Dynalectron Corp., the McLean-based techological services firm, has named current President and Chief Operating Officer Merlon F. Richards to replace Charles G. Gulledge as the company's chief executive officer and vice chairman.

Richards' appointment is one of a series of executive changes, effective Nov. 1, that will follow the retirement of Gulledge, who will be 65 this month.

Richards, 64, joined Dynalectron in 1952 as a financial officer of Land-Air Inc., a major subsidiary. He was appointed Dynalectron's vice president for finance in 1959, senior vice president in 1972 and president in 1983.

Daniel R. Bannister has been elected president of Dynalectron, succeeding Richards. Bannister, 54, has served as executive vice president since 1983 and oversees the company's technical services activities, the second-largest segment of the company last year.

G. W. Walther Ewalt, executive vice president and manager of specialty contracting activities, the company's largest segment, has been assigned additional responsibilities to include the remaining operating divisions. Ewalt, 49, joined the firm 21 years ago and became head of its electrical and mechanical contracting business in 1973.

The area's 14th-largest company last year, Dynalectron had revenue of $538.5 million and earnings of $10.3 million.