What instrument or indicator signals a hydraulic system pressure loss that could affect gear operation?

• A. A low hydraulic pressure warning or gauge reading, plus abnormal gear position or warning horn if installed.
• B. A loud cabin noise and seat vibrations.
• C. An unexpected rise in fuel consumption.
• D. No indicator; gear operates regardless.

Answer: (A)

When hydraulic pressure drops, the gear system may not extend or retract reliably, so pilots rely on direct indicators of both pressure and gear status. The best signal is a low hydraulic pressure warning or a gauge reading that shows the pressure has fallen below safe operating levels, often accompanied by the gear position indicating an abnormal or not-fully-deployed state. Some aircraft also provide an audible warning horn to alert crew when hydraulic pressure is abnormal.

Other signs like cabin noise or seat vibrations aren’t specific to landing gear hydraulics and can come from many different sources. A rise in fuel consumption isn’t a direct indication of hydraulic pressure affecting the gear, and operating without any indicator would be unsafe because you wouldn’t know the system status.