EASA ATPL021 aircraft general knowledge foundations study materials
EASA ATPL021 aircraft general knowledge foundations study resources

EASA ATPL021 aircraft general knowledge foundations common mistakes

EASA ATPL021 aircraft general knowledge foundations · Understand the traps and how to avoid them.

Mistake 1

Assuming every fly-by-wire mode retains identical protection.

A signaling architecture is mistaken for a universal control law.

What to do instead

Read the actual aircraft mode, available inputs and stated functions.

Mistake 2

Inferring normal actuator speed from pressure alone.

Stored pressure is confused with delivered flow.

What to do instead

Check effective area, actual flow and the circuit conditions before calculating movement.

Mistake 3

Calling a PTU an unlimited backup energy source.

Power transfer is confused with power generation.

What to do instead

Identify the available driving source and the circuits linked by the actual design.

Mistake 4

Assuming more torque always means more governed RPM.

Torque and rotational speed are confused.

What to do instead

Apply the stated constant-speed governing condition and distinguish torque, speed and power.

Mistake 5

Giving one oil-flow direction for every constant-speed propeller.

One installation is generalized to all propellers.

What to do instead

Use the specific propeller architecture and approved description rather than a universal hydraulic claim.

Mistake 6

Using a summed FMS quantity as an independent confirmation of the same gauges.

A derived display is mistaken for an independent sensor.

What to do instead

Identify the input source before treating a second display as corroboration.

Mistake 7

Opening a generic crossfeed to prove or correct every imbalance.

Engine feeding and tank transfer are treated as identical functions.

What to do instead

Use the actual fuel diagram and approved procedure; the generic symptom does not establish one safe action.

Mistake 8

Treating a theoretical fuel-time result as authorized endurance.

A classroom quotient is confused with required reserves and real operating conditions.

What to do instead

State the given assumptions and separately identify operational requirements not supplied.