EASA Part-66 Module17 propeller foundations common mistakes
EASA Part-66 Module17 propeller foundations · Understand the traps and how to avoid them.
Treating blade angle and angle of attack as identical.
Their reference directions are different.
What to do instead
State the chord, rotation plane and relative airflow separately.
Calculating percentage slip using an unstated denominator.
A distance difference is converted into a different percentage measure.
What to do instead
Use the denominator specified by the exercise and retain consistent units.
Assuming pressure loss always sends blades to fine pitch.
One design's opposing forces are transferred to all propellers.
What to do instead
Identify oil direction, springs, counterweights and the actual installation.
Measuring feather angle from the shaft but quoting a rotation-plane value.
Two complementary references are confused.
What to do instead
Keep the stated reference plane and physical alignment explicit.
Equating equal RPM with correct phase and balance.
Different system checks are treated as one measurement.
What to do instead
Assess synchronization, phase, track and balance according to their separate functions.
Calling current draw proof that every blade heats correctly.
Circuit supply is confused with correct distribution and element condition.
What to do instead
Compare the expected sequence and actual component tests under approved data.
Filing away a visible crack without approved evaluation.
Surface appearance is substituted for structural acceptance.
What to do instead
Assess the defect using the actual method, limits and authorized repair process.
Adding balance weights at a convenient unapproved location.
A generic correction direction replaces the specified structural and balance limits.
What to do instead
Use only the actual approved procedure, locations and allowed quantities.