The Collins Aerospace RTU-42XX Radio Tuning Unit product family provides integrated control of all Collins Pro Line II and 400 Series Communication, Navigation and Surveillance (CNS) sensors and the HF-9000. The RTU-42XX incorporates a complete set of radio management functions into a single unit and gives you a convenient means of selecting frequencies, codes, channels, operating modes and volume.
You can integrate the RTU-42XX with the Flight Management System so that the tuned frequency is always displayed on the RTU regardless of the tuning source.
The RTU-42XX’s maintenance display pages for the CNS system can interface status, radio diagnostics and fault history records. The unit offers an optional backup Horizontal Situation Indicator display. Some original equipment manufacturer versions of the RTU-42XX can even serve as a backup engine data display.