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Aircraft Structure

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 With the release of the electronic flight display (EFD) system, conventional instruments have been replaced by multiple liquid crystal display (LCD) screens.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 de-clutter 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]

Figure 2-18. Analog display (top) and digital display (bottom) from a Cessna 172.

Figure 2-18. Analog display (top) and digital display (bottom) from a Cessna 172.

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.

Whether an aircraft has analog or digital (“glass”) instruments, the instrumentation falls into three different categories: performance, control, and navigation.

Performance Instruments

The performance instruments indicate the aircraft’s actual performance. Performance is determined by reference to the altimeter, airspeed or vertical speed indicator (VSI), heading indicator, and turn-and-slip indicator. The performance instruments directly reflect the performance the aircraft is achieving. The speed of the aircraft can be referenced on the airspeed indicator. The altitude can be referenced on the altimeter. The aircraft’s climb performance can be determined by referencing the VSI. Other performance instruments available are the heading indicator, angle of attack indicator, and the slip-skid indicator. [Figure 2-19]

Figure 2-19. Performance instruments.

-Click to Enlarge- Figure 2-19. Performance instruments.

Control Instruments

The control instruments [Figure 2-20] display immediate attitude and power changes, and are calibrated to permit adjustments in precise increments. The instrument for attitude display is the attitude indicator. The control instruments do not indicate aircraft speed or altitude. In order to determine these variable and others, a pilot must reference the performance instruments.

Figure 2-20. Control instruments.

-Click to Enlarge- Figure 2-20. Control instruments.

Navigation Instruments

The navigation instruments indicate the position of the aircraft in relation to a selected navigation facility or fix. This group of instruments includes various types of course indicators, range indicators, glideslope indicators, and bearing pointers. Newer aircraft with more technologically advanced instrumentation provide blended information, giving the pilot more accurate positional information.

Navigation instruments are comprised of indicators that display GPS, very high frequency (VHF) omni-directional radio range (VOR), nondirectional beacon (NDB), and instrument landing system (ILS) information. The instruments indicate the position of the aircraft relative to a selected navigation facility or fix. They also provide pilotage information so the aircraft can be maneuvered to keep it on a predetermined path. The pilotage information can be in either two or three dimensions relative to the ground-based or space-based navigation information. [Figures 2-21 and 2-22]

Figure 2-21. A comparison of navigation information as depicted on both analog and digital displays.

-Click to Enlarge- Figure 2-21. A comparison of navigation information as depicted on both analog and digital displays.

Figure 2-22. Analog and digital indications for glideslope interception.

-Click to Enlarge- Figure 2-22. Analog and digital indications for glideslope interception.


Composite Construction (Part Four) – Disadvantages of Composites

Composite construction comes with its own set of disadvantages, the most important of which is the lack of visual proof of damage. Composites respond differently from other structural materials to impact, and there is often no obvious sign of damage. For example, if a car backs into an aluminum fuselage, it might dent the fuselage. […]

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Composite construction offers several advantages over metal, wood, or fabric, with its lighter weight being the most frequently cited. Lighter weight is not always automatic. It must be remembered that building an aircraft structure out of composites does not guarantee it will be lighter, it depends on the structure, as well as the type of […]

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Composite Construction (Part Two) – Composite Materials in Aircraft

Composite materials are fiber-reinforced matrix systems. The matrix is the “glue” used to hold the fibers together and, when cured, gives the part its shape, but the fibers carry most of the load. There are many different types of fibers and matrix systems. In aircraft, the most common matrix is epoxy resin, which is a […]

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Composite Construction (Part One) – History

The use of composites in aircraft construction can be dated to World War II aircraft when soft fiberglass insulation was used in B-29 fuselages. By the late 1950s, European high performance sailplane manufacturers were using fiberglass as primary structures. In 1965, the FAA type certified the first all-fiberglass aircraft in the normal category, a Swiss […]

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Types of Aircraft Construction – Truss Structure

The main drawback of truss structure is its lack of a streamlined shape. In this construction method, lengths of tubing, called longerons, are welded in place to form a well-braced framework. Vertical and horizontal struts are welded to the longerons and give the structure a square or rectangular shape when viewed from the end. Additional […]

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Aircraft Subcomponents

The subcomponents of an airplane include the airframe, electrical system, flight controls, and brakes. The airframe is the basic structure of an aircraft and is designed to withstand all aerodynamic forces, as well as the stresses imposed by the weight of the fuel, crew, and payload. The primary function of an aircraft electrical system is […]

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Major Components (Part Four) The Powerplant

The powerplant usually includes both the engine and the propeller. The primary function of the engine is to provide the power to turn the propeller. It also generates electrical power, provides a vacuum source for some flight instruments, and in most single-engine airplanes, provides a source of heat for the pilot and passengers. [Figure 2-13] […]

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Major Components (Part Three) Landing Gear

The landing gear is the principal support of the airplane when parked, taxiing, taking off, or landing. The most common type of landing gear consists of wheels, but airplanes can also be equipped with floats for water operations, or skis for landing on snow. [Figure 2-12] The landing gear consists of three wheels—two main wheels […]

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