May 24, 2012: The U.S. Air Force recently retired its last C-130E transport. Over the last few years it has retired several C-130Es with over 30,000 hours in the air and over 45 years of service. One of those retired two years ago had spent 33,220 hours in the air and flew its last mission in Iraq, serving in a combat zone to the end.

Many of the C-130Es retired in the last few years had a few thousand hours left in them. These C-130s have undergone six or more refurbishments since they entered service in the 1960s. But these aircraft require more maintenance because of their age, which makes them more expensive to operate and less available for service than newer models.

The American C-130Es are not the ones with the most hours in the air. Several Canadian CC-130Es have over 50,000 hours. But these are to be retired soon. Even the Canadians found that, as their CC-130Es approached 50,000 hours in the air, maintenance became more expensive and time consuming.

On average, C-130s last about 25 years and about 20,000 hours in the air. But averages are just that, and some aircraft get lucky. If an aircraft has relatively few "high stress" (heavy load, rough weather) flights, it will fly longer. The key component in C-130 longevity is the center wing box. This component takes the most punishment, and if it suffers corrosion, as well as enough stress to cause metal fatigue, it usually means the useful life of the aircraft is much shorter.

The C-130 has been in service 53 years. So far, nearly 2,300 have been built and it is still in production. Most C-130 built are still in use, although that will change in the next decade as the large number built in the 1960s and early 70s retire.

Several other military aircraft remained in service over half a century (the British Canberra, U.S. B-52 and DC-3, the Russian Tu-95 and AN-2). But no other aircraft has remained in production for so long. In many respects, the C-130 is the heir to the 1930s era transport, the DC-3, which saw heavy use in World War II. Over a hundred heavily patched and rebuilt DC-3s continue to serve as working transports in obscure parts of the world, more than 60 years after they rolled off the production line.

Originally, the C-130 was designed to carry 15 tons of cargo, 92 troops, or 64 paratroopers. The latest version, the C-130J, has a top speed of 644 kilometers, a range of over 12,000 kilometers, and can carry 20 tons of cargo. The C-130 is used by more than 50 countries. Canada, the United States, and many other C-130 users are replacing their aging E models with C-130Js.

When retired, U.S. military aircraft usually end up at a storage yard in the dry southwest, where the aircraft can be cannibalized for spare parts until the remaining bits are sold for scrap. Those most recently put in storage are kept intact for as long as possible, so that they can be recalled to duty if there is a national emergency. The last U.S. C-130E is headed for the Air Force Flight Test Center Museum, where it will avoid scrapping and remain on display for decades more.