Control systems and methods to secure maintenance access to aircraft control system. The aircraft control system includes a control node operably coupled to an engine health monitoring node that includes a maintenance port. The aircraft control system also includes an enclosure preventing physical access to the maintenance port. The enclosure includes a key lock that, when activated, allows for physical access to the maintenance port. The engine health monitoring node can determine whether to allow a maintenance port data transfer access request to transfer data across the maintenance port based on the validity of received credentials, such as a password. The engine health monitoring node can also determine whether to allow or disallow encrypted or unencrypted data transfers based on whether a keep alive message is periodically received. The engine health monitoring node can also store data related to the maintenance port data transfer access request to memory.