MDT (Maintenance Diagnostic Tables)

The Rockwell Collins Maintenance Diagnostic Computer (MDC) is the central component of an aircrafts Maintenance Diagnostic System (MDS). The purpose of the MDC is to aid the aircraft users and maintenance personnel in detecting and troubleshooting avionics components and/or wiring failures.  The MDC performs its function by monitoring avionics system LRUs to capture failure conditions and then isolate failures to specific LRUs or to the wiring between components.  The MDC logs (or stores) failure information and makes it available for viewing on the Multi-Function Display or makes it available for downloading (to a floppy disk or PC) where it can then be viewed or printed.

There are two series of MDC units:

  • MDC-3000/-4000: Not Field Loadable.
    • MDT's must be loaded at the service center. The specific part number of the MDC determines the MDT files that are loaded.
  • MDC-3110/-4110: Field loadable.
    • One of the unique features of the new generation MDC is that it has been designed to be configurable based on the aircraft type on which it resides.  The MDC-3110/-4110 are configured through the use of field loadable Diagnostic Tables.  The Diagnostic Tables define fault “equations” that the MDC software uses when processing LRU inputs in order to determine and isolate the actual avionics failure conditions.

Having field loadable Diagnostic Tables for the MDC provides several major benefits to the end user:

  1. The MDC can be easily updated to account for aircraft equipment changes.
  2. The MDC can be easily updated to eliminate nuisance failure annunciations.
  3. Users with more than one aircraft type can re-use MDCs across those aircraft by simply re-loading the correct Diagnostic Tables into the MDC. Refer to Service Information Letter MDT-3110 SIL 1-04 for part number to type information.

When a new MDC is installed and powered-up on an aircraft for the first time, no Diagnostic Tables are installed and the user is guided through the table installation process.  Typically, the Diagnostic Tables only need to be changed (or re-installed) when the aircraft equipment changes, when nuisance failure conditions occur and need to be eliminated or when an MDC is moved from one aircraft type to another.

MDC Diagnostic Tables Load Procedure

​​​​​​​If you are unsure of the MDT you need, please contact your Aircraft OEM to determine your MDT part number.

If your MDT is missing from this list please contact: with the table part number and the aircraft type it is used on. Your request will be verified, if valid it will be posted. Please allow 24-48 hours for your table to be added to this list for download. 

Maintenance Diagnostic Computer

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