What is the role of the fuel control unit in a turbine engine overhaul and what checks are typically performed on it?

• A. It meters oil flow to bearings; checks include viscosity.
• B. It meters fuel to meet commanded speed schedules, but does not require FADEC tests.
• C. It meters fuel to meet commanded speed schedules; checks include calibration, flow limits, leak testing, actuator operation, and FADEC compatibility tests.
• D. It controls ignition timing and spark energy.

Answer: (C)

The fuel control unit’s job is to meter fuel to match the commanded engine speed and power. It takes control signals from the FADEC and engine sensors and adjusts fuel flow through the metering valve and actuators so the engine follows the desired schedule while staying within safe limits.

In an overhaul, you check calibration to ensure the unit delivers the precise fuel amounts for each commanded setting, verify flow limits to prevent over- or under-fueling, perform leak testing to detect any fuel leaks, confirm actuator operation across the full range and in response to control signals, and run FADEC compatibility tests to ensure proper communication and correct metering behavior under digital control.

This is distinct from systems that meter oil to bearings or control ignition timing, which are outside the fuel control unit’s role.