lost his hand to the propeller. Another downside of the PACV was the degree of maintenance it required: each hour of operation required 20 hours of maintenance, double the 10-hour average for contemporary military helicopters. An Army evaluation found that the PACV had an operationally ready rate of 55.7 percent, and all three Army ACVs were only operational during June 1969. This maintenance requirement, which was made even worse when the vehicles suffered damage, combined with the insufficient firepower to lead an Army evaluation to conclude that "there is no hope of the [PACV/ACV] unit fighting to a satisfactory conclusion in any large engagement." The PACV was also very expensive, costing about $1 million each, as much as 13 Patrol Boat, Rivers. Because of their high profile and degree of threat, the PACVs and ACVs in Vietnam became major targets. The Viet Cong used ambushes and naval mines against the PACVs. Mines proved especially effective: Army ACV 902 was destroyed by a tripwire-triggered mine on 9 January 1970. Though no one onboard was killed, 14 men were injured and the attack slowed the pace of ACV operations because of Army regulations stipulating that the hovercraft work in pairs to protect each other. When ACV 901 was destroyed by a command-detonated mine on 3 August 1970, killing three, the ACVs were deactivated. The 39th ACV Platoon ceased operations on 31 August 1970 and officially left Vietnam in September, transferring their sole surviving ACV to the Army Transportation Museum in Virginia. Navy PACVs returned to the continental United States that August as well. In total, Navy PACVs saw more than 4,500 hours of operation. Postwar US Coast Guard service Following their withdrawal in 1970, the Navy PACVs were transferred to the U.S. Coast Guard for evaluation. The Coast Guard used PACVs, which they called Air Cushion Vehicles (ACVs), through 1975, when they cancelled the ACV program due to budget constraints. Two were stationed at Fort Point, San Francisco and the third was used for Arctic Trials in Point Barrow, Alaska, though they were also tested in the Great Lakes and Chesapeake Bay. The Coast Guard PACVs were modified to meet their requirements by replacing the .50 cal gun mount with an observation dome and adding a KAAR LN66 radar and search-and-rescue equipment. Coast Guard PACVs were crewed by 3—operator, radar operator and navigator, and search-and-rescue crewman—and could carry 6 passengers and half