Assistant chief engineer
The assistant chief engineer or assistant engineer was the primary assistant or backup to the chief engineer.

In situations when the chief engineer was away from the engine room, the assistant chief engineer was responsible for overseeing engineering until the chief engineer returned. ()

If a chief engineer was either incapacitated or killed in action, the assistant chief engineer was made chief engineer. ()

List of assistant chief engineers 

 Lieutenant Hess (2151)

 Lieutenant DeSalle (2267)
 Lieutenant Cleary (2270s)

 Jim Shimoda (2364)
 Lieutenant junior grade  (2364)
 Ensign Clancy (2365)
Varro generational ship
 Derran Tal

 Lieutenant Joe Carey (2371-2378)
Unnamed Y-500 class freighter
 George Webb

Titles

fr:Chef-ingénieur assistant
nl:Assistent hoofdingenieur