As one of the steps in making parts for the Boeing 757 and Air Force A10 combat-support plane, workers at Fairchild Industries Inc.'s huge plant here rinse the parts in giant tanks containing a chemical solution.

That solution is then drained from the tanks and either recycled or moved to plants elsewhere in the complex or in Baltimore to be disposed of safely.

At least, that's what's supposed to happen. But the hazardous waste strike force of the Maryland attorney general's office charges that between October 1980 and December 1981 more than 200,000 gallons of waste solution was improperly dumped or leaked out and seeped into water supplies and ground around the plant. The alleged violations have since been corrected, state officials say.

The solution contained hexavalent chromium, chromic acid and nitric acid--all identified by state officials as "corrosives" that could cause irritation or burns in large doses. So far, however, no health problems have been reported and drinking water remains safe, tests by the state health department show.

State officials brought an 86-count criminal indictment last September charging the company with allowing the alleged leakage of the toxic solution. Jury trial of the case is to begin today before Washington County Circuit Court Judge Frederick C. Wright III and is expected to last about four weeks. If convicted on all counts, Fairchild could face more than $2 million in fines, the highest ever in a Maryland antipollution case.

Fairchild has denied the allegations and promised to contest them vigorously. But it has so far failed in attempts to block the case on technicalities from coming to trial. One failed attempt was to challenge the jurisdiction of the hazardous waste strike force, which was formed in 1981 and has successfully prosecuted several criminal cases.

The Hagerstown case has also spawned litigation by four former Fairchild employes, who charged in suits filed late last month that the company defamed them by suspending them a year ago during the grand jury investigation into the matter. The employes, all former foremen at the Fairchild plant here, are seeking more than $83 million in damages from the company.

Local reaction to the Fairchild case has been muted, Hagerstown officials say. The plant is the largest employer--about 2,000 workers--in a town hard-hit by the recession, and there is apparently an unwillingness to antagonize Fairchild by speaking out. But the trial is being closely watched here.

The number of counts in the indictment against Fairchild is so high because there is a count for each time the company is alleged to have let the chemicals seep out of the plant. But the state's case is based essentially on repeated incidences of two violations--the alleged discharge of waste chemical solution from one tank "flowing into an open drain from which it flowed to ground water"; and a leak in a concrete pit used to collect the solution, which allowed it to seep out.

The state has charged that Fairchild knew about the problems but did not correct them until state health officials detected the chemicals and complained.

The suits filed by the former employes make similar charges. One says that the four foremen "had repeatedly requested that Fairchild make certain additions or repairs which were essential in order to allow the wastewater treatment facilities to properly handle the quantity of hazardous waste generated." The suit alleges that these requests were continually denied.