DYESS AIR FORCE BASE, TEX. -- In a softly lit room in the B1 bomber training school here, young Air Force officers hunch over a panel of radar screens and electronic gadgetry, learning to manipulate the defenses designed to protect plane and crew during bombing missions into the heart of the Soviet Union.

But it could be years before the officers use the sophisticated avionic equipment outside the simulated cockpit of the schoolroom. In real life the equipment does not work, and the problems are so serious the Air Force does not know when they will be fixed.

Six years after President Reagan declared the B1 bomber the centerpiece of his plan for improving the nation's strategic forces, the dismal failure of the plane's electronic brains has crippled its ability to carry out its most important missions, according to government officials and congressional leaders.

Dozens of other technical problems, from faulty flight controls to malfunctioning computerized maintenance systems, have delayed crew training and sharply restricted the number of bombers the Strategic Air Command can place on alert, according to the General Accounting Office (GAO), Congress' fiscal watchdog. Air Force officials say it will be 1990 before 30 percent of the new planes can be kept on alert, the standard percentage for quick response. Now, only one plane is on alert of 54 bombers in the force.

The costly additions to the U.S. triad of strategic forces -- B1 bomber, ground-based MX missile and huge Trident missile-carrying submarine -- are critical to protecting the nation and deterring war, the administration says. But the B1's deficiencies, coupled with recent disclosures of MX missile guidance problems and defects in air-launched cruise missiles, or ALCMs, raise serious questions about how well-protected the nation is as the Reagan era nears a close.

"The Reagan Pentagon is not doing well with its strategic initiative . . . . The triad is not as strong as it's supposed to be," charged Rep. Les Aspin (D-Wis.), chairman of the House Armed Services Committee and an outspoken critic of the president's strategic forces. "We're not getting our money's worth."

The $28.3 billion bomber program is an expensive example of a weapons system gone awry in the rush to keep political promises. Its history shows how Congress, the Pentagon and the defense industry became so consumed with trying to achieve politically driven production deadlines and spending limits that they ignored -- and frequently covered up -- serious technical problems critical to the bomber's ability to do its job.

The Air Force, eager for its greatest showpiece in the $2 trillion Reagan defense buildup, used high-risk shortcuts in building and overseeing one of its most costly and complex weapons systems.

Some top congressional leaders, Air Force officials and military specialists say those efforts to save money and reduce production times have left the Pentagon with an expensive bomber unable to perform some of its most important jobs: missions that would bridge the gap between the aging B52 bombers and the new "Stealth" Advanced Technology Bomber, scheduled to become operational in the early 1990s.

Other Air Force officials counter that despite its problems, the B1 met a rigorous production schedule and can carry out many of its intended missions. They also note that problems are not uncommon in new weapons systems and that the Air Force has cured many of the plane's early technical difficulties.

"The B1B is the best warplane in the world today on anybody's side," Gen. John T. Chain Jr., commander of the Strategic Air Command, told a House committee in March.

"It might be the best plane ever made -- except it can't do its mission," said Frank L. Conahan, director of the GAO's National Security and International Affairs Division, which has conducted numerous investigations of the B1's problems.

The bomber's ultimate mission is to dart through the Soviet Union, flying low and fast enough to avoid radar detection, and destroy the most sensitive and strategic Soviet targets. It is built to be so automated that it dodges mountains and enemy attacks before the pilot in the tiny cockpit realizes he is in danger.

Because of the plane's technical problems, none of its crews have been trained to use its full, planned capability, according to the GAO. Its report said Air Force officials told investigators that, in a national emergency, "all B1s would be available within days."

For emergencies that could require only a few minutes or hours of reaction time, Air Force officials said, many of the older B52s now on alert would be available. Because of the large staffing and mechanical resources required to keep B1s on alert, officials said, putting more of them on alert now would hamper efforts to improve crew training and correct the bomber's technical deficiencies.

The problems with the B1s, which cost $280 million each, have prompted Congress to scrutinize more closely other weapons programs managed under similar conditions.

Committees have demanded new details on the secret Stealth bomber program, while the GAO has reported that the Navy's new Seawolf submarine could encounter some of the same development and procurement problems as the B1, noting that there is a "high risk" the vessel may not be able to perform its full tactical capabilities when delivered to the fleet.Resurrected by President Reagan

In a Pentagon arsenal filled with political weapons, the B1 is perhaps the most political. It was conceived in one Republican administration, killed by a Democratic White House after four planes had been built, then resurrected by Reagan as a cornerstone of his efforts to strengthen national defense.

Congress approved resumption of the program under the strict condition that the 100-bomber fleet could cost no more than $20.5 billion in 1982 dollars, or $28.3 billion in today's dollars. It mandated that the first bomber be operational by 1986 and all be operational at four midwestern airfields by April 1988.

The Air Force, hungry for a new bomber program, insisted it could meet the tough demands. It worked diligently to prove it could remain within its budget, cutting corners and whittling back parts of the B1 program. It persuaded Congress to accept special cost-cutting contracting arrangements even though the B1 program did not qualify under the military's requirements.

But far from controlling costs, the spending cap "provided a mythical ceiling and diverted management initiatives into efforts to locate ways around the cap," according to a 1982 GAO investigation. "Billions of dollars devoted to the B1 were tucked into other programs to avoid the cap."

The GAO found that the Air Force had disguised extra costs for such key items as training simulators, engine parts and maintenance depots.

Other features were removed from the original budget as "unneccessary" only to resurface in new budget requests as "enhancements" needed to meet a changing Soviet threat.

Richard D. DeLauer, then-Defense Department director of research and development, told the House Appropriations subcommittee on defense in 1982, "If some of these changes are too expensive, we will not do them. The FLIR {Forward Looking Infrared sensor}, for instance, is not worth much in a modern penetrating bomber. We are not going to put it in."

The late Rep. Joseph P. Addabbo (D-N.Y.) shot back: "I will mark those words down in red and wait a year from now when you come back and ask for that money."

Five years later, the Air Force came back. Its 1988 budget asked Congress for a $665 million program to equip the bombers with FLIR as a crucial aid to crews during low-level flights and to enable night landings on blacked-out airfields.

Early in the program, the Air Force cut its flight testing program to remain within the budget, only to return to Congress this year asking for hundreds of millions of dollars to add flight tests.

In the race to slash expenses, the Air Force and its contractors took other costly shortcuts. They used the old aerodynamic engineering data from the four bombers built before President Jimmy Carter killed the program. But engineers added 41 tons in new structures, weapons capacity and fuel loads to the new B1, causing major flight control problems in a plane that now weighed 238 tons. Air Force officials said they were forced into expensive revisions of the data to conform to the new model.

To save money, the Air Force outfitted the B1 with the same pilot seats used in the F16 fighter, which is designed for far shorter missions. In the B1, with sorties that can last longer than six hours, the seats caused lower-back muscle spasms in pilots after barely two hours of flight, according to pilots and Air Force documents. The seats were later modified at additional cost.A High-Risk Procurement Plan

Of all the cost-cutting, time-saving efforts, the most controversial was the Air Force decision to use a high-risk procurement plan, called "concurrency" in contracting jargon. It meant that the Air Force developed the B1's parts at the same time the plane was on the assembly line.

Air Force officials say this was the only way they could produce the plane quickly enough to meet Congress' stringent guidelines, even though it left virtually no margin for error to accommodate problems.

"Concurrency, if properly planned, is an excellent way to save money and speed up the process," said Richard P. Godwin, the Defense Department's current acquisitions chief. But, he said, "I think the B1 is not necessarily a good case for concurrency."

The system allowed Rockwell International Corp. to gear up its assembly line quickly. Within three years of signing the contract to build the airframe, Rockwell rolled out the first plane on a runway in the California desert east of Los Angeles in September 1984.

Because of the hectic production schedule, there was little time -- in some cases, no time -- to test the bomber's subsystems. As a result, many components did not work once they were assembled.

Rather than slow the main production line, Rockwell delivered some bombers with flawed parts, while others lacked some of their most critical components, including the sophisticated electronic countermeasures {ECM} system produced by Eaton Corp.'s AIL Division.

The irony was that Reagan had used that system's advanced capabilities as a key B1 selling point. Its sophisticated computers and electronic eyes, contained in 108 black boxes, are designed to spot possible attacks and jam Soviet defenses, rendering them impotent against the swift bomber.

Individually, many of the boxes worked. But when the 2 1/2-ton system was assembled, the software in many of the boxes was incompatible with other boxes. In one of the worst cases, the plane's electronic jamming devices not only were unable to jam Soviet defenses, but they served as a beacon that would draw Soviet radars directly to the plane.

"It would be like turning on a flashlight in a dark room," said Capt. Fred Strain, one of the officers trained to operate the B1's defensive avionic equipment.Acting as Own Prime Contractor

Some Air Force and other government officials say the military may have been slow to recognize and react to those problems because of another controversial decision -- allowing the Air Force to act as its own prime B1 contractor instead of paying a defense contractor to oversee the 5,000 subcontractors it had hired in 48 states.

The Air Force said the decision saved taxpayers millions of dollars. But it also meant the Air Force was serving as its own watchdog over the contractors and the assembly of the airplane.

"The capability of a military organization, the Air Force, to serve as prime contractor and integrator for the program was not adequately challenged," said John E. Krings, Defense Department director of testing and evaluation. "To my knowledge, no one questioned the ability of a service to carry out such a function. It was simply assumed."

Because bombers were being delivered on time and under ceiling cost, there were few suspicions outside the Air Force that major shortcomings lurked beneath the shadowy gray-green skin of the sleek aircraft. Regular status reports to Congress proudly declared the plane was being built on time, making virtually no mention of the problems.

Last year the B1 program office even won the Secretary of Defense Management Award for "exceptional performance."

Defense Secretary Caspar W. Weinberger, describing his twice-a-month meetings with B1 program managers, told the House Armed Services Committee, "There are only two or three basic questions asked and that is all: Are you on time? Are you within your budget? And, if not, why not?"

Countered the GAO's Conahan, "The question to ask is 'Can it do a low penetrating mission into the middle of the Soviet Union and do that undetected by Soviet radar?' The answer is . . . it can't do its mission."

Air Force officials, convinced they could correct most of the problems, did not volunteer details of the problems even when reporting to Weinberger, according to Krings. "No, I don't think that they were completely candid, no," Krings told the House Armed Services Committee in March.First Inklings of Major Problems

The first inklings of major B1 problems were revealed last summer during a closed-door briefing on the Stealth bomber presented to the House Armed Services Committee by the GAO. According to Conahan, GAO officials mentioned the B1's problems during questioning about the Stealth.

But when the first B1s officially entered the Air Force fleet last September, military officials and defense contractors declared it a production miracle. Four years after the production contract was signed, a squadron of the powerful war machines lined a runway on the Texas plains, ready to go on alert and perform their mission.

What the Air Force did not say about the bomber was that it could perform only part of its intended mission. The plane was not ready to be flown at its most effective terrain-hugging levels. Its electronic jamming equipment did not work. There were flight-control failures, a bomb bay door malfunction that sent bombs spiraling out of control and a computerized maintenance system that gave off so many false alarms that the crews considered it unreliable for detecting real problems.

The revelations, which did not become public for several weeks after the bomber was declared operational, stunned members of Congress who had not yet received a full briefing on the GAO findings. Even Weinberger reportedly was furious that top Air Force leaders had not adequately warned him about the problems, according to Pentagon officials.

Both the Air Force and contractors have scrambled to correct many of the problems. Rockwell International dispatched dozens of employes to Dyess AFB, near Abilene, Tex., in a round-the-clock effort to stop fuel leaks plaguing many of the planes. Dozens more engineers and specialists have been sent to Eaton's Long Island plant to try to solve the ECM problems. The Air Force has withheld more than $300 million in contractors' payments in an effort to spur their cooperation in solving those and other problems.

While Air Force officials and contractors say they have either fixed or found a way to correct many of the B1's problems, they concede that the ECM system, which is the greatest problem, may not be fully operational until 1991. Further, they say the problem is compounded by continuous changes in the Soviet threat, which force engineers to try simultaneously to correct problems in software designed to meet current threats as well as improving software to combat future threats.

Aspin said the bomber is capable of performing about 60 percent of its intended mission and will be about 80 percent effective after the Air Force implements the planned improvements.

Air Force officials boasted that the B1 celebrated the Fourth of July by breaking four world records and setting 14 new standards for a combination of speed, distance and payload. The bomber lugged 33 tons of water simulating a payload of missiles for the exercise.

Still, the plane continues to be plagued with embarrassing difficulties. In June, the Air Force took the bomber to the Paris Air Show, one of the most prestigious international stages for aeronautical equipment.

Thousands gawked, but after the show, when the crew prepared to fly it home, the B1's engines refused to start because of a failure in the auxiliary power unit. The plane left Paris a day late, after the Air Force trucked in a 230-volt ground power unit to jump-start the engines.