Aircraft Systems

0 -30 +30 0 30 60 - 60 + 60 ALT AMPS A M P Ammeter Loadmeter Figure 7-35. Ammeter and loadmeter. BOTH Pump Figure 7-36. Basic hydraulic system. 7-33 TFEL RIGHT OFF System relief valve Selector valve Double acting cylinder noitoM for the system in the event of excessive fluid pressure in the system. Each system incorporates different components to meet the individual needs of different aircraft. Figure 7-37. The landing gear supports the airplane during the takeoff run, landing, taxiing, and when parked. A mineral-based hydraulic fluid is the most widely used type for small aircraft. This type of hydraulic fluid, a kerosene-like airplane. Landing gear employing a rear-mounted wheel is petroleum product, has good lubricating properties, as well called conventional landing gear. Airplanes with conventional as additives to inhibit foaming and prevent the formation landing gear are often referred to as tailwheel airplanes. When of corrosion. It is chemically stable, has very little viscosity the third wheel is located on the nose, it is called a nosewheel, change with temperature, and is dyed for identification. Since and the design is referred to as a tricycle gear. A steerable several types of hydraulic fluids are commonly used, an aircraft nosewheel or tailwheel permits the airplane to be controlled must be serviced with the type specified by the manufacturer. throughout all operations while on the ground. Refer to the AFM/POH or the Maintenance Manual. Tricycle Landing Gear Landing Gear The landing gear forms the principal support of an aircraft on There are three advantages to using tricycle landing gear: the surface. The most common type of landing gear consists 1. It allows more forceful application of the brakes during of wheels, but aircraft can also be equipped with floats for landings at high speeds without causing the aircraft to water operations or skis for landing on snow. [Figure 7-37] nose over. The landing gear on small aircraft consists of three wheels: 2. It permits better forward visibility for the pilot during two main wheels (one located on each side of the fuselage) takeoff, landing, and taxiing. and a third wheel positioned either at the front or rear of the 3. It tends to prevent ground looping (swerving) by providing more directional stability during ground Hydraulic fluid supply operation since the aircraft’s center of gravity (CG) is forward of the main wheels. The forward CG keeps Return fluid the airplane moving forward in a straight line rather Hydraulic pressure than ground looping. Nosewheels are either steerable or castering. Steerable nosewheels are linked to the rudders by cables or rods, while castering nosewheels are free to swivel. In both cases, the aircraft is steered using the rudder pedals. Airplanes with a castering nosewheel may require the pilot to combine the use of the rudder pedals with independent use of the brakes. Tailwheel Landing Gear Tailwheel landing gear airplanes have two main wheels attached to the airframe ahead of its CG that support most of the weight of the structure. A tailwheel at the very back of the fuselage provides a third point of support. This arrangement