During the past three months, more people were traveling on USAir. More people were buying Black and Decker power tools. And more Pepco customers were waste-watching. But only Pepco made more money this quarter than it did in 1982.

Potomac Electric Power Co. officials said yesterday that first-quarter profits increased to $22.7 million (40 cents a share) from $19.9 million (36 cents) in 1982. Revenues over the period slipped from $254 million in 1982 to $253.8 million in the three months ended March 31.

For 12 months ended in March, Pepco earned $121.7 million ($2.32), compared with $111 million ($2.15) the year before.

USAir Group Inc. posted a loss of $1.9 million for the first quarter, traditionally the airline industry's worst period. Last year, USAir earned $10.8 million (62 cents) in the first quarter, but that included a $27 million gain when it sold the tax benefits on seven aircraft.

Comparing operating results quarter to quarter, USAir lost $408,000 this year and $4.9 million last year. Chairman Edwin I. Colodny said the airline had increased its traffic and passenger load factor and cut its cost per seat, which helped offset the heavy fare discounting during the quarter.

Total operating revenues at USAir amounted to $311.7 million, compared with $279.2 million in 1982.

At Black and Decker Manufacturing Co., suffering as consumers spent less for power tools in the recession, second-quarter volume has increased year-to-year for the first time since June 1981.

Sales, however, slipped 3 percent to $301.6 million from $310.8 million. Net income was $13.2 million (31 cents), compared with $12.6 million (30 cents) in 1982. Last year's results, however, include provisions for estimated losses on the sale of the McCulloch chain-saw division. Comparing earnings from continuing operations, B&D had $18.2 million last year, which dropped 28 percent to $13.2 million this year.

For the six months ended March 27, Black and Decker had earnings of $27.6 million (65 cents), compared with $27.7 million (66 cents) the year before. Sales dropped to $600.5 million from $637 million.

Continuing its management shake-ups, Black and Decker President Laurence J. Farley yesterday named Robert L. Swam to be chief operating officer, with responsibility for worldwide operations. The changes reflect the Towson company's continuing concern over its worldwide operations, with Swam previously in charge of North America, Latin America and Asia.

Other changes in the organization, which eliminated "a layer of management," include seven group vice presidents: Kenneth R. Wells, North American consumer power tools; James F. Barcus, North American professional power tools; Stephen J. Britt, North American household products; Arnold L. Breidenbaugh, Southern Hemisphere; Roger H. Thomas, British Isles; Guenter Cott, Northern Europe; Roger F. Leverton, Southern Europe.

Three senior vice presidents are Nigel P. Hamilton, manufacturing and technical development; Robert H. Alcock, chief financial officer, and John I. Leahy, market and product development.

Another Maryland firm in the hand-tool market, Easco Corp. of Baltimore, said yesterday that first-quarter profits were $2.5 million (65 cents), compared with $2.7 million (71 cents) last year. Sales increased to $111.8 million from $101.3 million.

Company officials noted that sales and profits have increased from the fourth quarter of 1982, however.

Syscon Corp. reported record results for the first quarter, earning $689,000 (26 cents), compared with $440,000 (16 cents) in 1982. Revenues increased 15 percent to $18.8 million from $16.4 million.

Syscon, based in the District, develops, sells and manages computer software and microprocessor products.

Equitable Bancorporation's profits jumped to $3.1 million (65 cents) in the first quarter from $1.9 million (48 cents) in 1982, company officials said yesterday.

Assets of the Baltimore-based bank holding company increased 22 percent to $2.5 billion from $2.1 billion.