The Army's Apache antitank helicopter, a mainstay of U.S. forces deployed to Saudi Arabia, needs repairs after an average 2 1/2 hours in the air during peacetime and may be useless in war, congressional investigators have reported.

The Apache is equipped with see-in-the-dark electronics, 30mm cannon, guided missiles and rockets. But its maintenance needs are so complex the Army should concentrate on beefing up the Apache's maintenance crews instead of buying more of the helicopters, the report said. The Army wants to purchase 66 more Apaches, bringing its fleet to 807.

In a report Friday, the General Accounting Office said the Army has too few Apache mechanics. About 100 maintenance personnel assigned to an Apache battalion take care of 39 helicopters, including 18 Apaches. The Marine Corps, however, achieves far more flying hours with 225 technicians taking care of 24 simpler helicopters.

The GAO report found no change from an earlier agency conclusion that Apaches were "fully mission capable" only about half the time, far short of the Army's 70 percent goal.

"Given that the Apache has not been able to attain availability goals in peacetime despite favorable conditions, it is questionable whether it can meet the far more strenuous demands of high-intensity combat," the GAO said in the report.

The GAO said the aircraft's electronics fault-detection system erroneously reports faults about 40 percent of the time.

In addition, soldiers maintaining the Apache spend only about 30 percent of their time repairing the aircraft, devoting the rest of their time to guard duty, physical training, motor pool detail, marksmanship testing and other tasks. For this reason, reenlistment rates are low and experienced mechanics rare in Apache battalions.

Components fail at rates far higher than expected when the aircraft was designed -- for instance, the main rotors must be replaced every 164 hours instead of lasting 1,500 hours, GAO said.

According to the GAO, the Army's commander in Europe has said "as much as 50 percent of the time Apaches spend in the hangars for maintenance is devoted to troubleshooting and that this time was increasing."

In an Aug. 31 letter to the GAO, David J. Berteau, principal deputy assistant secretary of defense for production and logistics, said the agency's findings "mostly portray the readiness and support problems of the Apache helicopter of about 18-24 months ago and were not new to the Army."

Maj. Nancy Burt said Friday that the Army and McDonnell Douglas had identified 173 problems, resolved 106 and are fixing 67.

Burt also said that Apaches sent to the Persian Gulf have exceeded the service's goals for capability.