Light Sport Aircraft Airframe and Systems

Construction

LSAs may be constructed using wood, tube and fabric, metal, composite, or any combination of materials. In general, a primary effort by the manufacturer is to keep the airplane lightweight while maintaining the structural requirements. Composite LSAs tend to be sleek and modern looking with clean lines as molding of the various components allows designers great flexibility shaping the airframe. Other LSAs are authentic-looking renditions of early aviation airplanes with fabric covering a framework of steel tubes. Of course, LSAs may be anything in between using both metal and composite construction. [Figure 16-3]

Figure 16-3. LSA can be constructed using both metal and composites.

Figure 16-3. LSA can be constructed using both metal and composites.

 

A pilot transitioning into LSA should understand the type of construction and what are typical concerns for each type of construction:

  • Steel tube and fabric—while the techniques of steel tube and fabric construction hails back to the early days of aviation, this construction method has proven to be lightweight, strong, and inexpensive to build and maintain. Advances in fabric technology continue to make this method of covering airframes an excellent choice. Fabric can be limited in its life span if not properly maintained. Fabric should be free from tears, well-painted with little to no fading, and should easily spring back when lightly pressed.
  • Aluminum—an aluminum-fabricated airplane has been a favorite choice for decades. Pilots should be quite familiar with this type of construction. Generally, airframes tend to be lightly rounded structures dotted with rivets and fasteners. This construction is easily inspected due to the wide-spread experience with aluminum structures. Conditions such as corrosion, working rivets, dents, and cracks should be a part of a pilot’s preflight inspection.
  • Composite—a composite airplane is principally made from structural epoxies and cloth-like fabrics, such as bi-directional and uni-directional fiberglass cloths, and specialty cloths like carbon fiber. Airframe components, such as wing and fuselage halves, are made in molds that result in a sculpted, mirror-like finish. Generally, composite construction has few fasteners, such as protruding rivets and bolts. Pilots should become acquainted with inspection concerns such as looking for hair-line cracks and delaminations.

Engines

LSAs use a variety of engines that range from FAA-certificated to non-FAA-certificated. Engine technology varies significantly from conventional air-cooled to high revolutions per minute (rpm)/water-cooled designs. [Figure 16-4] These different technologies present a transitioning pilot new training opportunities and challenges. Since most LSAs use non-FAA-certificated engines, a transitioning pilot should fully understand the engine controls, procedures, and limitations. In most LSA airplanes, engines are water-cooled, 4-cycle, carbureted with a gear reduction drive. Engines such as these have much higher operating rpms and require a gear-box to reduce the propeller rpms to the proper range. Because of the higher operating rpms, vibration and noise signatures are quite different in most LSAs when compared to most standard type certificated designs.

Figure 16-4. A water-cooled 4-cycle engine.

Figure 16-4. A water-cooled 4-cycle engine.

 

Instrumentation

In addition to advanced airframe and engine technology, LSAs often have advanced flight and engine instrumentation. Often installed are electronic flight instrumentation systems (EFIS) that provide attitude, airspeed, altimeter, vertical speed, direction, moving map, navigation, terrain awareness, traffic, weather, engine data, etc., all on one or two liquid crystal displays. [Figure 16-5] EFIS has become a cost-effective replacement for traditional mechanical gyros and instruments. Compared to mechanical instrumentation systems, EFIS requires almost no maintenance. There are tremendous advantages to EFIS systems as long as the pilot is correctly trained in its use. EFIS systems can cause a “heads down” syndrome and loss of situation awareness if the pilot is not trained to quickly and properly configure, access, program, and interpret the information provided. Transition training must include, if EFIS is installed, instruction in the use of the specific EFIS installed in the training airplane. In some cases, EFIS manufacturers or third party products are available for the pilot to practice EFIS operations on a personal computer as opposed to learning their functions in flight.

Figure 16-5. An electronic flight instrumentation system provides attitude, airspeed, altimeter, vertical speed, direction, moving map, navigation, terrain awareness, traffic, weather, and engine data all on one or two liquid crystal displays.

Figure 16-5. An electronic flight instrumentation system provides attitude, airspeed, altimeter, vertical speed, direction, moving map, navigation, terrain awareness, traffic, weather, and engine data all on one or two liquid crystal displays.