First-quarter profits at Fairchild Industries fell by nearly half, from 94 cents a share to 50 cents a share, stockholders were told yesterday.

Earnings for the first three months of 1982 were $9.3 million, compared with $17.4 million for the comparable period of 1981. First-quarter revenues declined to $262.5 million from $312.2 million a year ago.

Edward G. Uhl, chairman, president and chief executive of the Germantown, Md., company, told stockholders that the results were slightly ahead of 1982 projections, which anticipated downturns because of the recession.

Fairchild is an aerospace, commercial-industrial products and communications company.

Washington Gas Light Co., which reports earnings on a 12-month basis every month, said colder weather, higher rates and more customers raised its profits for the latest period.

For the year ended March 31, WGL had net income of $21.4 million ($3.64) compared with $17.5 million ($3.38) a year ago. Therm sales increased to 1.16 billion from 1.12 billion over the same period.

Ryland Group Inc. first-quarter profits nose-dived 91 percent to one cent a share, the company said.

Profits for the Columbia-based home builder were $41,000 for the first three months of 1982, compared with $453,000 (15 cents) last year.

Ryland's sales were $39.2 million this year, compared with $52.7 million for the first quarter of 1981.

Pargas Inc. of Waldorf, a distributor of liquefied petroleum and equipment, reported yesterday that earnings and revenues for the first quarter of 1982 slipped because of losses from coal operations.

Earnings were $4.4 million ($1.05) compared with $5.5 million ($1.33) in 1981. Revenues were $78.5 million compared with $83.4 million.

Pargas' principal coal customer had a breakdown in loading equipment, forcing a suspension in shipments and resulting in the loss to Pargas.

Shipments have resumed, Pargas said, but will not return to previous levels the rest of this year.

Baltimore-based USF&G Corp., a multiline insurer, yesterday posted a first-quarter operating profit of $35 million ($1.23) compared with $46 million ($1.46) for the comparable period of 1981.

First-quarter earnings jumped 59 percent at Farmers and Mechanics National Bank of Frederick, No. 9 in Maryland.

Profits were $795,700 ($1.27 a share) compared with $500,300 (80 cents) a year ago. A one-time interest recovery contributed 21 cents a share to the first-quarter figures, bank officials said.

Deposits grew to $233 million; loans increased to $152 million and assets increased to $267 million during the first quarter of 1982.

President Charles W. Hoff III said, "IRA deposits are flowing into the bank as a result of good promotion," and he expects to have automated teller machines available to all customers by year-end.

Avemco Corp. of Bethesda, a national aviation insurance, financial services and product marketing organization, posted record earnings for the first quarter of 1982 of $1.3 million (54 cents a share), an 18 percent gain from last year's $1.1 million (46 cents).

Revenues in the first quarter also were the highest ever, growing 23 percent from last year, to $8.6 million from $7 million.

Chairman Arnold Johnson attributed "a significant portion" of the 1982 performance to investment income, which went up 19 percent.

Avemco Insurance wrote record premiums, also adding to the favorable figures.