Twelve employes of a subcontractor who maintains the automatic fare-collecting equipment for Metro were fired last week after a marked increase in equipment failure and Metro complaints to the equipment manufacturer, officials said yesterday.

Herbert Long, president of the minority subcontractor, Unified International Inc. (UII), charged yesterday that the problems were in the farecard equipment, not in its maintenance. The equipment is manufactured under a $53 million contract by Cubic Western Data, a San Diego subsidiary of the Cubic Corp.

Cubc Western is also responsible for maintaining the farecard equipment under a one-year, $953,000 contract with Metro. Much of that maintenance work was subcontracted by Cubic to UII.

Long also charged that Cubic had employed UII only to meet Metro's minority hiring requirements and that it had "no intention of honoring its commitment to the minority firm." Cubic denied that charge.

The issue is the performance of the farecard equipment, which vends magnetically encoded subway tickets, read them at both entrance and exit gates to the stations, and collects fares from the tickets before returning them to the rider.

"I have been leaning on Cubic," said Nicholas A. Roll. Metro's assistant general manager for transit services. "I am dissatisfied with the performance of the equipment. I'm not sure whether its equipment or people."

Roll said the farecard had gotten noticeably worse since Aug. 1. For example, on July 2, only 26 of the 256 farecard vending machines showed red "out of order" lights at the start of business. But yesterday, 44 vendors - 17 percent - were out of order.

Thomas N. Tuttle, project manager for Cubic Western, said, "We have seen in the past when we can keep the morning report at an acceptable level - maybe 2 to 5 percent out. We get pretty emotional" if it's higher than that, he said.

He confirmed that Cubic Western had directed the dismissal of the 12 employes, leaving UII with six. "We feel Cubic has a responsibility to Metro and the public and we also recognize fully our minority development commitments," Tuttle said. He said that, by conservative estimate, $5.9 million in Cubic subcontracts for Metro projects was assigned to minority firms.

Since mid-June, Tuttle said, Cubic has been replacing UII supervisory and maintenance personnel with its own and with some temporary help hired elsewhere.

Thomas Saavedra, one of the fired employes who called The Washington Post, said "They did not give us a reason, but just picked up our keys (to the machines), and the fare manual."

Cubic concedes that it has one major equipment problem common to all the farecard machines. That problem rests in the system of belts and pulleys that pulls farecards through the machines and returns them to riders.

A new system has been developed and tested and will be installed in all the equipment here when parts are available. "We are having trouble getting castings right now," Tuttle said, "and I cannot promise a date."

UII sent copies of its side of the story and pertinent correspondence to a number of local officials yesterday. In a cover letter, UII board chairman Theodore A. Adams Jr. said the board had agreed yesterday "to relinguish control over the personnel to Cubic for purposes of technical supervision."

Adams asked for meetings with various Metro officials and for legislation that would "prevent majority firms from using minority firms to obtain contracts under affirmative actions programs without sufficient enforceable contractual authority . . . to prevent the elimination of the minority subcontractor immediately thereafter, without just cause."