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Pilot's Handbook of Aeronautical Knowledge
Aircraft Structure

Instrumentation: Moving into the Future

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Lightning Strike Protection
Lightning strike protection is an important consideration in
aircraft design. When an aircraft is hit by lightning, a very
large amount of energy is delivered to the structure. Whether
flying a light general aviation (GA) airplane or a large airliner,
the basic principle of lightning strike protection is the same.
For any size aircraft, the energy from the strike must be spread
over a large surface area to lower the "amps per square inch"
to a harmless level.

If lightning strikes an aluminum airplane, the electrical
energy naturally conducts easily through the aluminum
structure. The challenge is to keep the energy out of avionics,
fuel systems, etc., until it can be safely conducted overboard.
The outer skin of the aircraft is the path of least resistance.
In a composite aircraft, fiberglass is an excellent electrical
insulator, while carbon fiber conducts electricity, but not
as easily as aluminum. Therefore, additional electrical
conductivity needs to be added to the outside layer of
composite skin. This is done typically with fine metal meshes
bonded to the skin surfaces. Aluminum and copper mesh
are the two most common types, with aluminum used on
fiberglass and copper on carbon fiber Any structural repairs
on lightning-strike protected areas must also include the mesh
as well as the underlying structure.

For composite aircraft with internal radio antennas, there
must be "windows" in the lightning strike mesh in the area
of the antenna. Internal radio antennas may be found in
fiberglass composites because fiberglass is transparent to radio
frequencies, where as carbon fiber is not.

The Future of Composites
In the decades since World War II, composites have earned
an important role in aircraft structure design. Their design
flexibility and corrosion resistance, as well as the high
strength-to-weight ratios possible, will undoubtedly continue
to lead to more innovative aircraft designs in the future.
From the Cirrus SR-20 to the Boeing 787, it is obvious that
composites have found a home in aircraft construction and
are here to stay. [Figure 2-17]

Instrumentation: Moving into the Future

Until recently, most GA aircraft were equipped with
individual instruments utilized collectively to safely operate
and maneuver the aircraft. With the release of the electronic
flight display (EFD) system, conventional instruments have
been replaced by multiple liquid crystal display (LCD)
screens. The first screen is installed in front of the left seat
pilot position and is referred to as the primary flight display
(PFD). The second screen, positioned approximately in
the center of the instrument panel, is referred to as the
multi-function display (MFD). These two screens declutter
instrument panels while increasing safety. This has
been accomplished through the utilization of solid state instruments which have a failure rate far less than those of
conventional analog instrumentation. [Figure 2-18]

Composite materials in aircraft
Figure 2-17. Composite materials in aircraft, such as Columbia 350
(top), Boeing 787 (middle), and a Coast Guard HH-65 (bottom).

With today's improvements in avionics and the introduction
of EFDs, pilots at any level of experience need an astute
knowledge of the onboard flight control systems as well as
an understanding of how automation melds with Aeronautical
Decision-Making (ADM). These subjects are covered in
detail in Chapter 17, Aeronautical Decision-Making.