John F. Dealy has resigned abruptly as president and chief operating officer of Fairchild Industries Inc., one of the largest corporations in the Washington area, and has accepted a settlement on his contract, which had 19 months to run.

The aerospace and electronics conglomerate based in Germantown announced Dealy's departure yesterday in a terse statement that pointedly omitted the words of praise and gratitude that normally accompany the departure of a veteran senior executive.

The statement said only that Fairchild's board of directors "expressed its appreciation for Mr. Dealy's 14 years of service to the company."

Dealy said his departure was by "mutual agreement" and declined to discuss the reasons for it. He said he does not have another job, but said he is confident that "other corporations can use my talents."

Dealy, whose contract guaranteed him a minimum annual salary of $160,000 in addition to fringe benefits, severed all connections with Fairchild and its subsidiaries and gave up his seat on the board, the announcement said. No reason was given for the unexpected move, and company officials declined to elaborate.

Edward G. Uhl, chairman and chief executive officer, also has taken on Dealy's duties as president, the company said.

Dealy, 42, a lawyer by training, was a key figure in several of the most important corporate developments that built Fairchild's annual revenues to about $1.2 billion. He engineered the establishment and development of Fairchild's American Satellite subsidiary and its partnership with Continental Telephone, and Fairchild's acquisition of Swearingen Aviation Corp. of San Antonio.

His departure took Wall Street by surprise because as recently as Jan. 27, he and Uhl had held a dinner meeting with analysts to discuss the company's prospects and promote its stock.

"I'm not sure this is going to be well-received," said Wolfgang Demisch, an analyst with Morgan Stanley Co. He said that Fairchild is developing new products and services that are a key to its future, and the decision to change managers in the middle is likely to create uncertainty among investors.

Fairchild stock , which has traded as high as $27 a share on the New York exchange within the past year, closed yesterday at $13.25, down 50 cents.

A hint of possible trouble came on Jan. 15 when Fairchild issued a preliminary report on its 1981 earnings. That report said that, although earnings for the entire year were expected to total $64.3 million, earnings for the fourth quarter would be only $4.6 million--that is, profits fell off sharply in the last quarter of 1981.

The report said that earnings were "adversely impacted by development and start-up costs on commercial aircraft programs." In particular, it said, Fairchild has "experienced difficulty" in starting production on the fuselage sections it is building for the new Boeing 757 passenger jet, the first of which is scheduled to fly later this month.

Spokesmen for Boeing said yesterday, however, that they had not encountered any problems with the components Fairchild is building at its Hagerstown plant and that the 757 development is on schedule.