C-5 Service Life
The first C-5 Galaxy to be retired from the Air Force inventory was delivered 04 November 2003 to the Aerospace Maintenance and Regeneration Center at Davis-Monthan Air Force Base, AZ. Maintainers prepared the Lackland AFB, Texas-based aircraft for long-term storage. Thirteen C-5s from across the Air Force are scheduled to go to the center. Travis will retire up to four aircraft by the end of 2004, reducing the total number of assigned C-5s to 33.
The AF took delivery of the first C-5A in 1969. The force was then retrofitted with a new wing in the mid 1980s. With a projected structural service life of over 50,000 hours, the C-5 could last structurally well into the 21st century, depending on the model and other factors. However, system obsolescence, reliability and maintainability, operating cost, impacts of corrosion, and required repairs all factor in the service life of an aircraft.
The C-5 had the highest operating cost of any weapon system, and the trend was rising in tariff rates and reliability and maintainability costs for the C-5. The maintenance man hour per flying hour illustrates the difficulties in the C-5 force. The A models consumed 46.0 maintenance man hours per flying hour, 16.7 for the B model (CY96 data). With the retirement of the C-141 force, the C-5 took a larger role in peacetime movement of cargo. This meant mobility customers faced a more expensive option with the C-5. Depot levels decreased for the second consecutive year in FY96 to 18 percent of total aircraft. However, this was still above the planned 15.4 percent BAI level. The daily mission capable rate in the mid-1990s continued to improve. However, A-model MC rates averaged about 10.1 percent below the B-model. These problems raised concern for the economic life of the C-5A-model.
Cracks in the tail section of the C-5A cargo plane had the potential to ground the entire fleet of 76 A-model aircraft. The problem cropped up in January 1998, when the first C-5A undergoing periodic depot maintenance at Kelly Air Force Base, Texas, showed severe cracks in the horizontal stabilizer tie box, a key structural fitting that reinforces the wing-like structure to the 65-foot-tall tail. Immediate detailed inspections of all C-5As and later C-5Bs undergoing PDM at Robins and at the Lockheed Martin plant in Marietta, GA, revealed similar cracks in six of seven C-5As inspected.
The problem did not show up in the newer B models. After the first prototype verification, the C-5 Maintenance Directorate started the full tie box repair production run in September 1999, and complted seventeen aircraft by early 2001. The rest of the fleet was repaired at Lockheed Martin in Marietta, which concentrates only on the replacement and doesn't perform PDM.
Initiatives to replace avionics, engines and other equipment would increase the mission capable rate to 75 percent, and keep the aircraft in service through 2040. Air Force plans called for modernizing the 50 C-5Bs first, and then modernizing the 76 C-5As.
In December 2003 the four-phase C-5A Structural Risk Analysis and Model Revalidation study began at the request of Air Mobility Command. Warner Robins Air Logistics Center provided a quick look at the C-5's status, and AMC (officials) used that information to see if the C-5 was a good candidate for future investment and upgrades. If the tear-down analysis indicates that the plane is structurally sound, then they may consider it as a future investment. If not, they may be hard-pressed to invest more dollars.
Structural engineers, program managers and others from the strategic airlift and maintenance directorates here have been working fulltime examining the guts of the C-5 aircraft. The C-5, Tail No. 690004, is one of 14 aircraft Air Force officials selected for retirement. This particular C-5 was selected because of its true representation of the fleet.
Workers from the nondestructive inspection division of the maintenance directorate conducted the inspections, and results will be added to an existing model of the plane to compute how long it could continue flying. Although a majority of the tear-down part of the study did not take place until the third phase, some parts were removed to help the inspection and will be used as spare parts.
The study's four phases are:
Phase 1 -- Nondestructive inspection takes place here. Initial results are due to Air Mobility Command by February.
Phase 2 -- Planning and gathering of support equipment to tear down the plane. This phase runs through 2004. Components will be sent to an undetermined location later for further disassembly and inspection.
Phase 3 -- Tear down and further analysis.
Phase 4 -- Remaining parts of the aircraft will be disposed.
The C-5 cargo aircraft historically had been a poor performer in the reliability arena since its entry into the fleet in 1970. The transport edged close to AMC's standard mission capable rate of 75 percent, but its typical, nonsurge performance put it in the 65 percent range. If the huge airlifter could be made to work reliably and predictably, AMC officials say it would vastly improve scheduling and give a big boost to overall airlift capacity.
In FY04, the Air Force determined that 14 C-5A aircraft would be retired during FY04 and FY05. The eight aircraft retired in FY04 were T/N: 69-0004, 70-0458, 66-8307, 66-8306, 70-0450, 66-8304, 67-0171, and 67-0170. Aircraft 69-0004 was the first aircraft to be retired from the C-5 fleet and was delivered to Robins AFB on 21 October 2003 for an engineering teardown analysis with the remaining aircraft placed in excess status and stored at Aerospace Maintenance and Regeneration Center (AMARC) at Davis-Monthan AFB, Arizona. The Air Force determined that aircraft 70-0458 would be the first aircraft delivered to AMARC on 4 November 2003, with the remaining aircraft scheduled for input to AMARC at a rate of two per quarter.
The Air Force placed these aircraft in excess status at Davis-Monthan allowing the SPO to reclaim parts. Heavy use in the wars in Afghanistan and Iraq caused the transport aircraft to edge close to a severe parts shortage situation. Retired aircraft provided the SPO with a unique opportunity to reclaim parts and return them to Air Force supply inventory or direct ship parts to customers to fill MICAP requirement. The Air Force established a save list of 488 line items, thus over one thousand parts, valued at over $20M, could then be returned to AF inventory.
Aircraft stored at AMARC enabled the C-5 supply chain managers an exceptional opportunity to satisfy the war fighter's needs when no other source of supply proved available. When needed to support immediate needs for C-5 aircraft, WR-ALC materiel managers could request a priority parts removal from AMARC. During FY04, managers requested 136 priority removals to support the field units. Of these aircraft parts, 131 (96 percent) were directly shipped to field units to support OEF and OIF aircraft; the other five (four percent) were shipped to sources of repair for inspection, test, or overhaul prior to being shipped to the field. Technicians at AMARC removed 2059 parts from C-5s during FY04 and returned to the appropriate source of supply. The Air Force shipped 1058 parts directly to C-5 field units filling MICAP requisitions.
In FY04, the continuing need for C-5 aircraft in support of OEF and OIF required using all available parts resources. Using AMARC as a source of supply ensured C-5 availability during the largest troop movement seen since WWII. With these efforts, WR-ALC continued to provide support for the C-5 Galaxy and assist in meeting the mission goals of the USAF.
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