If hydraulic pressure loss affects flight controls, which advisory could indicate loss of control authority?

• A. SAS OFF
• B. FPS FAIL
• C. HYD PUMP 2 FAIL
• D. PRI SERVO 2 FAIL

Answer: (A)

When hydraulic pressure is compromised, the flight control system loses its assist and the stability augmentation system (SAS) can’t operate. The SAS provides automatic damping and stabilization, reducing pilot workload and helping the helicopter respond predictably to control inputs. If SAS can’t function, you’ll feel the aircraft manage more on its own, and manual control becomes harder, which is a direct sign of reduced control authority.

The advisory that SAS is OFF is the clearest indicator that the stabilization and hydraulic-assisted controls aren’t available. Other advisories point to specific subsystems or failures (like a particular hydraulic pump or a flight path/autopilot function) but don’t as directly signal that the overall control authority is degraded due to loss of hydraulic stabilization. So SAS OFF best aligns with a loss of control authority stemming from hydraulic pressure loss.