The Honeywell MK III CMU will be replaced with the Honeywell MK II+ CMU. Both units have the same form factor and connector, i.e. the existing mounting tray and connector will be reused. The Aircraft Personality Module (APM) used for the MK III CMU will be reused for the MK II+ CMU.

Additional electrical wiring will be added, e.g.:

   Connections between the CD-830 CDUs and the MK II+ CMU

   Connection to the TR-866B VDR

   ARINC 429 interface to the Mode S transponders for the CMU to receive the ICAO 24-bit aircraft address (required for ATN B1)

   Weight-On-Wheels signal (if not already present on the CMU)

   Interface to the GPS system (if not already present on the CMU)

   New interface from the CDU to the aircraft Aural Warning Unit (AWU) input currently used for FANS

NOTE: Special Condition H-01 Enhanced Airworthiness Programme for Aeroplane Systems – ICA on EWIS is not applicable to EMB-135BJ

The currently installed 3^rd VHF radio (Honeywell RCZ-833), used for voice and Mode A data link services, is kept in the aircraft. An additional VDL 2 radio (Honeywell TR-866B) will be installed to provide Mode 2 data link communications for PM-CPDLC. The 3^rd COM and the VDR will share the VHF antenna, currently dedicated to the 3^rd COM. An Antenna Switching Unit (ASU) will be installed, operated by a dedicated lighted pushbutton switch which will be installed in the cockpit. All data link communication, currently routed via the RCZ-833, will be handled by the TR-866B after the modification, i.e. the connection between CMU and RCZ-833 will be removed.

NOTE: Since the TR-866B (Honeywell Primus EPIC^®) cannot be tuned in voice mode by the Radio Management Unit, but by the CMU via the CDU, a replacement of the RCZ-833 with the TR-866B would also be an option, depending on aircraft specific procedures and MEL regarding the 3^rd voice COM for emergency operation.

The currently implemented ATC message annunciation on the Primary Flight Display can only be used for FANS, not for PM-CPDLC. Therefore it will be de-configured in the IM-600 Symbol Generator and replaced by new external ATC MESSAGE annunciators which will be installed above each PFD. Those annunciators will be used for either FANS and PM-CPDLC incoming messages, since EASA CS-ACNS requires dual stack systems to demonstrate common flight deck indications for incoming FANS 1/A and ATN B1 messages.

NOTE: A dual stack system in this case is a dual system that uses manual selection with an interlock system.

NOTE: The ATC MESSAGE annunciators are kept in the primary field of view to provision for a future extension of CPDLC use beyond en-route flight phase, where this would become a requirement.

The part number of both Flight Management Systems will be changed from 7018879-03038 or 7018879-03044 (depending on the aircraft configuration) to 7018879-03046 by applying a Honeywell Service Bulletin for a software update which installs the FANS Latency Timer.