Boeing Takes uncommon Approach
Boeing's CH-47F and MH-47G are leading an unprecedented effort to field a common glass cockpit across a range of helicopters operated by the US Army and other services.
Called the Common Avionics Architecture System (CAAS), the cockpit has been developed by Rockwell Collins and uses technology from its commercial Pro Line 21 integrated avionics suite.
The result is a cockpit that would not look out of place in a business jet or regional airliner, but provides a full range of military functions including mission management, sensor display, datalink communications and weapons control.
CAAS became operational early in 2007 in MH-47Gs and Sikorsky MH-60K/Ls operated by the US Army's 160th Special Operations Aviation Regiment (Airborne). The CH-47F followed later in 2007.
The system has also been selected for US Army Bell ARH-70A armed reconnaissance and Sikorsky UH-60M tactical transport helicopters, US Marine Corps Sikorsky CH-53E/K heavylift and VH-60N VIP helicopters, and US Coast Guard MH-60T search-and-rescue helicopters.
In each application the overall architecture and avionics functionality is similar, with interchangeable hardware and reusable software. The system scales from five displays in the Chinook to two in the ARH.
CAAS was initially developed to update the 160th's MH-47s and MH-60s to a common cockpit with a more maintainable and upgradable open systems architecture based on commercial standards.
The basic backbone is a switched Ethernet communications network connecting distributed mission processors in the multi-function displays and control display units. The CDUs communicate with existing avionics via 1553B databus. Layered and partitioned software allows individual modules to be added or updated, and new functions to be reused across all CAAS-equipped helicopters.
"If it's two displays versus five, the part numbers are identical. The software is the same, only not as redundant. The capability and the functionality are the same," says Daniel Toy, marketing manager, army programmes, for Collins.
Almost all avionics, communications, sensor and weapons management is via the CAAS controls and displays. The liquid-crystal MFDs present all primary flight information, as well as engine instruments and crew alerts.Communication and navigation management is via the CDUs.
Display symbology is not identical across CAAS-equipped types, but "the menu structure is largely the same, with information laid out in a fairly consistent manner", says Toy. "They have not agreed a single software build across all applications, but there is the possibility of convergence in the future."
The open, standards-based architecture will allow third-party software to be developed for CAAS. Already Northrop Grumman is working with Collins to develop a software module for special-operations helicopters that will provide an advanced situational-awareness capability for covert penetration. As new functionality is developed, it will become available for reuse.