EASA Part-66 Module17 propeller foundations cheat sheet
EASA Part-66 Module17 propeller foundations · Keep the key ideas within reach.
Blade geometry, forces and construction
Blade angle and aerodynamic angle of attack use different references.
Slip is geometric pitch minus effective pitch at the stated condition.
Useful thrust power and shaft input power are different quantities.
Loads, retention and control forces must be considered together.
Construction and measurement references are model-specific.
Governing, feathering and ground pitch control
Constant speed does not mean constant thrust or aircraft speed.
On-speed, overspeed and underspeed describe the relation to a selected RPM.
Oil-to-coarse and oil-to-fine designs must not be interchanged.
Feather angle must retain its stated reference plane.
Ground beta/reverse safeguards and test procedures are installation-specific.
Synchronization, phase and ice protection
Synchronization matches speed; synchrophasing also controls relative phase.
Equal RPM does not prove correct balance or blade condition.
Actual engagement and failure rules vary by installation.
Use the specified anti-icing fluid and designed heating sequence.
Electrical current alone does not prove correct heating on every blade.
Inspection, balance, damage and preservation
Tracking, static balance and dynamic balance are distinct checks.
A vibration clue is not a unique diagnosis.
Damage acceptance and cumulative material removal depend on actual limits.
Impact or overspeed can require evaluation without visible exterior damage.
Identification, history and specified preservation matter to continued airworthiness.