King Air MFD-85(x) Replacement

For several years, I have been asked to write proposals for the replacement of the existing Collins EFIS MFD-85(x) in various King Air 200 and 300 models. The MFD-85(x) was one of the first MFDs in widespread use and was a very nice feature back in its day.  Today, the limitations, features and capabilities of the MFD-85(x) and the entire EFIS-85 system are eclipsed by the modern flat-panel MFDs available for Part 23 aircraft.

When you are considering upgrading the MFD to a later model, keep in mind the effect that modification will have on the aircraft’s type certification. King Airs with left-hand or right-hand EFIS-85 integrated with the MFD-85(x), were designed to use MFD-85(x) for the "Reversion" capabilities built into the system. There are potentially severe consequences for removing that MFD. 

For example, if the King Air loses the left-hand DPU (Display Processor Unit) and the left-hand EFIS goes black, the system is designed so that the information feeding the failed left-hand EFIS system is also feeding the MPU (Multifunction Display Processor) and that information can be displayed on the MFD-85(x). 

Removal and retrofit of the MFD-85(x) with any of the modern displays will take that "Reversionary" function away, rendering the aircraft not in compliance with its original design and type-certification.

I have seen retrofits of this type performed and Field-Approved by a local FAA Inspector and the customer walks away thinking he is perfectly legal to operate the aircraft in this manner. It is not until he goes to sell the aircraft or place it on a 135 certificate that a savvy Chief Inspector or FAA Inspector finds that the aircraft is not operating in accordance with the Airplane Flight Manual Supplement (AFMS) for the Collins EFIS-85, which was inserted in the Flight Manual by the Beechcraft when the airplane left the factory.  Now the trouble begins.

The bottom line is, when considering an upgrade to the MFD and your King Air has a Collins MFD-85(x), make sure there is either an STC for the installation or the existing EFIS-85 AFMS will allow for the removal of the MFD-85(x).