What is the purpose of a leak check in a pitot-static system?

• A. To calibrate the compass.
• B. To measure the fuel pressure.
• C. To test radio communication.
• D. To verify the system holds pressure without leakage so instruments remain accurate.

Answer: (D)

The main idea here is ensuring the pressure references used by the flight instruments stay accurate. The pitot-static system provides pressure signals to the airspeed indicator, altimeter, and vertical speed indicator. If there’s a leak, those pressures can bleed away or change over time, leading to incorrect readings. A leak check verifies the integrity of the system—tubing, fittings, valves, and sensors—by applying a known pressure and confirming it remains steady without losses. When the system holds pressure, the instruments will continue to reflect true airspeed and altitude, which is essential for safe flight. The other options aren’t related to the pitot-static system: compass calibration, fuel pressure, and radio communications are separate systems.