Just about a year has passed since the glorious moment last Feb. 16 when senior Communist Party officials of the Leningrad region dedicated the long-awaited, badly needed Siversk tractor repair factory.

Crucial to raising productivity of the collective and state farms of the area, the facility was to overhaul 14,000 large farm tractors a year.

"It is not a factory, it is a beautiful piece of art," the party newspaper Pravda recently reported. "It is the largest enterprise of an industrial branch that fully meets the needs of collective and state farms in the northwest regions of the non-black earth zone."

Pravda reserved special praise for the senior officials who approved the plant, and reported its progress to completion. This made a long list of important veteran administrators.

"There are many, many others who helped achieve this triumph over difficulty," noted the paper.

There is only one problem with the factory, Pravda then noted: it doesn't exist.

Although it is on the official books as one of the region's most important achievements, the "factory" in fact is a collection of roofless buildings in a rubble-strewn industrial site hidden from the curious behind a solid fence, presided over by an elderly watchman.He carried a rifle but his chief enemy seems to be solitude.

This latest example of major fraud may be no real surprise from a country with a well-documented history of deception dating back at least to the famous fake villages built by Potemkin to fool Catherine the Great.

But the case illuminates the bizarre problems facing the U.S.S.R's powerful central planners as they grapple with steadily falling economic growth rates.

The gap between plan goals and production has not been greater in recent Soviet history than in 1979, the year of lowest economic expansion since post-World War II reconstruction years. Aside from difficulties in basic industries and snarled transport, a major factor in slowed growth is the continuing inability of construction trusts to complete projects. About 80 percent of projected factories, institutes and housing projects are reported to be unfinished. Soviet President Leonid Brezhnez has repeatedly warned against such shoddy performance.

Officials of the Leningrad Oblast Construction Trust No. 49 faced lags almost from the moment their new factory project got under way in 1974.

Pravda, in recounting the saga of the phantom factory, reported how the officials simply papered over the lags by signing off on the myriad legal documents that accompnay any Soviet project. The administrators reported step by step that their factory was near completion and ready for installation of the machines to recondition tractor engines.

Now the equipment trust was in trouble. How could it refuse to install machines if the factory was ready for them? To do otherwise would be to risk criticism from above and damage carefully nurtured careers. Like any good shaggy dog, this one simply grew more hair.

The suppliers passed along their signed documents and now the facility was ready for production.Meanwhile, the situation has become complicated by the fact that an older repair factory -- a real one-- had been torn down to clear the way for more efficient production from the new one.

Deception folded within deception. The local environmental man signed a document saying the factory was non-polluting and okay with him. He argued lated to investigators that he was perfectly correct in issuing this document since he knew the plant did not really exist and therefore could not pollute.

The deception was so complete -- for a time -- that the chairman of the State Committee of Agricultural Technical Means of the Russian Federation, N. V. Bosenko, recommended that others get medals and state orders of congratulations.

But the investigators finally closed in and uncovered the factory as a phantom of official bookkeeping. A number of officials were punished by demotion but the problem still remains for the Leningrad Oblast farmers -- no tractor repair facilities. This one, summed up Pravda, "worked on paper fuel. Let's see how soon they will launch a factory that actually repairs agricultural machines."