Maintenance Diagnostic Computer (MDC)

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, The MDC-3000/-4000 units are loadable only in the repair center.  The MDT files for these units are not available to field and the specific part number of the unit determines the files that are loaded.

The MDC-3110/-4110 units are 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 new generation MDC is 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.

These benefits can be realized without requiring an expensive and time consuming re-certification of the embedded MDC software by simply updating the Diagnostic Tables loaded within the MDC.

The Diagnostic Tables are generated by the Rockwell Collins MDC team based on the aircraft type and made available for download through a standard web page browser.  

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

Maintenance Diagnostic Computer

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