While our techs do their best to speak plain English and not “rotorhead” (which is its own language) we are providing a glossary for our clients who may not spend all day every day in a propeller shop. 😅
A
AD (Airworthiness Directive)
A legally enforceable rule issued by the FAA to correct unsafe conditions in aircraft, including propellers. ADs often mandate inspections, repairs, or modifications.
A&P (Airframe and Powerplant Mechanic)
A licensed technician authorized to inspect, maintain, and repair aircraft airframes and powerplants, including propeller systems.
Aluminum Blade Propeller
A type of propeller with blades made from aluminum alloy. Common in many GA and turboprop aircraft for durability and performance.
B
Blade Track
The path each propeller blade follows during rotation. Accurate blade tracking ensures balance and reduces vibration.
Blade Angle
The angle between the blade chord line and the plane of rotation. It determines the thrust produced and is adjusted in variable-pitch systems.
Borescope Inspection
A non-invasive visual inspection using a small camera to examine internal components of propeller hubs or blades for cracks, corrosion, or wear.
C
Composite Propeller
Propeller blades made from materials like carbon fiber or fiberglass. Known for reduced weight, longer life, and increased resistance to fatigue.
Controllable-Pitch Propeller (CPP)
A propeller with blade angles that can be adjusted in flight, improving efficiency across varying speeds and flight conditions.
Corrosion Treatment
Processes used to prevent or repair corrosion damage on metal propeller components, extending service life and maintaining safety.
D
Dynamic Balancing
A procedure that corrects imbalance in the rotating propeller assembly, reducing vibration and wear.
Downtime
The time an aircraft is out of service due to maintenance. Minimizing downtime is critical for fleet efficiency.
E
Erosion Strip
A protective layer on the leading edge of a propeller blade designed to resist wear from airborne debris, rain, or dust.
Exchange Program
A service offering pre-overhauled or new propeller components to swap with customer parts, reducing downtime and cost.
F
Feathering
The ability to rotate the blades so they align with airflow, minimizing drag in engine-out situations (common in twin-engine aircraft).
FAA (Federal Aviation Administration)
The U.S. governing body responsible for regulating civil aviation, including certification and oversight of propeller repair facilities.
FBO (Fixed-Base Operator)
An airport-based business that provides services like fueling, hangaring, maintenance, and rentals—often partnering with companies like AvProps.
G
Governor
A mechanical or electronic device that controls the propeller’s RPM by adjusting blade pitch based on engine speed.
H
Hartzell Recommended Service Facility (RSF)
A repair station approved and recommended by Hartzell Propeller Inc. for meeting their rigorous standards. Aviation Propellers Inc. is proud to be the only RSF in the Southeast U.S.
Hub
The central part of a propeller to which the blades are attached. Hub inspections are critical for identifying cracks or internal damage.
I
Inspection Interval
The time or flight hours between required inspections, as specified by manufacturers or FAA regulations.
L
Leading Edge
The forward edge of a propeller blade that faces into the airflow. This area is prone to damage and wear.
Logbook Entry
Official record of maintenance, inspection, and overhaul work. Critical for maintaining airworthiness and resale value.
M
Magnaflux Inspection (Magnetic Particle Inspection)
A non-destructive testing method to detect cracks or defects in ferrous metal components of propellers.
MRO (Maintenance, Repair, and Overhaul)
Facilities or services that support aircraft component maintenance, including propeller systems.
N
NDT (Non-Destructive Testing)
Inspection techniques used to evaluate the condition of a propeller without damaging it (e.g., dye penetrant, eddy current, ultrasound).
O
Overhaul
A complete disassembly, inspection, repair, and reassembly of a propeller system to like-new condition, as required by FAA and manufacturer guidelines.
OEM (Original Equipment Manufacturer)
The company that originally designed and built the propeller or its components (e.g., Hartzell, McCauley, MT-Propeller).
P
Pitch Change Mechanism
System within a controllable propeller hub that adjusts blade angles to optimize performance.
Preload
The force applied to propeller bearings or blade retention parts during assembly to ensure proper fit and operation.
Prop Strike
When a propeller blade contacts an object (e.g., ground, debris), requiring immediate inspection and often overhaul due to potential internal damage.
R
Repair Station
A facility certified under FAA Part 145 to perform maintenance and repairs. Aviation Propellers Inc. is a Part 145 certified repair station.
RPM (Revolutions Per Minute)
A measure of how fast the propeller is spinning, regulated by the governor in variable-pitch systems.
S
Service Bulletin (SB)
Manufacturer-issued guidance or recommendations for maintenance or modifications. May be mandatory or optional depending on the FAA.
Spinner
The cone-shaped cover over the propeller hub that reduces drag and improves appearance.
T
TBO (Time Between Overhaul)
The manufacturer-specified number of flight hours or calendar time after which a propeller must be overhauled.
Track and Balance
Process of aligning and balancing propeller blades to minimize vibration and optimize performance.
Turboprop
An aircraft powered by a turbine engine that drives a propeller. Requires specialized propeller systems and services.
V
Variable-Pitch Propeller
A propeller whose blade angle can be varied in flight for better performance and efficiency.
Vibration Analysis
A diagnostic tool used to assess propeller balance and detect potential mechanical issues.
W
Wear Limits
Specified tolerances for propeller components. If exceeded, parts must be repaired or replaced to maintain airworthiness.
Z
Zero-Time Overhaul
An overhaul that restores a component to a condition equivalent to new, often resetting the service time in logbooks (subject to FAA definitions).
