His critics in Congress and the military keep looking for hidden motives behind Rep. Larry J. Hopkins's one-man crusade to kill the Army's top budgetary priority for the fiscal 1991 budget, a new, high-tech light attack helicopter known as the "LH." They wonder why a moderate-to-conservative pro-defense Kentucky Republican who served in the Marine Corps should be so hostile to something the military wants so badly.

Hopkins insists his adversaries are overlooking the obvious. "My goal is to save the American taxpayers $42 billion," he said. "We can do that by keeping the pickup trucks and getting rid of the Ferrari. I don't want to whittle a little bit. I want to chop down the whole tree."

That view has put Hopkins in the thick of one of the congressional battles swirling around the fiscal 1991 defense budget -- the "battle of the choppers," in which the nation's four helicopter companies are struggling to preserve existing programs while pressing for new ones. At stake is the possible survival of one or more of the companies, the well-being of dozens of subcontractors, the jobs of thousands of workers and the economic health of whole communities.

The helicopter controversy is like other disputes involving ammunition plants, home ports and ships that will be mediated by the four main defense committees in coming months. As the discussion moves forward, issues of grand military strategy quickly become tangled in more parochial concerns.

At the center of this controversy is an Army decision to invest most of its aviation money in the 1990s in development, testing and purchase of one advanced aircraft, the LH.

The nation's four helicopter companies have formed two teams that are seeking the lucrative LH contract, pitting McDonnell Douglas Helicopters and Bell Helicopter Textron against Boeing Vertol and Sikorsky Aircraft of United Technologies Corp. If Congress goes ahead with the program, next January the Pentagon is scheduled to select one of the competing teams to build up to 2,096 of the helicopters.

But the LH plan, now under top-level Pentagon review, is meeting mounting resistance from congressional backers of two existing helicopter programs that the Army is ready to sacrifice.

One is the AH-64A Apache, produced by McDonnell Douglas in Mesa, Ariz., with the help of subcontractors in all but eight states. The other is the Army Helicopter Improvement Program (AHIP), in which Bell Textron -- McDonnell Douglas's partner in the LH competition -- is rebuilding and modernizing older OH-58 light attack helicopters in Abilene, Tex.

The fate of the LH also may be indirectly linked to that of another futuristic aircraft with impressive congressional support: the V-22 tilt-rotor being developed for the Marine Corps by Bell Textron in Fort Worth and by Boeing Vertol outside Philadelphia. Though the V-22's long-hauling mission differs from the LH's attack role, some skeptics question whether the country can afford to develop two such expensive machines simultaneously. The cost of the V-22 program is estimated at $28.5 billion.

The helicopter battle mirrors the larger defense debate in several ways.

While Defense Department planners emphasize long-range technological development in leaner budgetary times, a sizable congressional bloc favors upgrading exist- ing weapons systems, such as Apache, which provide jobs and contracts now, not in the distant future.

Congress's recent record on helicopters also shows its aversion to killing any program outright. Last year it restored funds for both AHIP and V-22 that had been cut by the administration.

The committee system provides numerous openings for program defenders. Last year, for example, the Senate Armed Services Committee defeated an attempt to add money for "advanced procurement" of Apache helicopters that the administration did not want. But the Senate Appropriations Committee, responding to a "must have" request by member Dennis DeConcini (D-Ariz.), added $1 billion for Apache procurement to a House version of the spending bill. Ultimately, Congress appropriated double what had been requested for Apaches in the fiscal 1990 budget.

Congress did agree to add language to end further funding of Apache and AHIP modernization of the OH-58, in the budget for fiscal 1991, which begins Oct. 1. But supporters of the aircraft are now rallying to reverse that action, and to provide a new round of funding for the V-22.

Rep. Dave McCurdy (D-Okla.), a member of the House Armed Services Committee, has emerged as the chief House advocate of the LH as head of the informal "Army Caucus," whose members mostly have Army backgrounds or Army bases in their districts.

McCurdy started the caucus three years ago to balance the

overwhelming congressional support for Air Force and Navy programs. The Army needs more help than ever this year because its forces are most heavily affected by the coming U.S. military pullback from Europe.

McCurdy and the Army are making their stand on the LH. While acknowledging that the program had a rocky beginning, McCurdy said the Army has settled on a clear role for the craft as a night-fighting vehicle using composite structural materials and a special engine to reduce its visibility to radar and infrared sensors.

The program has backing from Rep. William L. Dickinson (R-Ala.), the ranking Republican on Armed Services whose district includes Fort Rucker, the Army's helicopter center. But Dickinson, sometimes nicknamed "The Godfather of Army Aviation," also wants continued funding for AHIP, which is also a light attack craft.

Technical problems still bedevil the LH program and the cost deters even some hawks.

"I don't think we need it right now," said another powerful member of the Armed Services panel, Rep. G.V. "Sonny" Montgomery (D-Miss.).

Instead, he would prefer that the Army continue production of the Apache, a heavy attack aircraft. On the face of it, that case seems to face tough going. Congress last year provided what was supposed to be a "final" $1.4 billion to pay for another 132 craft, rounding out the Army total at 807, well short of earlier Army requests for 975. Moreover, the rationale for continued production of a heavy attack helicopter, whose main mission was to destroy Warsaw Pact tanks, appears weakened by recent events in Europe.

But the Apache is protected by a formidable tribe of congressional warriors, including both Arizona senators -- DeConcini and Republican John McCain, Sen. Alan J. Dixon (D-Ill.), Rep. Nicholas Mavroules (D-Mass.) and Montgomery.

McCain and DeConcini -- who serve on the Armed Services and Appropriations committees, respectively -- want to protect McDonnell Douglas Helicopter jobs in Mesa. Dixon has a broader interest in the company's overall health because thousands of his southern Illinois constituents work at McDonnell Douglas Aircraft's St. Louis plant.

Montgomery, a close friend of President Bush and key member of the House Armed Services Committee, wants more Apaches for units of the National Guard, his favorite cause. Mavroules, who chairs a key subcommittee on Armed Services, represents Lynn, Mass., where General Electric makes the Apache engine.

Apache proponents note that the aircraft performed well during the invasion of Panama last December and remains the world's most effective helicopter against tanks in medium-intensity conflicts. If outfitted with a new "fire-and-forget" attack system called Longbow, they say, Apache could go on for years.

The situation has McDonnell Douglas lobbyists doing a straddling act on the Hill, sources say. The company could prosper if its team is picked to produce LH, but it would also like to keep the Apache assembly line rolling. It reportedly has been supporting a scheme on the Hill to add $18 million in "advanced procurement" money for Apache this year.

The company would neither confirm nor deny a report that Maj. Gen. Ronald K. Andreson, who directs the LH program for the Army, had called top company officials to complain that lobbying by McDonnell Douglas's Joseph S. Kimmitt was undermining the LH. Kimmitt, a highly decorated retired Army officer and former secretary of the Senate, did not return a

call.

Meanwhile, AHIP and V-22 have formidable congressional backing.

"It works," said Rep. Marvin Leath (D-Tex.), whose floor amendment to add AHIP funding passed on a voice vote last year. Leath, a senior member of the Armed Services Committee, favors cannibalizing the LH technology and engine for use in AHIP and other systems.

Rep. Curt Weldon (R-Pa.), chief House ball-carrier for the V-22 -- a key hope for the Boeing Vertol plant outside Philadelphia -- is ecstatic over the outlook. "There's no member of Congress who's arguing against V-22 -- and that's not true of Apache, LH or AHIP," he said.

Some observers say that Sikorsky, which is teamed with Boeing Vertol in the LH competition, has the most to lose if the program is canceled.

Bell and Boeing already have the contract for the V-22, which is much further along in development than the LH. McDonnell Douglas produces the Apache, which could enjoy a long life if the LH is killed. But Sikorsky, with about 12,000 employees in its Connecticut helicopter works, would face an uncertain future in the late 1990s without the LH as orders for its UH-60 Blackhawk utility helicopters trail off.

Hopkins has not made clear which mix of existing helicopter programs and upgrades he would support in place of the LH if he succeeds later this year in passing an amendment to deny research funding for the program. Instead, he has tried to focus attention on the cost of the program at a time of growing budget pressure on the military.

"Nobody needs to tell you what it's like when that fraternity {of contractors and congressmen} goes to work," growled Hopkins, who has himself pulled in thousands of dollars in speaking fees from defense contractors, including $2,000 in 1988 from McDonnell Douglas Helicopters while serving on the House Armed Services Committee. "We can't afford to support the oink-oink boys of the U.S. Congress. Pigs get fat . . . but hogs get slaughtered."