In case of failure of both the left and right hydraulic systems, how many brake applications can the accumulators provide pressure for?

The accumulators in an aircraft's hydraulic systems are designed as a backup source of pressure for critical systems, including the brakes. In the event of a failure of both the left and right hydraulic systems, the accumulators can typically provide sufficient pressure for only one brake application. This is because the accumulators store a limited amount of hydraulic fluid under pressure, which is meant to ensure that in the case of a total hydraulic failure, the aircraft can still come to a stop.

After the initial application of brakes using the stored pressure from the accumulators, the fluid is depleted. Therefore, there wouldn't be enough hydraulic pressure left for subsequent brake applications. This design ensures that, even under failure conditions, the pilot has at least one chance to stop the aircraft safely. Understanding this limitation is critical for pilots and maintenance personnel when considering emergency procedures and system capabilities in the event of hydraulic failure.