Bullet-riddled, sand-scarred choppers in various stages of surgery cram the depot's cavernous hangars. Roughly 3,500 workers buzz around yellow metal repair stands, working feverishly to get wounded machines fit to return to combat.

"You've been awfully busy here," Gen. Richard Cody, the Army's vice chief of staff and one of its most experienced combat helicopter pilots, told engineers and mechanics at what insiders call "See-cad" - from the acronym CCAD - during a visit this year.

Busy as they are, neither the Corpus Christi depot nor the Army's four other maintenance depots, which repair and rebuild everything from tanks to handguns, are anywhere near catching up with the phenomenal wear and tear on equipment caused by wars that have lasted far longer than the military expected.

"We were talking war fights of 30 to 60 days, and here we are a few years later," said Gary Motsek, director of support operations for the U.S. Army Materiel Command at Fort Belvoir, Va.

Moreover, Motsek said, while troops in Iraq and Afghanistan continue to get the equipment they need, it will take years - and billions of dollars - for the services to recover.

"If combat operations and hostilities ended tomorrow - just suddenly ended - it's going to take the Army two more (years) to complete the work that needs to be done," Motsek said.

The Army's other depots, including Red River Army Depot at Texarkana, have been just as busy as Corpus Christi. Since 2001, the five have repaired or rebuilt more than 1,700 tracked vehicles, 9,600 Humvees, 7,200 other trucks and 100,000 small arms, from 9 mm pistols to .50-caliber machine guns, Motsek said.

The costs are hard to pinpoint, for they fall under several budgets. The Congressional Budget Office estimated last spring that by Sept. 30 the Pentagon would have spent $13 billion to $18 billion on war-damaged equipment.

The list of equipment damaged or worn out in Iraq or Afghanistan is enormous, said Daniel Goure, a military analyst with the Lexington Institute, a think tank partly funded by defense companies.

"We are talking about backlogs of tens of thousands of pieces of equipment, ranging from tanks to mobile kitchens, repair vans to counterbattery radars," Goure said. "It's a huge problem."

That has contributed to shortages of some items, such as trucks and attack helicopters, among units in the United States - especially the National Guard and Army Reserve, Motsek said.

Guard and other units have been ordered to leave combat equipment such as armored Humvees in Iraq when they come home. New gear is provided first to units on their way to the war.

A bipartisan group of more than 40 senators wrote President Bush a letter on Nov. 3 urging him to include enough money in next year's budget to "bring our Guard up to 100 percent of key assets."

Nationwide, the senators said, the Guard has only two-thirds of the Humvees, three-fourths of the radios, half the night vision devices and a fourth of the medium trucks it needs.

"The greatly diminished percentage of equipment on-hand in our Guard units carries with it the risk of not only denying these units the equipment needed to conduct good training for their combat mission but also leaves them with fewer tools to support state responses to natural disasters, terrorist incidents or other emergencies," they wrote.

One source of the problem is the unexpected intensity of the war in Iraq, where 160,000 U.S. troops still fight a stubborn insurgency more than two years after President Bush declared "major combat" over.

"We're flying about five years' op tempo (operating time) in one year on some airframes," Cody said in an interview during his Corpus Christi visit.

The CBO study said Army and Marine Corps trucks in Iraq and Afghanistan "are being driven roughly 10 times more miles per year than has been the average over the last several years." Combat vehicles such as tanks and Humvees are logging five times more use than normal, it said.

"Afghanistan and Iraq are two of the harshest environments where you can put rotorcraft," said Cody, whose commands have included the 160th Special Operations Aviation Regiment and the 101st Airborne Division.

In arid Afghanistan, much of the soil resembles "moon dust," he said. The fine, powdery sand seeps into every nook and cranny of machinery and engines, quickly degrading them. Engines have to be torn down and rebuilt to get it out.

"In Iraq, you have the heat, and you've got the desert, and you've got the sand," Cody said. "Operating aircraft - especially turbine aircraft with rotor blades - in that kind of environment adds a wear and tear, especially the way we use those aircraft."

Among the tasks being performed at Corpus Christi, for instance, is chipping thin coats of glass off of helicopter engine turbine blades. The turbines suck in sand with the air that feeds their compressors. The heat inside turns the sand into glass.

"These engines burn at about 860 degrees centigrade (1,580 degrees Fahrenheit)," Cody said. "Over time, your (turbine) rotors get glazed with this glassy formation and it robs the turbine of its power output."

Walt Butsch, a Corpus Christi Army Depot engineer who volunteered for 120 days in Iraq doing helicopter maintenance, told Cody he spent much of it patching rotor blades. "Lots of bullet holes," he reported.

"The problem is, the up-armored vehicles didn't have, in most cases, the engine, shock absorbers, drive trains, suspension - any of that - for the extra weight," Goure said. "So that's going to wear out at a faster rate. The engine that was going to go 100,000 miles is going to go half of that."

The Army owns about 4,000 helicopters and more than 600 are in Afghanistan and Iraq, Cody said. They include AH-64D Longbow Apache attack choppers, OH-58D Kiowa Warriors, and UH-60 Black Hawk and CH-47 Chinook transports.

Much maintenance is done in the field by crew chiefs and mechanics. Some is done at one of 13 Special Test Inspection and Repair stations, including 11 in the continental United States, one in Hawaii and one in Germany.

But after a certain amount of wear or damage, Army helicopters - and many from other services - come to Corpus Christi for "recapping," meaning they are pulled apart and rebuilt from the ground up.

As he toured the facility, asking questions like the former helicopter maintenance officer he is, Cody reminded the workers that he has a selfish reason for keeping an eye on what they do. His two sons, both Army captains, fly Apaches in his old division, the 101st Airborne.

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