Define bleed port and its function in an air start system.

• A. A venting/bleed point that releases trapped air from the starting circuit to ensure proper pressure and reliability of starting.
• B. A fuel supply valve that controls fuel flow to the starting system.
• C. An oil passage to lubricate the starter motor.
• D. A pressure relief for the lubrication system.

Answer: (A)

A bleed port in an air start system is a venting point that releases trapped air from the starting circuit to ensure proper pressure and reliability of starting. When the system is charged, pockets of air can remain in the lines or at the starter, causing hesitations or inconsistent starting because the air doesn’t reach the starter uniformly. The bleed port provides a controlled path to vent that air, allowing the starting circuit to reach and maintain the correct pressure so the starter operates smoothly and reliably. This function is about air removal in the starting circuit, not about fuel supply, lubrication passages, or lubrication pressure relief, which is why those other ideas don’t fit.