What is the suction gauge reading for the aircraft's vacuum system?

What is the suction gauge reading for the aircraft's vacuum system?

• A. 3.0-4.0 inHg
• B. 4.0-4.9 inHg
• C. 4.5-5.4 inHg
• D. 5.0-5.9 inHg

Answer: (C)

Suction gauges in aircraft measure how much negative pressure the vacuum pump is producing to drive the gyros. In most systems, the normal operating range is about 4.5 to 5.4 inches of mercury. A reading in this window means the pump is producing adequate suction for the instruments to stay accurate. If the gauge drops below this range (too low), it suggests leaks, a restricted line, or a weak pump. If it climbs above this range (too high), it can indicate over-suction or a fault in the system that could stress components. So, 4.5–5.4 inHg reflects the typical healthy level for the vacuum system.

Suction gauges in aircraft measure how much negative pressure the vacuum pump is producing to drive the gyros. In most systems, the normal operating range is about 4.5 to 5.4 inches of mercury. A reading in this window means the pump is producing adequate suction for the instruments to stay accurate. If the gauge drops below this range (too low), it suggests leaks, a restricted line, or a weak pump. If it climbs above this range (too high), it can indicate over-suction or a fault in the system that could stress components. So, 4.5–5.4 inHg reflects the typical healthy level for the vacuum system.