May 3, 2006: Since it was first introduced 22 years ago, U.S. Army AH-64 Apache helicopter gunships have flown some two million hours. About twenty percent of that has been in the new, and very popular, AH-64D "longbow" version (equipped with sensors and electronics making it very capable at night). Some 35 percent of all hours have been flown since September 11, 2001. The AH-64 fleet now stands at about 730 aircraft. Up to a third of them have been in Iraq at any one time. The AH-64 has proved very effective, and is in great demand for combat support and convoy escort. Because of the war, the AH-64s are operating at over five times the rate (hours flown per year) they would in peace time. This has caused a major problem with providing sufficient maintenance. Much of the work is being turned over to civilians, at least when possible. But the spare parts expenses are huge, and the manufacturers have been under pressure to keep up with demand.