At the end of 2003, the Air Force transport fleet included 112 C-17, 124 C-5, 45 C-141, 449 C-130, 59 KC-10 and 543 KC-135 airlifters and cargo/tanker aircraft. Of those, only the C-17 is still in production, with Boeing’s current multi-year production contract calling for delivery of 180 aircraft through 2008. However, General John Handy, commander of the U.S. Transportation Command and Air Mobility Command, has said the military needs a minimum fleet of 222 C-17s.

All transport assets were called into heavy use during OEF and OIF, with the C-5 handling about 48 percent of cargo shipments into both theaters. The C-17 also played a significant role there by joining the C-130 on intra-theater deliveries straight to the front. The C-141 role in Iraq increased significantly in the second half of 2003, as the other airlifters were gradually drawn down. The KC-10 and KC-135 were hailed as the unsung heroes of both conflicts for keeping the transport and combat air fleets refueled around-the-clock.

The C-5

The Pentagon’s stated goal is to keep the C-5 structurally sound and flying through at least 2040. A consortium of users and maintainers in all commands, known as the Requirements and Planning Council, meets regularly to identify and prioritize issues that need to be addressed to meet that goal. Those are then passed on to the Air Mobility Command, which uses the Council’s recommendations to determine which programs to implement during each program objective memorandum cycle.

At present, that list includes several additional modification and upgrade programs to the emergency power system, hydraulic surge valves, malfunction analysis detection and recording system, as well as various software sustainment upgrades, global air traffic management (GATM) modifications and a variety of ongoing sustainment activities, such as an anti-skid modification for the landing gear, thrust reverser modifications, etc.

About 30 items on that list have not yet been funded—some are not immediately necessary. The requirement for GATM, for example, won’t occur until 2010, but it is essential in enabling aircraft to operate in more direct and desirable routes through crowded international airspace.

Two of the largest modifications programs are the Avionics Modernization Program (AMP), which will run from June 2004 and through 2007, and the Reliability Enhancement and Re-Engining Program (RERP), which will begin when AMP is completed. The RERP system design and demonstration phase began in 2000 and runs through 2008, although the major activity will be concluded by 2007. Three aircraft will be modified during that time. While neither program is designed to extend the life of the airframe, they are intended to substantially enhance reliability and performance while meeting stricter airspace regulations over Europe.

“There are 114 C-5s scheduled for the avionics mod; two of those were done during development, and 112 will be completed during production,” Lieutenant Colonel Francis Geiser, chief of the Modernization Division at the Warner-Robbins Air Logistics Center, Robins AFB, GA, said.

“The Air Force position is that all 114 will get the new engines, but that stretches out through 2017, and there are no DoD or White House approved budgets that run out that far. In 2010, someone may decide to retire some of the fleet instead.”

At present, only the 50 B models, the newest in the fleet, have been budgeted for the engine and cockpit upgrades, at which point they will be redesignated as C-5M.

“The glass cockpit for the C-5 is in the latter stages of development, with flight tests on the second stage of software,” said program deputy director Al Fatkin. “That digitizes the cockpit and installs the Global Air Traffic Management system required by the International Civil Aviation Organization for better navigation and communication.

“There will be an all new multifunction display replacing the analog dials, and the flight management system will be replaced by one from Honeywell (the Versatile Integrated Avionics platform). It also will have terrain collision avoidance and new digital radios (replacing the 25 Hertz system with 8.33 and SATCOM) that will allow us to fly in international airspace in Europe.”

When an aircraft is scheduled for AMP, the user command gives up ownership to the Air Force Materiel Command, which is then also responsible for any other repairs that may be required while in their possession. The average time from handover to return will be about 12 weeks when the program first begins, but program officials predict the learning curve will bring that down to about eight weeks by the time it is operating at full rate.

“My division manages the production line, working any legacy issues and to liaison with the local base for support,” Geiser says. “It’s a very tightly scheduled line because we can’t keep these aircraft out of service any longer than necessary. Approximately three acceptance flights are conducted after the mods are complete and before the aircraft is returned to the using command.”

The installation sites for AMP will be at Dover AFB, DE, and Travis AFB, CA.

“For RERP, it is anticipated each aircraft will be out of service for about one year for re-engining,” Geiser said. “When it gets into steady state, we will induct three aircraft each quarter, so we will be working on 12 during each year.”

The current General Electric TF39 will be replaced with GE’s CF-6 engine, which is standard on many large commercial airliners.

“The big part remaining is designing of a new pylon to handle the increased thrust of the engine. That is now in critical design review and in about a year they will start flight testing,” Fatkin said of the effort now underway by B.F. Goodrich Aerostructures Group, Chula Vista, CA.

“The re-engining will increase reliability, driving them to higher mission capable rates, including cost savings from reduced fuel consumption. They also will stay on the aircraft longer than the old engines before they have to be overhauled.”

Lockheed Martin, Marietta, GA, which built the C-5, is the prime contractor on RERP during the development phase, although no contract has yet been awarded for the actual re-engining effort.

About 50 other reliability modifications also are part of RERP, including one to bring the actuator and valves back up to their original reliability.

“Every time you overhaul a component, you may not get it back to its original capability, so the idea is to get those parts back to like new configuration or improve the design if there have been improvements in the materials or technology,” Fatkin explains.

Another is a new Hamilton Sundstrand, Windsor Locks, CT, APS 3400 auxiliary power unit, incorporating a dual (left- and right-hand) silicone elastomer isolation system developed by Lord Aerospace, Cary, NC, for the Airbus A340-500/600 commercial aircraft and Dassault Falcon 7X programs.

What About Us?

The C-141C also has been upgraded to carry the remaining 46 aircraft in the fleet through to a scheduled retirement in 2006. That program, which installed a new glass cockpit, has now been completed, giving each aircraft a new All-Weather Flight Control System consisting of a digital autopilot, advanced avionics display and Ground Collision Avoidance System.

Destined for a much longer continuation of its 45 years in service is the KC-135, with only three of the fleet’s 490 aircraft remaining before its own re-engining program concludes in FY05. The Air Logistics Center, Tinker AFB, OK, will complete two of those this year, replacing the old Pratt & Whitney TF33 engines with General Electric F108s, a military version of the popular CFM56-2 commercial engine.

The KC-135 fleet, which was heavily exercised in OIF, recently acquired the new “Pacer CRAG” (compass, color weather radar and embedded GPS/INS) cockpit, which also includes reduced vertical separation minima, an enhanced traffic collision avoidance system, a terrain awareness warning system and navigation safety upgrades - flight data recorder/cockpit voice recorder/ emergency locator transmitter.

The next cockpit addition is GATM, in a program extending through the end of 2015 and preparing the KC-135 to continue its dual global operations role as both tanker and airlifter.

C-17

The C-17 has been in a constant state of block upgrades throughout its production life. As a result, Air Force officials say if a design issue were to result in an order to ground all involved C-17s, the likelihood is that it would impact only a fraction of the fleet that began entering service in 1995.

Two major upgrades are planned for the C-17 by Boeing Integrated Defense Systems in the coming decade—a modernized flight control computer to give it GATM compliance and a spoiler control electronic flap computer. Development began with a systems integration award to BAE SYSTEMS Platform Solutions (Johnson City, NY) in April 2003. BAE’s CsLEOS real-time operating system will provide the foundation for the new capabilities as well as an open architecture for future enhancements.

The new system will give the C-17 full-authority fly-by-wire stability augmentation, stall protection, autopilot, flight director and ground proximity warning functions. Boeing says the upgrade will improve aircraft reliability, increase functionality and mitigate parts obsolescence issues.

The two new computers, major components of the existing electronic flight control system controls, will be installed on aircraft for deliveries beginning in mid-2005, including the most recent 60-plane Air Force order.

Even with a relatively new airframe, the C-17 cockpit technology is due some enhancements.

The C-17 is beginning to field a capability that will enable the Tanker Airlift Control Center (TACC) to send/receive data with individual airplanes, in-flight or on the ground.

The ability to operate within civil aviation is driving some programs. Several cockpit upgrades are planned and/or in work to keep the C-17 compliant with civil air traffic rules. The C-17 program office is currently certifying a controller-pilot data link capability and an aircraft dependent surveillance system for operational use.

Additionally, according to an AMC spokesperson, “Air Force Research Labs are investigating the possibility/concept of fusing various radar and imaging system inputs into a real-time, plain-view look at a runway environment, regardless of weather conditions, that allows pilots to safely deliver much-needed cargo.”

Longevity

A tribute to the technology capabilities of the aerospace industry and the aircraft management by the Air Force have created a flexible airlift fleet that set new standards during recent operational times and have raised the bar for the future just a little bit higher.