolation

Automatic detection and circuit isolation prevent electrical fires. Faulty components are shut down immediately, and load shedding ensures the essential systems remain powered.

FAA Certification Compliance

• 14 CFR Part 25 – Airworthiness Standards

• All electrical systems undergo Electromagnetic Compatibility (EMC) and High Intensity Radiated Field (HIRF) testing

• Systems are rated under DO-160 environmental conditions testing

These measures ensure continuous, reliable, and safe power delivery under all operational conditions, from take-off to emergency descent.

Instrumentation System 

The Boeing 787 uses an advanced Electronic Flight Instrument System (EFIS), part of the Integrated Modular Avionics (IMA) framework.

Display Units

• Five 15.1-inch LCD displays in the flight deck

• Configurable screens show Primary Flight Display (PFD), Navigation Display (ND), Engine Indication and Crew Alerting System (EICAS), and system synoptics

• Backup instruments for airspeed, altitude, and attitude are provided in case of main display failure

Data Sources

Data is collected from:

• Air Data Inertial Reference Units (ADIRUs)

• Flight Control Computers (FCCs)

• Angle of Attack Sensors

• Pitot Tubes and Static Ports

• GPS and Inertial Navigation Systems

These data points feed into a central processing unit, which distributes them to relevant display panels using ARINC 429/664 communication protocols.

Pilot Interface

The 787 introduces dual Head-Up Displays (HUDs), showing critical data like airspeed, altitude, and attitude directly in the pilot’s forward view. This improves situational awareness and safety.

Alerting System

The EICAS warns the crew of system failures, abnormal operations, or maintenance needs. It provides step-by-step checklists on the displays, reducing human error.

Continued...