Inside the New York Bulk and Foreign Mail Center here, two armed guards keep a 24-hour-a-day vigil at outbound loading dock 254.

On Dec. 15, while working alone at dock 254, a 25-year-old mail handler, Michael McDermott, was pulled inside its conveyor belt and crushed to death. The belt lacked the protective shinguard that could have saved his life, and there was no emergency stop switch within his reach. Both deficiencies had been brought to management's attention months earlier.

When McDermott was found, there were no medical personnel in the facility, which employs 4,100 people. Dock 254 has been shut down while an investigation is conducted.

Less than two weeks after McDermott's death, postal distribution clerk Frnk McGhee's work apron caught on a similar conveyor belt, dragging him into the loading machine before a coworker could pull him free. McGhee, now recovering from what his physician describes as "severe contusions and a badly sprained neck," says: "I'm upset about the place and so are all the workers there. It doesn't make any sense that the post office wouldn't look for safety hazards."

The two accidents have focused attention on safety standards at such plants throughout the postal service, in particular the Jersey City facility, the largest of its kind in the world.At the request of plant management, the federal Occupational Safety and Health Administration is investigating the two accidents as well as other safety conditions.

The facility, after the Colgate-Palmolive factory the largest single employer in Jersey City, processes between 350,000 and 400,000 parcels a day, and up to 500,000 a day during the Christmas season.

Postmaster General William Bolger and Alexander Gallione, the Jersey City plants's manager, have refused to answer any questions about the death of McDermott, who had worked at the plant more than four years.

"I'm not aware of unsafe conditions. I'm not going to discuss the accidents," Bolger said at a New York City news conference last week.

A safety report prepared by plant management on March 7, 1979 -- nine months before McDermott's death -- and made known to the head of plant maintenance, Chester Bojan, was obtained by The Washington Post. It takes note of the defective belt on which the mail handler was killed: "No safety plate on head end, no switch on head end, wires hanging under belt, no guard right side." Nothing was done to repair the belt.

The day after McDermott's death, coworker Ron Papa prepared a 12-page report, with management's approval, on safety conditions at all of the outbound loading docks. Each of the loading areas and the conveyor belts they house, Papa wrote, was found to have at least than three major safety defects. ysome of the devices were in violation of as many as eight safety requirements.

"Everybody's afraid of the belts," Papa concluded. "You can complain for months about a safety problem and nothing is done."

Because of a "split lunch" policy that leaves machinery workers alone to keep up production, John D'Agostino, McDermott's partner at dock 254, was in the plant cafeteria at the time of the accident. He recalls, "I talked to him before lunch. He was a pleasant guy. I came back and he was dead." D'Agostino explains that the jam relay switch, which ordinarily would have stopped the machine if something became caught in it, had been intentionally disconnected.

Bob Kirkland, a mechanic at the facility for five years, says, "It was common practice to disconnect these switches because they slowed production."

The Jersey City accidents have fueled union charges that postal workers are forced to work in unsafe conditions. "Safety rules are cut in order to save money," says Emmett Andrews, general president of the American Postal Workers Union (AFL-CIO). "Management is cutting the maintenance force. McDermott was alone in there . . . It's criminal!"

Union officials have accused plant management of disregarding regulations in the U.S. Mail Safety Rule Book, one of which states that "no employe is permitted to operate defective machinery or equipment." At the New Jersey facility, the union has charged that some workers have been fired because of their repeated demands for safer working conditions; some have regained their jobs after arbitration hearings.

Jersey City plant worker Clyde Dinkins claims "there were 1,765 accidents in the plant in 1978, 700 of which were disabling. In any part of that building there are thousands of [safety] violations."

Dinkins says he was demoted from supervisor to clerk last August after he ordered men on his 60 loading docks to stop working because the areas were unsafe.

In January 1979, Dinkins wrote President Carter, warning of "hazardous, unsafe conditions." A Carter staff aide, Landon Kite, replied June 20 that "a number of your charges have been substantiated and Postmaster General Bolger's office is initiating action."

Dinkins wrote again last September pointing out deficiencies on conveyor belts. "Must someone lose a limb or be killed before you take action?" he wrote. There was no written reply.

At the urging of Rep. William Clay (D-Mo.), and William G. Guarini (D-N.J.), the House Post Office subcommittee on postal personnel and modernization, along with the House subcommittee on health and safety, will hold public hearings at the plant today and tomorrow. Lloyd Johnson, a psokesman for Clay, says, "the Postal Service places employe safety second to the moving of mail. Management tends to blame workers and not faulty engineering."

A preliminary OSHA report released to management and union officials Saturday dealt only with the conveyor belt in which McDermott died. Investigators found 12 "serious" mechanical defects in the belt. The Postal Service, a federal agency, is not required by law to obey any OSHA recommendations. A House-passed bill to mandate adherence to OSHA recommendations is now before the Senate.