Monday, November 19, 2007


The Limitations section contains only those limitations required by regulation or that are necessary for the safe operation of the airplane, powerplant, systems, and equipment. It includes operating limitations, instrument markings, color-coding, and basic placards. Some of the limitation areas are: airspeed, powerplant, weight and loading distribution, and flight.

Airspeed limitations are shown on the airspeed indicator by color-coding and on placards or graphs in the airplane.

A red line on the airspeed indicator shows the airspeed limit beyond which structural damage could occur. This is called the never-exceed speed (VNE). A yellow arc indicates the speed range between maximum structural cruising speed (VNO) and VNE.

Operation of the airplane in the yellow airspeed arc is for smooth air only, and then with caution. A green arc depicts the normal operating speed range, with the upper end at VNO, and the lower end at stalling speed at maximum weight with the landing gear and flaps retracted (VS1). The white arc depicts the flap operating range, with the upper end at the maximum flap extended speed (VFE), and the lower end at the stalling speed with the landing gear and flaps in the landing configuration (VSO).

In addition to the markings listed above, small multiengine airplanes will have a red radial line to indicate single-engine minimum controllable airspeed (VMC). A blue radial line is used to indicate single-engine best rate-of-climb speed at maximum weight at sea level (VYSE).

The Powerplant Limitations area describes operating limitations on the airplane's reciprocating or turbine engine(s). These include limitations for takeoff power, maximum continuous power, and maximum normal operating power, which is the maximum power the engine can produce without any restrictions, and is depicted by a green arc. Other items that can be included in this area are the minimum and maximum oil and fuel pressures, oil and fuel grades, and propeller operating limits.

All reciprocating engine powered airplanes must have a rpm indicator for each engine. Airplanes equipped with a constant-speed propeller use a manifold pressure gauge to monitor power output and a rpm gauge to monitor propeller speed. Both instruments depict the maximum operating limit with a red radial line and the normal operating range with a green arc. Some instruments may have a yellow arc to indicate a caution area.

The Weight and Loading Distribution area contains the maximum certificate weights, as well as the center-of-gravity (CG) range. The location of the reference datum used in balance computations is included in this section. Weight and balance computations are not provided in this area, but rather in the Weight and Balance section of the AFM/POH.

This area lists authorized maneuvers with appropriate entry speeds, flight load factor limits, and kinds of operation limits. It also indicates those maneuvers that are prohibited, such as spins, acrobatic flight, and operational limitations such as flight into known icing conditions.

Most airplanes display one or more placards that contain information having a direct bearing on the safe operation of the airplane. These placards are located in conspicuous places within the airplane and are reproduced in the Limitations section or as directed by an Airworthiness Directive (AD).

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