Jeff Bellistri wants to fly jets. But the Navy's theory is that men who snort cocaine shouldn't be allowed in uniform, let alone in jets. To that end, 107 students from the U.S. Naval Academy here were hauled from their bunks one morning last November and ordered to produce urine samples. When the results came back, Bellistri was accused of using cocaine.

Bellistri says he never touched the stuff. If someone had used it around him, he says, he would have walked from the room. That is what the academy recommends. But the academy didn't believe him and last week he was kicked out. Now he can be found wearing corduroys instead of smart military dress, cleaning a car in his parents' driveway, and proclaiming his innocence.

The Navy argues that the urine test, which found 16 times the acceptable level of a cocaine-related substance in Bellistri's sample, was accurate. Bellistri says he knows something went wrong with the testing, because he never took cocaine: He just can't prove it.

Drug-testing by urinalysis is controversial, especially with its increasing use by private companies and recent plans to test civilian government workers. This week, Maryland State Police announced plans to give urine tests to troopers, while a federal judge temporarily barred the Potomac Electric Power Co. from implementing sweeping new drug-testing rules.

While critics frequently protest that civilian drug-testing programs are an invasion of privacy, courts have decided that the military can conduct widespread urine testing as long as it is random. Today the only way a military person can challenge a drug test is on grounds that it was not given randomly, was inaccurate or that the drug was unwittingly consumed.

A Naval Academy report made after Bellistri's first hearing acknowledged that "proper procedures were not followed with some midshipmen" during the Nov. 12 sweep, which at the time was the largest the academy had conducted. Two midshipmen who acted as observers contradicted statements by their supervisors and said people had "access" to the open sample boxes.

The report said that some midshipmen were allowed to urinate without observers present, and that some sample boxes -- although apparently not Bellistri's -- were not placed in sealed cartons when they were stored in an office overnight before being shipped to Norfolk by Federal Express. The report also said it was later learned that the locked office could be opened easily with a credit card.

Despite these security lapses, the report concluded that there was no evidence the seals had been removed and said there was "no significant possibility that Midshipman Bellistri's urine sample was tampered with." If there were any doubts, Navy officials stated, the case would have been resolved in Bellistri's favor.

"The odds are against me, but I'm not bitter or mad at the academy," said Bellistri, 23. "It's their urinalysis program and they are standing by it. As far as they are concerned, there were no mistakes."

Bellistri, who lives in Severna Park, Md., has had several hearings since the test came back positive in mid-November. At the first, the hearing officer decided he had used cocaine. At the second, another hearing officer recommended that the academy superintendent expel him. Then last week, the superintendent recommended to Navy Secretary John F. Lehman Jr. that Bellistri be dismissed from the Navy. Bellistri was ordered out of the academy and out of uniform until Lehman's decision, expected in the next 10 days.

Meanwhile, thanks largely to telephone calls and letters from Bellistri and his parents, the controversy over his urine sample has become a "media event."

In the last few weeks the Naval Academy had a highly unusual press conference to bolster evidence of Bellistri's guilt. The urine test was a surprise, Navy officials said, giving no chance for preplanned practical jokes or sample-switching -- and no warning to Bellistri that he should abstain from drugs. The high level of a cocaine-related chemical in his urine, they said, showed he could not have ingested it accidentally.

"We have no doubt that there was, in fact, cocaine present in the sample of urine," said academy spokesman Lt. Cmdr. Stephen Clawson. " . . . We are convinced that the urine sample identified as Midshipman Bellistri's does, in fact, belong to him."

The Bellistri cocaine case has caused little debate among midshipmen at the Naval Academy, according to Scott Ordich, his roommate. He said most students assume the drug tests are accurate and Bellistri is guilty. But after three years of friendship, Ordich said, he could tell that Bellistri wasn't lying when he said he didn't take cocaine. Ordich said he believes the drug tests are, on the whole, accurate and necessary -- but that a mistake was made in Bellistri's case.

The Navy is proud of its drug-testing program, which began after marijuana was found in the bodies of six U.S.S. Nimitz sailors killed in a 1981 plane crash on the carrier's deck. About 1.8 million urine tests are conducted in the Navy each year. Since 1981, 18,710 Navy members have been dismissed for drug use.

Navy spokesman Lt. Stephen Pietropaoli says the drug testing program is working. In 1980, he said, 48 percent of junior enlisted men tested in Norfolk and San Diego had evidence of marijauna and hashish. By 1984, that figure had dropped to 10.4 percent.

After some "glitches" in 1982 -- in which thousands of military personnel were dismissed from service and then offered their jobs back -- Pietropaoli said Navy drug tests improved and are now rated as excellent. He said there has not been one false positive in more than 20,000 tests.

Pathologist Dr. William Manders, a retired Air Force colonel who helped set up the sweeping urinalysis program, said said that despite improvements, many possibilities for error remain and that it is unfair to dismiss a serviceman on the basis of a single urine sample.

Among other problems, Manders said that packing tape used to seal sample boxes is "not foolproof" and that laboratories have been known accidentally to switch samples. "This becomes very disturbing because someone's career is riding on one urine test," he said.

Manders said many problems could be overcome by obtaining two samples from each person.

Navy spokesman Pietropaoli disagreed. "Why not four samples?" he said. "Why not six? Where's the cut-off? We feel that the very exact system we have now produces exact results. We admit that any system has a potential for a mistake." But when there is doubt, "we resolve those cases in favor of the individual."

Naval Academy officials maintained the level of cocaine traces found in Bellistri's urine sample -- 4,849 nanograms per liter, or around 16 times the military's "positive" level of 300 nanograms -- was so high it "negated" the possibility of accidental ingestion. But Manders and others familiar with the urinalysis program disagreed.

Mark Waple, whose law firm near Fort Bragg, N.C., handles around four military urinalysis cases a week, said one Army client unwittingly consumed a Christmas punch spiked with cocaine, and that cocaine traces were subsequently measured at around 4,000 nanograms per liter.

Waple said one of the major problems with current military urine testing is that careless or harried laboratory workers don't keep a close eye on samples, get them mixed up or allow them to become contaminated.

But one expert frequently called to testify at military hearings on scientific aspects of urine testing, North Carolina Medical Examiner Arthur McBay, said he regularly reviews data from military urinalysis labs and has a high opinion of the Norfolk lab where Bellistri's sample was handled.

Bellistri says he has little doubt that some students at the Academy experiment with drugs. He said experts on drug use who testified at one of his hearings estimated that somewhere between one percent and 25 percent of students there do. A second midshipman accused of using cocaine, after a later urinalysis sweep at the academy, is in the midst of hearings.

Bellistri said he will continue fighting the accusation. "You want to clear your name," he said. "It's easy when you are not guilty."

"I have something to give to the country," Bellistri said. "Not many people nowadays even volunteer for enlistment and here I am wanting to, and they are stopping me . . . . "

If he were guilty, he said, he would not pursue the fight. "I'd go to another school and get a degree."