Both TCAS systems from ACSS have Change 7 mods available.
The TCAS II Computer Unit (RT-910, P/N 4066010-90X) will need a hardware and software modification. This can only be done by ACSS-authorized Repair and Overhaul facilities. See Representatives contact information at each location. The Customer Service Representative can provide scheduling and pricing information at each of the Service Center locations.

The TCAS 2000 Computer Unit (RT-950/RT-951, P/N 7517900-XXXXX) will need only a software modification. This software may be installed using one of the three methods: an airborne ARINC data loader, an ARINC portable data loader used at the aircraft, or by an authorized Service Center location. If the Service Center method is desired, please see the service center page at
http://www.l-3com.com/acss/service/

More detailed information is available by downloading the following Technical Newsletter detailing Change 7 issues.

Click Here to Download the Change 7 TNL Publication C23-9000-040.

For regulatory information please use the following link to the ACAS Eurocontrol Website at the following URL, http://www.eurocontrol.be/projects/eatchip/acas/.
Change 7
Change 7 is an upgrade to the TCAS system to incorporate improvements defined by the United States Federal Aviation Administration (FAA) from observations of TCAS systems in operation. This change, while not being mandated by the FAA as of yet, is required to meet upcoming Airborne Collision Avoidance System (ACAS) mandates in Europe (forms for extension Submittal are available). ACAS is basically the European acronym for TCAS with Change 7 incorporated. TCAS with Change 7 is designed to meet ARINC 735A specifications. The current TCAS units are designed to meet the ARINC 735 specifications.