To upgrade cargo carrying capacity, MAC initiated a major upgrade program for its C-141A fleet beginning in 1979. The project added an inflight refueling system and 23 feet in length to the fuselage. The "stretched" "Starlifter" was designated the C-141B. The first C-141B was received by the Air Force in December 1979. Conversion of 270 C-141s from A to B models was completed in 1982.
The C-141B is a stretched C-141A with in-flight refueling capability. Stretching of the Starlifter consisted of lengthening the plane 23 feet, 4 inches (53.3 centimeters), which increased cargo capacity by about one-third - 2,171 extra cubic feet (65.13 extra cubic meters). Lengthening of the aircraft had the same effect as increasing the number of aircraft by 30 percent. The C-141 was the first jet aircraft designed to meet military standards as a troop and cargo carrier.
A universal air refueling receptacle on the C-141B transfers 23,592 gallons (89,649.6 liters) of fuel in about 26 minutes, allowing longer non-stop flights and fewer fuel stops during worldwide airlift missions. The C-141 force, nearing seven million flying hours, has a proven reliability and long-range capability.
The Starlifter, operated by the Air Mobility Command, can airlift combat forces, equipment and supplies, and deliver them on the ground or by airdrop, using paratroop doors on each side and a rear loading ramp. It can be used for low-altitude delivery of paratroops and equipment, and high-altitude delivery of paratroops. It can also airdrop equipment and supplies using the container delivery system. It is the first aircraft designed to be compatible with the 463L Material Handling System, which permits off-loading 68,000 pounds (30,600 kilograms) of cargo, refueling and reloading a full load, all in less than an hour.
The C-141 has an all-weather landing system, pressurized cabin and crew station. Its cargo compartment can easily be modified to perform around 30 different missions. About 200 troops or 155 fully equipped paratroops can sit in canvas side-facing seats, or 166 troops in rear-facing airline seats. Rollers in the aircraft floor allow quick and easy cargo pallet loading. A palletized lavatory and galley can be installed quickly to accommodate passengers, and when palletized cargo is not being carried, the rollers can be turned over to leave a smooth, flat surface for loading vehicles.
In its aeromedical evacuation role, the Starlifter can carry about 103 litter patients, 113 ambulatory patients or a combination of the two. It provides rapid transfer of the sick and wounded from remote areas overseas to hospitals in the United States.
During Desert Shield and Desert Storm, a C-141 from the 437th Military Airlift Wing, Charleston AFB, S.C., was the first American aircraft into Saudi Arabia, transporting an Airlift Control Element from the 438th Military Airlift Wing, McGuire Air Force Base, N.J. In the following year, the C-141 completed the most airlift missions - 7,047 out of 15,800 - supporting the Gulf War. It also carried more than 41,400 passengers and 139,600 tons (125,690 metric tons) of cargo.
The first Air National Guard and Air Force Reserve units to receive the C-141 as unit equipment became operational in fiscal 1987. The units are located at Jackson, Miss., and Andrews Air Force Base, Md. The Air Force Reserve, through its associate units, provides 50 percent of the Starlifter's airlift crews, 40 percent of its maintenance capability and flies more than 30 percent of Air Mobility Command's peacetime worldwide missions.
In the 1990s the C-141 went through a series of major repairs. Wing Station 405, windshield post crack repairs and center wing box repair/replacement are complete.
Specialists realized during the continuing Aircraft Structural Integrity Program (ASIP) that the wings of the C-141 aircraft faced the risk of catastrophic failure that increased at an alarming rate. Cracks in the wing lower surface skin panel at the pylon attachment "E" points represented a known risk. The cracks occurred because of stress centered in the wing panel as a result of the stretch modification performed at the depot during the 1970s. Nondestructive Inspections (NDI), a process refined to provide a more reliable inspection that detects smaller cracks, helped to maintain the risk at an acceptable level. Indeed, maintenance workers performed Home Station Checks (HSC) at the using Commands, inspecting wing panels every 120 days at Air Mobility Command (AMC), the Air National Guard (ANG), and Air Force Reserve Command (AFRC) units, and every 30 days at Air Education and Training Command (AETC) units. The HSC required an extra down day for each aircraft. Detecting a crack meant the aircraft would be removed from service until it could be repaired. The aircraft was repaired using a kit that consisted of approximately 70 structural parts and fasteners.
One of the main structural members in the C-141 fuselage, the FS988 frame also includes the point at which the main landing gear connects. Inspections performed in the mid-1980s revealed cracks in the 998 main frames, which were replaced when they were found cracked. As periodic inspections were performed, center maintenance personnel discovered that the cracked frames were happening more often. In January 1995, Center officials decided to replace these frames on 96 aircraft during PDM at Robins and at the contract facility. As the number of cracks discovered increased, LJ engineers called for the replacement of the 998 frames in all core aircraft before the end of 1999. Experts agreed that the task could not be accomplished in the allotted time during PDM only. The Air Force selected CTAS to perform the maintenance, but the first of the aircraft would have to be placed in contract status before CTAS could start manufacturing tooling.
As the aircraft continues to age, it is quite possible new structural problems may limit the readiness of the force. To slow aircraft aging of the active duty fleet, 56 PAI aircraft have been transferred to the UE Guard and Reserve as of FY95. Additionally, the process of retiring high flight hour equivalent aircraft will culminate with the retirement of the entire AMC active duty fleet by FY03.
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