One of the most familiar characteristics of the C-5 Galaxy, its pterodactyl-like screech, will be gone in the next decade, replaced by the familiar, and muted, call of the big aluminum birds that flock around commercial airports. Aircraft noise, however, is only one issue addressed by a large-scale, two-part effort to modernize the Air Force's entire Galaxy fleet.

“While mission reliability statistics are improving and are now at a ten-year high, the C-5 has suffered for a number of years from a low mission- capable rate,” says June Shrewsbury, the Strategic Airlift programs vice president for Lockheed Martin. “The C-5 modernization program is a comprehensive effort that will give the Air Force near-new fleet reliability.”

The first phase of the C-5 rejuvenation effort is the Avionics Modernization Program. Now midway through a seven-year development and production installation plan, AMP replaces the analog instruments and systems in the cockpit with digital displays and equipment. It also provides the necessary communications and navigational avionics to comply with Global Air Traffic Management, or GATM, a new set of international standards for aircraft movement and reduced separation in flight.

The objective of the Reliability Enhancement and Re-engining Program, the second and largest phase of the C-5 modernization effort, is to dramatically improve the overall dependability and maintainability of the fleet while reducing ownership costs. The centerpiece of RERP is replacing the C-5’s existing obsolescent engine with a current-generation turbofan.

“AMP will allow crews to fly unrestricted anywhere in the world,” notes Shrewsbury. “The Reliability Enhancement and Re-engining Program lets the crews fly at the altitudes required to access GATM-controlled airspace. However, the Air Force can’t implement RERP without AMP.”

Clear Distinctions

During the Civil War, Confederate Gen. Nathan Bedford Forrest said the key to victory was “to be first with the most.” The C-5 has proved that dictum since first gaining fame during Operation Nickel Grass, the massive airlift to Israel during the 1973 Yom Kippur War.

During Operation Desert Storm in 1991, C-5s were used to airlift 482,000 passengers and 513,000 tons of cargo every six weeks, an amount equivalent in ton-miles (moving one ton of cargo one mile) to the entire Berlin Airlift—a fifty-six week operation. C-5s comprised only twelve percent of the combined airlift fleet for Desert Storm but carried forty-four percent of all airlift cargo.

C-5 crews conducted twenty-nine percent of the flights to Afghanistan during Operation Enduring Freedom but carried nearly thirty-three percent of the passengers and forty-eight percent of the cargo. Preliminary statistics from Operation Iraqi Freedom show C-5 crews made twenty-three percent of the flights but again carried forty-eight percent of the cargo as well as eleven percent of the passengers (roughly 23,000) to the Middle East.

“The perception that the C-5 and the C-17 are interchangeable is completely inaccurate,” observes Shrewsbury. “The C-17 was intended to be a C-141 replacement. Both the C-5 and the C-17 have important, distinct roles in the Air Force’s strategic airlift mission. The Air Force has repeatedly made this distinction clear.”

That clarity can be supported with some simple measurements. The C-5, with its 34,795 cubic foot cargo hold, can carry twice what the C-17 can in nearly every important category of cargo—be it M1A1 tanks (two-to-one), M2/M3 Bradley Fighting Vehicles, Multiple Launch Rocket Systems (both four-to-two), AH-64 Apache helicopters (six-to-three), Patriot missile batteries (two-to-one, and two of the battery’s launch tubes have to be removed for it to fit in a C-17), and cargo pallets (thirty-six-to-eighteen). Maximum payload (261,000 pounds in the C-5 compares to 167,000 pounds in the C-17) is the only significant area where the numbers are not exactly two-to-one. However, a C-5 can carry a 167,000-pound load eighty-four percent farther unrefueled than a C-17.

“Having two fully operational fleets is in Air Mobility Command’s best interest because it prevents dependence on one type of airframe. If either fleet gets grounded, AMC still has a way to move oversized cargo,” notes Shrewsbury. “The bottom line is cost. For the cost of one new C-17, the Air Force can modernize three C-5s. AMC’s own analysis of alternatives shows that C-5 modernization remains the most cost-effective solution for reducing the airlift shortfall.”

Flying AMP

“I’m a pessimist by nature. I thought everything would fail and we would have to land right away. But we accomplished nearly everything we set out to do. We didn’t have to come back early because something didn’t work. We accomplished about twelve percent of the entire Block 1.1 test program on that first flight.”

That is how Wade Smith, the Air Force’s on-site chief engineer, describes the first flight of the first AMP test aircraft, which came on 21 December 2002. Smith, a civil servant who served as a flight test engineer on the milestone mission, is assigned to Detachment 4 of the Air Force Flight Test Center’s 418th Test Squadron, which, along with company flight test personnel and a detachment from the Air Force Operational Test and Evaluation Center, is organizing and implementing the AMP flight test program at the Lockheed Martin facility in Marietta, Georgia.

“The engineers had their hooks in the aircraft until late November, and then it was a race to fly before Christmas,” says Maj. Chris Dobb, the Detachment 4 commander. “But everything came together in the last few weeks. Ultimately, the first flight was very successful.”

Dobb and Lockheed Martin pilot Butch Johnston were at the controls of the modified C-5B during the five-hour flight, which came two months ahead of the planned program schedule. “I knew the aircraft, and Butch knew the avionics,” says Dobb, who has nearly 3,000 hours in the Galaxy. “We complemented each other well.”

Each of the flights in the AMP software Block 1.1 test program featured mixed Air Force and Lockheed Martin aircrews. The flight test engineers, who worked from laptop computers in the aircraft’s relief crew compartment to gather telemetry data, were also mixed.

The test program for Block 1.1, which was specifically limited in capability and provided the crew with the basic ability to aviate, navigate, and communicate, was completed on 7 March after ten flights and 44.8 flight hours. “The test program was very efficient,” recalls Dobb. “We had to repeat only a few test points.”

Hardware Is Easy

Getting to that first test flight wasn’t without challenges.

The Avionics Modernization Program began in 1999 when the Air Force selected a team led by Lockheed Martin. The approach is straightforward. Replace the 1960s- and ’70s-era type-specific analog avionics system currently in the C-5 with commercially available, late 1990s-era digital technology and develop an integrated architecture that allows for upgrades and is common with the commercial systems in use all over the world.

In the cockpit, the round-dial flight and engine instruments are replaced by seven Honeywell six-inch-by-eight-inch flat panel, liquid crystal displays, with six for the pilot and copilot and one on the flight engineer’s panel. These displays produce little heat, are fully readable in sunlight, and have been proved reliable in years of use on commercial airliners.

In the 1990s, the navigator on most C-5 missions was replaced by first-generation global positioning system navigational equipment. AMP will ensure even more precise navigation through a Honeywell embedded global positioning/inertial navigation system. Rockwell Collins multimode receivers provide a communications suite that adds satellite communications and a high-frequency datalink. Safety and crew situational awareness is increased by a ground proximity warning system and a collision avoidance system. Department of Defense-directed navigation requirements led to the early installation of the Honeywell Accelerated Traffic and Collision Avoidance System, which identifies other aircraft in the pilot’s vicinity and displays a conflict resolution, in the entire C-5 fleet. Lockheed Martin field teams completed the A-TCAS installations last October.

AMP has two basic requirements. The first is to make the Galaxy compliant with GATM, which, essentially, puts eight aircraft in the space now filled by two at altitudes above 29,000 feet. Noncompliant aircraft will be forced to take longer routes across the ocean, which means carrying more fuel and less cargo, which in turn means more trips to move the same amount of equipment or personnel. For a crew taking two tanks to the Middle East, that is a critical difference.

The second basic requirement is to increase reliability. The new equipment on the C-5 is predicted to improve reliability eight-fold.

Software Is A Little Harder

“Commercial-off-the-shelf is a myth,” Smith states bluntly. “A commercial airliner takes off, goes to altitude, cruises, descends, and lands. A commercial system is not designed to fly to altitude, descend and rendezvous with a tanker, descend, and ingress at 300 feet altitude. A flight management system for a commercial airliner could choke on that mission profile. We have a system with older parts that work, that is, the aircraft. What we are doing is adding some commercially available parts that we’re reasonably sure will work.”

“We had a lot of problems moving avionics from the lab to the aircraft,” recalls Dobb. “The transition was a bigger challenge than many people expected. The analog-to-digital equipment switch was sometimes tricky. The C-5’s stability augmentation system is a good example. The SAS controller was an analog system. Now it is a digital algorithm in the VIA [Versatile Integrated Avionics system; primarily the main avionics computer processor]. We didn’t know for sure it would work until we ran ground and flight tests. All of those kinds of changes have to be tailored in the software.”

To handle software and hardware integration issues, Lockheed Martin built a system integration laboratory that contains a hot mock-up unit with the VIA electronic boxes, the avionics interface units, and the cockpit displays. Company and Air Force pilots are using a simulator with a 200-degree visual system as a development tool, helping engineers to find and solve anomalies in the software as it is developed.

Software development has been broken into four major blocks. Block 1.1, which is complete, accounts for fifty-five percent of the required AMP source lines of code. Block 1.2, which covers another three percent, is in qualification testing. Block 1.2, which is scheduled to be flown by early summer, will be installed in a second test aircraft, a modified C-5A.

Block 2.1, which is now being integrated, will account for another thirty-three percent of the necessary code and will add the communications/navigation/surveillance software necessary for basic GATM compliance. Block 2.1 also adds new capabilities, such as making Category IIIA (bad weather) instrument landings. Flight testing of Block 2.1 is scheduled to begin in late summer.

A number of developmental items overlap AMP and RERP. As an example, capabilities that will be needed later specifically for RERP, such as an interface with the new engine’s full authority digital engine controller, are being included as part of the current AMP software development effort to lower total development costs.

The final nine percent of source code comes in Block 2.2, which is in unit test and should be ready for flight by the end of the year. Two further upgrades, which do not require as much development, will be used for verification testing (Block 2.2.1) and operational test and evaluation by the Air Force (Block 2.3). Verification testing is scheduled to begin in early 2004 and OT&E in the second quarter of next year. This testing will take place on a second modified B-model and the C-5A test aircraft.

Earlier this year, Lockheed Martin was awarded a $20.3 million contract for the first eight AMP production kits. Negotiations are under way for Lot 2, which could range from eighteen to thirty kits, depending on budget. Approximately two months are needed to modify each aircraft. AMP installations on the entire C-5 fleet are expected to be complete in 2007.

A Different Look

When AMP is complete, the makeup and location of the C-5 fleet will be dramatically different. Today, the Air Force has seventy-four C-5As; fifty newer C-5Bs; and two C-5Cs that are based at Travis AFB, California, that have had the rear troop deck removed in order to move satellites and other spacecraft from their manufacturers to launch sites. Active duty and Reserve Associate crews at Dover AFB, Delaware, and Travis fly both C-5As and C-5Bs. Air Force Reserve Command crews at Westover ARB, Massachusetts; the Kelly Annex of Lackland AFB, Texas; and Air National Guard crews at Stewart ANGB, New York, all fly C-5As. The C-5 training unit is located at Altus AFB, Oklahoma.

Over the next two years, fourteen C-5As, including the first eleven aircraft built, plus three other high-time air-craft will be retired. The other aircraft will be shuffled around, and C-5 operations will begin at three new bases at about the same time AMP concludes. The Air Force Reserve Command wing at Wright-Patterson AFB, Ohio, and the Air National Guard unit at Memphis International Airport, Tennessee, will trade their C-141s for ten C-5As each. The Air Guard unit at Martinsburg, West Virginia, will make a dramatic switch, getting eight C-5As for its C-130H-3s. In order to make all of these changes, sixteen aircraft each will be pulled from both Travis and Dover. The six aircraft at Altus will be transferred out, and the training unit will move from Altus to Lackland.

All of these planned changes will leave the Air Force with a fleet of 112 C-5s at eight bases by 2008, which is shortly before the C-5M aircraft, which is the designation for aircraft that have had both the AMP and RERP modifications, are scheduled to start showing up on flight lines.

The second R in the RERP acronym, re-engining, is actually a major factor in the success of the initial R and E part—Reliability Enhancement. The out-of-production General Electric TF-39 turbofans, the source of the C-5’s distinctive whine, will be replaced with a newer, more powerful, and currently in-production General Electric product, the CF6-80C2L1F turbofan that meets the Federal Air Regulation Part 36, Stage III requirements for low noise.

The new engine will have an impact on nearly every other major system and subsystem in the aircraft. The aircraft’s electrical system will be updated with a new engine-driven generator, pump, and a Sunstrand commercially available auxiliary power unit that will provide greater starting power.

With more than 3,100 engines in service, the CF6 engine family has accumulated more than 80 million flight hours on both commercial and military aircraft, including on Air Force One. Nominally rated at 60,000 pounds of thrust, the CF6s on the C-5Ms will be derated to 50,000 pounds each, which is still an additional 36,000 pounds, or twenty-two percent, more thrust for each aircraft. Not making the powerplants work to their full capacity extends maintenance periods, which, in turn, lowers ownership costs considerably.

“The warranties that come with the new engines mean the Air Force essentially gets a ten-year maintenance-free engine,” notes Shrewsbury. “The engines alone give the C-5 fleet at least a seventy-five percent mission-capable rate. Higher mean time between failures for the other RERP components will push the mission-capable rate into the low eighty percent range.”

The new engine requires a new pylon to attach it to the wing. The new pylon, built by Goodrich, is basically the same as the current design, only slightly narrower. The new design, however, allows direct access to the line replaceable units inside and easier fuel and hydraulic connections.

RERP also includes fifty-two improvements to the aircraft’s electrical, fuel, hydraulic, flight control, and environmental control systems as well as upgrades to the aircraft structure and landing gear. These enhancements range from replacing old components with new components to improving structural strength and installing technologically updated components.

The three aircraft modified for AMP testing will form the RERP test fleet. Modification work is scheduled to begin in September 2004, and first flight of a C-5M is scheduled for October 2005. The flight test program is expected to last until February 2007. At Air Force direction, the schedule currently has an eighteen-month gap between the completion of modifications to the test aircraft and the start of low-rate initial production of RERP kits in the second quarter of FY ’07, which differs greatly from how past major modification programs have been run. At rate production, modifying one aircraft will take approximately six months. If all 112 aircraft are converted, the last C-5M will come out of modification in 2018.

A Common Fleet

The C-5As were delivered between 1969 and 1975. The C-5Bs, which featured more than 100 changes from the A-models to improve reliability and service life, were delivered from 1985 to 1989. The C-5Bs have a higher utilization rate, so the difference in fleet average total flight hours has narrowed. On average, the A-models have approximately 18,000 flight hours per airframe, while the C-5Bs have been flown about 14,000 hours each.

“Concern about increased maintenance cost for the A-models is simply not justified,” says Shrewsbury. “The aircraft have some manufacturing and metal differences. However, hardware that was significantly different, such as the wings, is now the same. Also, the C-5As have received many of the structural enhancements that were designed into the C-5Bs. More items will be replaced in RERP. The two models are now close structurally. After RERP, they will be nearly identical.”

After the C-5 is modernized, the Air Force will have an airlifter that, with an 840,000-pound-gross takeoff weight and a 261,000-pound payload, can take off in less than 8,000 feet (thirty percent shorter than today). The modified airplane can climb to 31,000 feet (7,000 feet higher) in about twenty minutes (thirteen minutes faster) with a 261,000-pound load.

To put those numbers in practical terms, the C-5M will be able to carry 166 percent more cargo and passengers from Pope AFB, North Carolina (next door to Fort Bragg and the 82nd Airborne Division), nonstop to Ramstein AB, Germany; or 332 percent more payload from Travis to Yokota AB, Japan, on any given flight. This means less cargo left in the marshalling yard and fewer missions to move the required cargo—the first with the most. And the aircraft that will be used to move the cargo and people will be much more reliable.

“C-5M will give the same life expectancy for the A- or B-models. Because of some forward thinking by its original designers, we have no corrosion problems,” Shrewsbury concludes. “The fleet can go to 50,000 hours or to about 2040. We are confident that the C-5M will get us there.”

Jeff Rhodes is the associate editor of Code One.