The US forces are continuing a long-term policy of upgrading and refurbishing ageing transports to extend their livesby 35-40 years. But for large fleets of transport aircraft, life extension is no longer confined to modifications that assure continued structural integrity. Civil communication, navigation and surveillance/air traffic management modernisation is mandating new avionics packages, referred to as global air traffic management (GATM). Coupled with this is increasing pressure to enhance mission readiness and performance at lower life cycle costs.

"Because of the lack of procurement in the 1990s, we need to maximise the resources of an ageing fleet and find ways to assess system problems through better onboard diagnostics and improved training," says Bob Ernst, US Navy ageing aircraft integrated product team leader. "At the same time, we have groups working on open architecture solutions for the integration of new technologies."

For older transports, this has meant procurement of new avionics which leverage the civil technologies.

Says Dan Reida, Universal Avionics Systems' director airline/military marketing: "The military realises that if they operate in commercial airspace and there is a problem, they will need to have compliant equipment or face greater scrutiny. They are showing more interest in complying with the evolving civil airspace requirements."

Key Universal equipment for military transport upgrades is the UNS-1F flight management system (FMS), a digital system that can interface with older, analogue equipment. It is in use on military variants of business jets and airliners, as well as the Lockheed Martin C-130 Hercules and P-3 Orion. Reida says Universal's terrain avoidance warning system (TAWS) and multifunction display have also found significant usage.

"The trend is definitely toward [the use] of commercial off-the-shelf products that could be reconfigured for the military, both as replacements and add-ons," says Reida. "And because most military transports will be used for many years, there is an increased interest in upgrading the classic aircraft with commercial, state-of-the-art products."

Joe Longworth, director of commercial to government sales at Honeywell Aerospace Electronics, agrees: "This is particularly true for military derivatives of commercial transports, such as the [Boeing] KC-135 and [McDonnell Douglas] KC-10 tankers, and the [Boeing] T-43 navigator trainer. These are ageing airframes that are candidates for commercial aircraft avionics systems which meet the new civil [air traffic management] mandates." Longworth and Reida say military sales now make up a significant volume of their companies' sales.

Honeywell is supplying a new KC-10 cockpit based on its Versatile Integrated Avionics package. The KC-10's analogue cockpit is replaced by a digital system that includes a derivative of the company's commercial Pegasus FMS with software reconfigured for the in-flight refuelling mission. Also introduced are four liquid-crystal displays based on Honeywell's commercial system. The package also has an enhanced ground proximity warning system, (EGPWS), traffic collision avoidance system and a communications datalink - all derived from commercial products. "New digital systems will give the aircraft increased reliability and maintainability, and will meet GATM requirements," says Longworth. Systems reliability can increase 30-fold, he adds.

Reliability and affordability are the incentives behind military avionics upgrades for transports, says Richard Eisenhart, Rockwell Collins' director of engineering government systems.

"The military is extending the life of nearly every aircraft it has in service today, and has shifted its concern away from the acquisition costs of new avionics toward life cycle costs," says Eisenhart. He adds that the Rockwell Collins-supplied Flight2 avionics suite for the KC-135 tanker GATM upgrade is based on the company's civil ProLine 21 technology.

The USN is extending the service life of 36 Grumman C-2 Greyhound carrier onboard delivery aircraft to keep them operational until 2015-20. In conjunction with this, the aircraft will be fitted with new avionics.

Scott Goldberg, C-2 Level One integrated product team leader at North Island Naval Air Depot, San Diego, says the aircraft will receive two Rockwell Collins R210 dual-mode UHF/VHF radios, as well as a Northrop electromechanical inertial navigation system and a single Rockwell Collins multifunction display, TAWS and TCAS.

The aircraft's twin Rolls-Royce T56-425 turboprops will remain, but will be fitted with the same eight-bladed Hamilton Sunstrand propellers being fitted to the C-2's sister-design, the E-2 Hawkeye.

Goldberg says structural enhancements will be carried out during full-scale depot maintenance and will include new wiring as well as repairs and enhancements. The North Island facility will perform all engineering oversight and production, while Northrop Grumman carries out fatigue tests, design and engineering.

Meanwhile, the USAF's Lockheed C-5 Galaxy transport is receiving an avionics modernisation programme (AMP) and reliability enhancement/re-engining programme (RERP) that will keep the aircraft operational until 2040.

The AMP includes FMS, seven multifunction displays, an upgraded flight control system and autopilot. Other enhancements include an embedded global positioning system/INS, EGPWS and TCAS. Honeywell provides the core processor and software partitions, but Lockheed Martin Aeronautics will provide the software to integrate the display units.

The first software load was installed last December, and a second block is due to be flown next month. "We will be developing and testing additional blocks of software through year-end 2003, with verification testing to be done and concluded by third quarter 2004," says June Shrewsbury, vice-president strategic airlift, Lockheed Martin Aeronautics. "Four blocks are scheduled for development, with installation of the [final] software slated for the summer of next year."

The production software will be installed on eight aircraft by 2005. If funding permits,112 aircraft should receive the avionics package by 2007.

The RERP will replace the 41,000lb-thrust (182kN) General Electric TF39-1C with the same company's CF6-80C2, derated from 60,000lb to 50,000lb-thrust to minimise life cycle costs. Along with better performance, the new engines will meet Stage III noise standards.

Lockheed Martin has completed preliminary design, with the critical design phase to be completed in December. Engine installation will begin late next year, with the first flight scheduled for October 2005. A low-rate initial production decision will be made by 2006, with the actual number of aircraft to be retrofitted depending on available funding.

Shrewsbury says 73 improvements targeting 53 areas of reliability enhancements have been defined. The major systems include fuel, hydraulic and electrical systems, as well as environmental/pneumatic, flight controls and landing gear. Also included will be an inspection of the keel beam and aft fuselage skins, with any necessary repairs.

Source: Flight International