Fairchild Industries Inc., the big Germantown aircraft and communications company, yesterday reported a 50 percent increase in second-quarter profits to $14.1 million from $9.2 million.

The gain in profits outstripped the improvement in Fairchild's sales, which climbed to $228 million from $183 million in the same period a year ago.

On a per-share basis, Fairchild's profits amounted to $1.10 in the three months ended June 30, up from the equivalent of 74 cents last year, after adjusting for a stock split.

For the first six months of 1980, Fairchild earned $24.5 million ($1.92 a share) on sales of $425 million compared with $16.8 million ($1.37) on sales of $339 million a year earlier.

Fairchild President John Dealy said the improved profits reflect "the continued strong performance of Fairchild's principal product lines" -- military and commercial planes, aircraft seats and components for commercial airliners.

During the quarter Fairchild delivered 36 a10 attach aircraft to the Air Force, six more than last year. First-half production of the A10 increased to 72 planes from 59. Fairchild's Swearingen Aviation Corp. in San Antonio, Tex., delivered 41 merlin executive turboprops and Metro commuter airlines during the first half compared with 32 in the same period a year ago.