Airplane mode means a configuration with nacelles on the down stops (axis aligned horizontally) and rotor speed set to cruise revolutions per minute (RPM).
Airplane mode RPM means the lower range of rotor rotational speed in RPM defined for the airplane mode cruise flight condition.
Fixed operation points mean designated nacelle angle positions selected for airworthiness reference. These are default positions used to refer to normal nacelle positioning operation of the aircraft. The nacelle angle is controlled by a self-centering switch. When the nacelle angle is 0 degrees (airplane mode) and the pilot moves the nacelle switch upwards, the nacelles are programmed to automatically turn to the first default position (for example, 60 degrees) where they will stop. A second upward move of the switch will tilt the nacelle to the second default position (for example, 75 degrees). Above the last default position, the nacelle angle can be set to any angle up to approximately 95 degrees by moving the switch in the up or down direction. The number and position of the fixed operation points may vary on different tiltrotor configurations.
Nacelle angle is defined as the angle between the rotor shaft centerline and the longitudinal axis of the aircraft fuselage.
Tiltrotor means a class of aircraft capable of vertical take-off and landing, within the powered-lift category, with rotors mounted at or near the wing tips that vary in pitch from near vertical to near horizontal configuration relative to the wing and fuselage.
Vertical takeoff and landing (VTOL) mode means the aircraft state or configuration having the rotors orientated with the axis of rotation in a vertical manner (i.e., nacelle angle of approximately 90 degrees) for vertical takeoff and landing operations.
VCON is defined as the maximum authorized speed for any nacelle angle in VTOL/Conversion mode.
VTOL/Conversion mode is all approved nacelle positions where the design operating rotor speed is used for hover operations.
VTOL mode RPM means highest range of RPM that occur for takeoff, approach, hover, and conversion conditions.
14 C.F.R. §36.1
For FEDERAL REGISTER citations affecting § 36.1 , see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.