Dynalectron Corp. has reported its earnings declined in the second quarter and first half of 1982, but said the profits were still the second-best in its history.

Among other area companies reporting financial results, Financial General Bankshares said its profits slipped in the latest quarter but were unchanged for the first half of the year, while American Management Systems Inc., which reported losses a year ago, showed profits for the first two quarters of 1982.

Dynalectron, a diversified electrical engineering, contracting, aviation services and energy research company based in McLean, reported earnings of $3.3 million (38 cents a share) in the second quarter of 1982, down from last year's record earnings of $4.4 million (51 cents). Revenues in the 1982 period totaled $111.3 million, down from $122.7 million in the 1981 period.

Earnings for the first half of 1982 totaled $5 million (58 cents) on revenues of $218.5 million, compared with last year's first-half record earnings of $5.4 million (63 cents) on revenues of $230.5 million.

The company noted that its first-half earnings approximated the full-year earnings of 1980, the 35-year-old company's second most profitable year.

Dynalectron reported continued growth in its government services activities, increased earnings from its commercial aviation activities and the operations of a new air cargo subsidiary acquired in March, and net interest income from liquid capital investments.

Partially offsetting these factors, the firm said, were the continuing adverse trends worldwide in the petroleum and petrochemical industies, craft union strikes in some parts of the United States and Canada, and the credit failures of several customers which resulted in write-downs of receivables.

Financial General Bankshares reported second-quarter 1982 net earnings of $5 million (69 cents), compared with $5.2 million (71 cents) in the 1981 period.

A holding company for banks in Washington, Virginia, Maryland, New York and Tennessee, Financial General said net earnings for the first half of 1982 totaled $10.1 million ($1.38), the same as in the first half of 1981.

American Management Systems Inc. reported earnings of $186,000 (11 cents) for the second quarter of 1982, compared with a loss of $229,000 in the comparable 1981 period. Revenues for the two periods were unchanged at $16.5 million.

Arlington-based AMS, a nationwide computer systems and services firm which also has a specialized management consulting practice, reported first-half net income of $343,000 (21 cents), compared with a loss of $90,000 in the first half of 1981. Revenues in the latest six months totaled $33.8 million, up 8 percent from $31.4 million in 1981.

The company attributed the results to improved performance in its packaged systems and computer services segments, which more than offset increased interest expense and declines in its custom systems and federal consulting segments.

Baltimore Gas & Electric Co. reported that net income in the second quarter of 1982 totaled $38 million (86 cents) on revenues of $366.1 million, compared with $31.4 million (74 cents) on revenues of $314.2 million in the 1981 quarter.

In the first half of 1982, the Baltimore utility earned $83.9 million ($1.99) on revenues of $829.3 million, compared with earnings of $74.9 million ($1.89) on revenues of $698.6 million in the 1981 period.

Easco Corp. of Baltimore reported net income of $3.3 million (87 cents) in the second quarter, a 16 percent increase over $2.8 million (85 cents) in the comparable period a year ago. Net sales were $106 million in both periods. Six-month 1982 earnings totaled $5.9 million ($1.58), an 11 percent increase over earnings of $5.3 million ($1.60) in the first half of 1981.

While sales in Easco's business lines--hand tools, aluminum extrusions and industrial products--continue to be adversely affected by the weak national economy, its president, Richard P. Sullivan, said that earnings are being favorably influenced by increased productivity and efficiencies in mechanics' hand-tool manufacturing, lower raw material costs in aluminum and by an overall cost reduction program, including lower pension costs.

Citizens Bank and Trust of Maryland reported net earnings of $4.5 million ($2.51) for the second quarter of 1982, compared with $3.9 million ($2.17) in the year-earlier quarter.

For the first half of the year, Citizens posted net earnings of $8 million ($4.46), compared with $6.5 million ($3.60) a year ago.

The Ryland Group reported net earnings of $605,000 (20 cents) for the second quarter of 1982, down 39 percent from $984,000 (32 cents) a year ago. For the first six months of the year, Ryland, a Columbia, Md.-based builder of single-family houses, reported net earnings of $646,000 (22 cents), down 55 percent from $1.4 million (47 cents) in the comparable period of 1981.