The ___ caution indicates the majority of AFCS has shut down

• A. AFCS OK
• B. AFCS FAIL
• C. FCC FAIL
• D. STAB FAIL

Answer: (D)

The main idea here is how the helicopter’s automatic flight control system uses stability augmentation to keep the aircraft steady. The stability augmentation system (STAB) provides automatic damping and trim to help maintain stable flight. If most of the AFCS channels are down, that stabilization capability can no longer be relied on, and the cockpit warning you’ll see is a STAB FAIL.

So, STAB FAIL means the stability augmentation portion of the AFCS has failed or degraded, signaling to the pilot that automatic stabilization isn’t available and manual control will be required. The other cautions would indicate different issues: AFCS OK means normal operation, FCC FAIL points to a flight control computer problem, and AFCS FAIL would signal a broader AFCS failure rather than specifically the stabilization function.