What is the purpose of the APU Accumulator?

What is the purpose of the APU Accumulator?

• A. provide a hydraulic charge to the APU start motor
• B. cool the hydraulic fluid
• C. provide electrical power to the APU
• D. store hydraulic fluid for the main pumps

Answer: (A)

The APU Accumulator is a hydraulic energy storage device used to deliver a rapid, stored charge to the APU start motor. When the APU is commanded to start, this precharged hydraulic fluid is released from the accumulator into the APU start motor, providing the initial torque to spin the APU up to speed so ignition can occur. Once the APU reaches operating speed, it can supply electrical and hydraulic power as needed. The other options don’t fit because the accumulator’s job is not to cool hydraulic fluid, not to provide electrical power to the APU (that comes from the generator system once running), and not to store hydraulic fluid for the main pumps (that’s the role of the hydraulic reservoir/system, not the accumulator).

The APU Accumulator is a hydraulic energy storage device used to deliver a rapid, stored charge to the APU start motor. When the APU is commanded to start, this precharged hydraulic fluid is released from the accumulator into the APU start motor, providing the initial torque to spin the APU up to speed so ignition can occur. Once the APU reaches operating speed, it can supply electrical and hydraulic power as needed.

The other options don’t fit because the accumulator’s job is not to cool hydraulic fluid, not to provide electrical power to the APU (that comes from the generator system once running), and not to store hydraulic fluid for the main pumps (that’s the role of the hydraulic reservoir/system, not the accumulator).