Which document pertains to aircraft inventory?

The document that pertains to aircraft inventory is the 2408-17. This specific document is recognized for its role in the management and tracking of aircraft parts and equipment. It plays a vital part in maintaining accurate records of all components associated with aircraft, ensuring that maintenance personnel have access to up-to-date information regarding the inventory status. This documentation supports effective maintenance practices, helps prevent shortages or overstocking of critical components, and ensures compliance with aviation regulations.

In terms of the other options—while the remaining documents like 2408-15, 2408-19, and 2408-21 are also related to maintenance and logistics in aviation, they do not specifically focus on the inventory management of aircraft parts. Thus, 2408-17 is the right choice for addressing aircraft inventory specifically.