Roaring up the green canyon looking for the right ridge to mark a turn, the big Huey helicopter panicked knots of cattle and brought children tumbling out of their round, grass-roofed huts to stare and wave.

The soldiers, waving back in their camouflage fatigues, might have been Martians for all the wonder and uncertainty their arrival appeared to cause among the scattered residents.

But the commotion was just Col. William C. Comee Jr., commander of Joint Task Force Bravo, bringing some visitors out to see the latest phase of the more or less continuous U.S. war games in Honduras.

The crew was lost. "Can you communicate with that other aircraft?" Comee asked the pilot, meaning another helicopter full of Honduran officers. "Yes sir, but I don't speak Spanish," replied the pilot. The two choppers landed in a field, and the officers conferred in person about where to go next.

"Minimum support, remote areas and language difficulties all add realism" to the exercises, a U.S. Embassy description says.

This exercise, called Cabanas 85, ended formally Saturday with elaborate ceremonies at this sprawling wood-and-tin military base about 45 miles northwest of the capital, Tegucigalpa. In three months the soldiers on maneuvers built a two-lane, 13-mile gravel road between San Lorenzo and Jocon, about 65 miles northeast of Palmerola in Yoro province. Before this, there had only been cow paths for the area's desperately poor people.

U.S. and Honduran troops, taking the roles of guerrillas and guerrilla hunters, then parachuted and backpacked into the dusty fields and crept around in the trees for four days, digging foxholes and pretending to shoot each other.

In opening the arsenal of democracy to this impoverished Central American nation, the Reagan administration is "demonstrating U.S. resolve and willingness to support regional allies" against the leftist Sandinista government of neighboring Nicaragua, according to the official description.

The U.S. presence also is helping the Honduran government make itself felt in some of the country's most neglected and resentful areas -- courting hearts and minds with medical programs, roads to market, gifts and chewing gum -- and showing muscle to those disinclined to support the government.

Honduran troops swept much of Yoro province before the maneuvers began to make sure that no real guerrillas were around, even though none has been visibly active in Honduras since 1983. At least 20 persons were arrested and questioned, including an American Jesuit priest, the Rev. John Donald, who charged that Honduran officials threatened to torture him if he did not confess preaching communist revolution.

U.S. officials acknowledged that a GI drove the priest and three of his captors in a jeep to a camp in Jocon, where the new road ends and where Hondurans interrogated the priest. But the officials said that it was all a mistake by a couple of 18-year-old soldiers trying to be helpful to their Honduran counterparts and that the priest's charges of mistreatment are being investigated.

The exercises have been controversial since they began in July 1983, with congressional critics charging that U.S. forces are militarizing Honduras and establishing a permanent presence. At least $13 million has been spent at Palmerola and $8 million more at another base called La Ceiba.

From this dry highland valley, U.S. spy planes keep an eye on the guerrilla war in El Salvador, relaying information to the Salvadoran military chiefs. There are huge dishes elsewhere in Honduras that are presumed to listen to Nicaragua. But like all U.S. personnel here, Comee denies that the base has anything to do with the Nicaraguan rebels fighting the Sandinistas.

Comee, a compact, jovial Vietnam veteran, presents himself as part social worker and teacher to U.S. and Honduran troops, part hard-nosed soldier. He is at pains to point out how easily the wood CAT (Central American Tropical) huts will come down when Palmerola is no longer needed.

The huts resemble the bunk houses of summer camps, with plank walls and floors raised a foot off the ground. They shelter 1,100 troops and include several bars, a post exchange, a beauty shop for the 65 female soldiers and a field hospital right out of "M*A*S*H."

"People come in from all over to get treated," said Col. Joan Zatchuk, commander of the 85-member medical unit. "They think we're bringing in all of western medicine."

With a 12-bed capacity and one operating room, the unit admits only short-term patients. But it sends 22 medical teams into villages to pull teeth, examine cows and babies and give health lectures along with medicines.

"We talk to the kids and the teen-agers," said Zatchuk, who normally heads the eye, ear, nose and throat division at Walter Reed Army Hospital. She has been here six months. "You won't change the adults' habits," she said, but argued that health care will give people more hope for their futures and a stake in the status quo that could make them immune to revolutionaries.

At Camp Bulldog in Yoro, where the road is being built, Col. Paul Chenin, head of the engineering battalion from Fort Benning, Ga., said civic action is a major part of his job. He said the local ranchers were suspicious at first but softened when he made sure they were compensated for the road land, their downed fences and the blasting damage, which included a few dead cows and chickens.

The troops also give the unused parts of their C-rations -- now called "MRE," for meal, ready-to-eat -- to the civic action officer, who distributes them at a school or church. "We have avoided here having the people become beggars the way they did in Vietnam," Chenin said.

By early October, all the giant earth-moving machines at San Lorenzo are scheduled to be gone, along with the big trucks, the helicopters and the tents.

The 750 members of the engineering battalion will try to restore the rocky cow pasture of their camp to something resembling its original state before they go back to Georgia, said Chenin. The road will wash out before three years are up unless it is maintained by the government, and that is not likely, he added.

What is likely, although Chenin did not say so, is that the next set of exercises will extend the road farther into the wilderness and that the next set of Army engineers will keep it open awhile longer.

For Maria Santiago, the road makes little difference. The three-sided shack that is home for her, her husband and their five young children is one of three on an overlooking bluff. This extended family has been scraping a living from the rocky ground and helping ranchers set fences for 14 years, she said, and she has recently watched the huge machines arrive and carve out the road with detached amazement.

"No, it won't change anything for us," she said. "Why should it? I have nowhere to go."