What is the SSSn related to APU emergency shut down procedures?

The SSSn, or Supplemental Safety Sheet number, related to APU emergency shutdown procedures is essential to ensure crew members have immediate access to critical safety information during such situations. In this context, the correct value ties directly to the specific procedures and guidelines regarding the Auxiliary Power Unit's safe shutdown in emergencies.

Accessing the accurate SSSn ensures adherence to protocol, which is crucial for safety in operations. Each of the SSSn values corresponds to various technical and operational topics, but the one associated with APU emergency shutdown procedures specifically outlines the necessary steps and safety measures that need to be followed, making it an integral component of training and emergency response.

In terms of the context surrounding the other values, they may relate to different systems, procedures, maintenance guidelines, or operation instructions that do not pertain to the emergency protocols for the APU, distinguishing them from the relevant and critical information found in the correct answer.