Once again, the Pentagon seems to be saddled with an expensive weapons system that does not work the way it should. Once again, high-tech seems to translate into low performance for the military.

This time it is the U.S. Army's AH-64 Apache attack helicopter, already stationed in the Persian Gulf and considered the premier weapon against Iraq's thousands of tanks. If U.S. forces and others have to depend on the Apache, they may find themselves in serious trouble.The Apache, costing about $14.6 million per aircraft, was designed for high-intensity battle, day or night, in adverse weather conditions. It is supposed to find tanks and other targets and destroy them with an arsenal of laser-guided missiles, 30 mm cannon and 2.75-inch rockets.

Yet according to a General Accounting Office study - the GAO is a congressional agency - the Apache has trouble staying in the air even in peacetime conditions.

The Apache can only fly about two and one-half hours without essential and complex maintenance work. There aren't enough mechanics to keep the helicopters flying. As a result, the Army can't even meet its peacetime goal of having 70 percent of the helicopters available to perform missions. It won't say what the percentage level is, but admits it falls "far short" of 70 percent.

The GAO says it is doubtful the Apache can meet the far more strenuous demands that come with high-intensity combat.

When used in the Panama invasion, the Apache failed repeatedly while trying to support ground troops in that country's high humidity. In the Middle East, the Army has had to cancel night-time maneuvers after a series of accidents caused by sand blowing into the rotors. So much for the day-night, all-weather Apache.

The Army says it plans to increase the number of mechanics in Apache battalions so that maintenance can be done faster. And it will look to Apache contractors for more repair facilities and personnel.

Somehow, that doesn't seem to solve the basic problem. Instead of more mechanics, the Army needs a better attack helicopter - one that can fly for more than two hours before breaking down.