KC-18 Mk 8 (Tanker)

Exercise 1: Major / Minor Change Classification

You are a member of the air system Delivery Team, assisting the TAA to deliver the IFF Mode 5 and ADS-B design change for the KC-18 Mk-8 aircraft.

In this first exercise you will utilise AET Tool 8I to determine whether this design change shall be classified as either Minor or Major. This will inform the level of certification effort required in the subsequent exercises.

A Minor change has no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics, or other characteristics affecting airworthiness. All other changes should be classified as Major.

AET Tool 8I (Major / Minor Change Record Template) is provided to assist the TAA or approved DO under privilege. It should be used to support the decision-making process in determining the classification of a change to the Type Design. Where the tool indicates that a change should be classified as Major, it should be used to support the Military Aviation Authority (MAA) Form 30 process.

For the purpose of this exercise, you are encouraged to complete as much of the AET Tool as possible in the time available. Therefore, if a particular section is absorbing too much time, move on and return later if time allows. There is no definitive right or wrong answer, and any issues encountered during this process will be discussed following completion of the exercise.

Once you have classified the change as either Minor or Major, you should then determine which sub-category of Minor or Major the change falls in to. Note that currently there is no AET Tool to assist with this assessment, therefore you should use your judgement to determine the most appropriate sub-category. As a reminder:

  • Minor-Minor: The change requires no review of compliance of requirements and can be delegated to Design Organisations if privileged for such activities by the TAA. These are colloquially known in the civil aviation world as “Minor-Minor” design changes. Examples include corrections to drawings, changes of part numbers, grammatical corrections to the Air System Document Set.
  • Minor: Has no appreciable effect on the mass, balance, structural strength, reliability, operational characteristics or other characteristics affecting airworthiness.
  • Major:
    • Not Significant: A Major design change that is not categorized Substantial or Significant.
    • Significant: Major Type Design change is considered ‘Significant’ if the change relates to one or more of the following: general configuration; principles of construction; or the assumptions used for Certification (including usage).
    • Substantial: A Major Type Design change is considered ‘Substantial’ if it is so extensive that a substantially complete investigation of compliance with the applicable TCB is required and a new MTC is required.

 

Design Change Technical Info

As the purpose of this design change is to include the IFF Mode 5 and ADS-B upgrade for the KC-18 Mk8 tanker based on a common IFF Mode 5 development for the C-18 CBTT, it is important to familiarise yourself with the features of the IFF Mode 5 and ADS-B, primarily how these systems differ from those they replace.

Background on the functionality of the equipment is given in the separate Information Sheet. 

More detailed information is given below. Some of this detail may not be relevant to the classification of the change but is provided to reflect the breadth of data that may be presented in a real scenario.

 

IFF Transponder model TSC2051 is replaced by TSC2002. The new model provides IFF Mode 5, up to Level 2 in accordance with STANAG 4193. Due to the new functionalities, IFF pages in MCDU (Multifunction Control Display Unit) are modified and new indications in cockpit are added.

The fixed provisions for this design change are:

  • All mechanical and electrical installation in:
    • Military Rack A800VU: to remove previous IFF Transponders and installation of permanent dummy trays in these locations.
    • Civil Rack 800VU: Installation of new IFF trays and connectors
    • Re-routing of wiring and harnesses from the Military Rack A800VU to the Civil Rack 800VU where the new IFF Transponders will be located. Also re-routing of harnesses to the Top and Bottom GPS Antennas.
    • ARO (Air Refuelling Operator) Console: Wiring adaptation to crypto load panel.
    • Avionics Bay general routings and CB panels.

The following list describes the main changes and features introduced by this design change on the A-2X8 aircraft:

  • IFF equipment (transponders) is replaced by a new P/N (Part Number)
  • Cockpit: Glareshield, Main Instrument Panel
  • Functionalities and characteristics of the new IFF Transponder:
    • Mode 5 level 1, level 2 as per STANAG 4193 Ed3
    • Mode S as per ICAO Annex 10 Amendment 85 (ED-73E)
    • ADS-B OUT as per DO-260B
    • DO-254 DAL B
    • TCAS (Traffic Collision Avoidance System) MASS (Military Airborne Surveillance System) interface
    • Dual GPS source (civil and military)
    • A/C interface requirements compliant with AC 20-165A and CS-ACNS
  • RMS (Radio Management System)
    • Upgrade of the IFF SW module in the RMS to include Mode 5 and ADS-B functionalities. This upgrade updates the HMI (Human Machine Interface) to a new version.
    • Update of the maintenance interface (with MFCD (Multi-Functional Control Display) SW Update via DCV0565S) to manage new interfaces and IFF modes failures.
  • MFCD
    • New UECs (Unic Error Code) included in the maintenance reports related to the IFF Mode 5 functionality.
  • FDIMU (Flight Data Interface Management Unit) SW update to P/N F330-002-01TT is necessary because it records a parameter related with the IFF Mode 5.