What impresses onlookers most about the first fully modernized C-5M Super Galaxy strategic airlifter is not the twenty-two foot long, 300-pound, orange flight test instrumentation boom on the nose, though the structure is striking. It's not the new cargo compartment lighting, or the new auxiliary power units, or the nearly seventy other improvements made to the aircraft. The fact that most people who are not NBA players can stand upright in the cowlings of the new larger turbofan engines on the C-5M is certainly impressive. What first gets most people's attention is what comes out of the back of those powerplants — dramatically less noise.
The more than 500 US Air Force representatives, engineers, and long-time employees on the C-5 program present at the Lockheed Martin facility in Marietta, Georgia, on 19 June for first flight were the first to hear exactly how quiet the C-5M is on takeoff. The aircraft, flown by Air Force Lt. Col. Todd Markwald in the pilot's seat and Lockheed Martin test pilot Steve Knoblock in the co-pilot's seat, lifted off in approximately 3,200 feet, which happened to be right in front of the crowd. The giant transport that now fully meets the stringent Federal Aviation Regulation Part 36, Stage III requirements for reduced noise was almost out of earshot after it crossed the end of the 10,000-foot runway that Lockheed Martin and Dobbins ARB share.
"The first flight of this aircraft was basically a functional check flight tailored to safety-of-flight parameters," notes Knoblock. "We had to prove the aircraft was good enough to go into flight test." This C-5M, which is twenty years old, had been sitting on the ground for the past twenty months being modified. The first flight crew included flight engineers Air Force MSgt. Jeff Williams and Bill Lehto and Ron Bailey of Lockheed Martin and flight test engineers John Calin and Dave Shaw of Lockheed Martin. The crew landed at Dobbins after a 3.2-hour sortie over north Georgia and Alabama. Initial flightworthiness tests were later completed on 1 July.
This first C-5M (Air Force serial number 86-0013) is the product of two major modification programs, the C-5 Avionics Modernization Program, or AMP, and the C-5 Reliability Enhancement and Re-engining Program, or RERP. When a C-5 has been through both programs, it is re-designated C-5M. A total of 111 C-5A/B/C and now M-model aircraft are currently in the inventory, with 108 aircraft operational with active duty Air Force, Air National Guard, and Air Force Reserve Command units. The C-5 fleet has approximately sixty percent of its useful life left. The complementary modification programs are expected to extend the life of the C-5s until 2040.
AMP replaces the 1960s- and 1970s-era analog avionics system in the C-5 fleet with a commercially available digital suite along with an integrated architecture that allows for upgrades. It also incorporates an advanced embedded global positioning/inertial navigation system and improved communications equipment that adds satellite communications and a high-frequency datalink. These improvements ensure access to the global communications, navigation, and surveillance/air traffic management airspace, which essentially puts eight aircraft in the space now filled by two aircraft of any type. Noncompliant aircraft will be forced to take longer routes over the ocean, which, in the case of the C-5, means carrying more fuel and less cargo.
AMP began in 1999 with first flight of an AMP-modified C-5 occurring in December 2002. Kit installation began in 2004 at Dover AFB, Delaware, and followed later at Travis AFB, California. The Air Force completed operational test and evaluation of the AMP system this past June after more than 225 flights. Crews from Dover and Travis have been flying AMP aircraft operationally since 2005, including flying into Kuwait to support Operation Iraqi Freedom. They have logged more than 4,000 total flight hours.
The reliability enhancement portion of RERP makes up most of the modifications to the aircraft. Part of the enhancements replace out-of-production or historically unreliable components with updated ones, while others add structural strength. Every area of the aircraft is enhanced. RERP includes changes or modifications to the airframe structure (fifteen items), environmental and pneumatic systems (eight), hydraulic system (five), electrical system (two), fuel system (four), landing gear (seven), and flight controls (thirteen items). Four additional avionics system upgrades were shifted from AMP to RERP.
"Reliability enhancement is the big thing," notes Knoblock. "With the legacy aircraft, engine time on the wing averaged around 1,500 hours before some sort of maintenance would necessitate having to remove the engine. With the new engine, it should be about 10,000 flight hours before any maintenance requiring removal will be necessary." In addition, the new engine pylon, built by Goodrich, allows direct access to the line replaceable units inside the pylon and has easier-to-reach connections to the fuel and hydraulic lines.
The heart of the RERP program is the General Electric CF6-80C2L1F turbofan engine. The CF6 engine, which carries the military designation of F108, though it is seldom referred to that way, is nominally rated at 60,000 pounds of thrust but will be derated on the C-5M to 50,000 pounds of thrust. Even derated, these engines give the Super Galaxy twenty-two percent more thrust than the out-of-production TF-39 engines on the C-5A/B/C aircraft. This proven engine powers 229 commercial and military customers, including powering the VC-25s that transport the President of the United States.
More than 6,600 CF6 engines are in service, and the type has accumulated more than 288 million flight hours. As Knoblock noted, the engine is designed to stay on the C-5M for ten years without needing to be removed. The new engines will propel the C-5M with a 769,000-pound takeoff weight to 31,000 feet in just nineteen minutes on a hot day — better than the Air Force requirement to reach that height in twenty-five minutes. The current engines require thirty-three minutes to get the C-5A/B/C aircraft to 24,000 feet (at a takeoff weight less than 769,000 pounds).
Taken together, the two modernization efforts will see a wartime mission capable rate — the bottom line — for the C-5 fleet in excess of seventy-five percent assuming sufficient spares, an increase of more than fifteen percent over the current rate. The peacetime mission capable rate is expected to be in the mid-eighty percent range. AMP and RERP are expected to reduce operations and support costs by approximately $20 billion dollars in base year 2000 calculations, which means the program recoups its approximate $8 billion cost more than twice over during its service life. Most importantly, the Air Force will have an airlifter with greatly improved performance and payload capability.
"We had old-style analog devices in the C-5 before," notes Knoblock. "We relied on contacts and relays versus ones and zeros now. We had a lot of growing pains with those analog-to-digital interfaces in AMP. While involved, avionics test is relatively straightforward. With RERP, we have new engines, pylons, and structures, so we will need to get new loads and flutter data. Everything connected with the powerplants, including bleed air and the APUs, has to be tested. We will do a lot of specialized testing, such as testing flying qualities with an engine inoperative. The difference between AMP and RERP is sort of like the difference in making sure the TV and stereo are hooked up versus putting a new roof on your house. We have a lot of work to do in a short amount of time."
Three aircraft will be involved in the C-5 RERP test program, two C-5Bs and one C-5A. The two C-5Bs were the first aircraft to receive production AMP kits on the installation line at Dover AFB.
Work began on 86-0013, one of the C-5Bs, in October 2004, and the first engine run occurred in January 2006. This C-5M will be used primarily for flying qualities, flight performance, climatic testing, and performance envelope expansion.
Modifications on the second C-5B (86-0025) began in January 2005. The aircraft is expected to be flown by fourth quarter 2006. This C-5M will be used mostly for utilities and subsystem tests, airfield performance, and diagnostics testing. The distinctive nose instrumentation boom will be installed later. "This aircraft has a lot of bow wave," notes Knoblock. "The boom needs to be long enough to get in front of the bow wave into undisturbed air."
The lone C-5A model in the test program (69-0024) was the C-5A AMP test aircraft. RERP modifications began on it in September 2005. First flight for this aircraft is expected by early 2007. It will be used for human factors, technical order validation and verification, acoustics, and operations testing.
"A majority of the test program will be conducted in Marietta," Knoblock says. "Most of the test flights will last three or four hours, and the test plan calls for up to 1,000 test hours on approximately 200 flights. Testing requiring a large, long runway will be conducted at Edwards AFB, California. One such test involves 840,000-pound gross weight, and we can't do that in Marietta. The local area for a C-5 could be 1,000-mile radius. The test program is all-encompassing in terms of the flight envelope, payload, structure, and all the other systems."
Dynamic taxi testing, where the structural strength and flexibility of the new engines and pylons are tested over a variety of surfaces, was completed at the Air Force Flight Test Center at Edwards in August.
Under the current schedule, an RERP production go-ahead decision is expected by mid-2007. After a production gap of approximately one year between the end of test and the start of production kit installation, the RERP modification line should begin in Marietta in late 2008 or early 2009. Production will ramp up to twelve aircraft a year beginning with Lot 6, which, if the schedule holds, will go on contract for long-lead items in late 2010 with kit installation set to begin in 2013.
The newer C-5Bs will be modified first, with production Lots 1 through 6 covering the modification of thirty-eight C-5Bs. Lot 7 calls for the modification of the last nine C-5Bs, the first production C-5A and the two C-5Cs, which were specially modified in the late 1980s to carry spacecraft, and the first production C-5A. Lots 8 through 12 will be for modification of the other sixty C-5As. The last modified aircraft is scheduled to come off the Marietta modification line in 2020.
Jeff Rhodes is the associate editor of Code One.
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