Aviation Maintenance Terms beginning with P

Pitch

The theoretical distance that the propeller blade reference station would move forward if it were moving along a helix with an angle equal to the blade section angle.

Pitting

Small irregularly shaped cavities from which material has been removed by erosion or corrosion. Corrosive pitting is usually accompanied by a deposit such as rust, a corrosion byproduct, formed by a corrosive agent on the base metal.

Propeller

A device for propelling an aircraft that has blades on an engine-driven shaft and that, when rotated, produces by its action on the air, a thrust approximately perpendicular to its plane of rotation. It includes associated control components normally supplied by its manufacturer.

Propeller, Constant speed

A propeller in which a governor is used to automatically provide constant revolutions per minute as the pilot selects the propeller pitch setting.

Propeller, Controllable pitch

A propeller with blades that may be altered continuously to any desired angle during flight.

Propeller, Fixed-Pitch

A one-piece propeller with fixed blade angles.

Propeller, Full feathering

A propeller with blades that can be rotated to a high positive blade angle to stop rotation (windmilling). This feature is common on multi-engine aircraft, because it allows an engine to be shut down and rotation stopped to reduce drag and asymmetric control forces.

Propeller, reversing

A propeller in which blades can be rotated to a “negative” blade angle where they will provide a rearward thrust to slow down, stop, or move the aircraft backward.