What is the first step in the air pressure build-up test procedure?

The first step in the air pressure build-up test procedure is to fully charge the system to the governor cutout pressure. This means the air brake system must reach the pressure level at which the air compressor stops providing additional air to the system, ensuring it is fully charged before proceeding with further testing. A full charge is necessary to validate the performance and functionality of the air brakes, allowing for an accurate assessment of the system's capabilities under normal operating conditions.

Starting with this step establishes a baseline and ensures the air system is working properly before any measurements or checks are made, such as releasing the brakes or checking pressure levels at the governor cut-in point. Engaging in any testing or releasing brakes without achieving the proper charge could lead to inaccurate results or a misunderstanding of the system's functionality.