Financially strapped Perpetual Savings Bank, the Washington area's largest savings and loan, yesterday named a new chief executive after federal regulators approved the appointment.

Perpetual named John Morton III, a former executive vice president of Maryland National Bank, to the chief executive post, replacing Thomas J. Owen, whose family has led Perpetual for decades. Owen, who is staying on as chairman, stunned the financial community when he announced in June that he would resign as chief executive.

The top-level changes at Perpetual followed an intensive review of the thrift by federal regulators, who must approve all major operating decisions pursuant to an agreement between Perpetual and the Office of Thrift Supervision.

Morton spent 17 years at Maryland National Bank before he was dismissed earlier this year as it pared its management ranks due to problems at the bank, sources said. In addition to becoming Perpetual's chief executive yesterday, Morton assumed the title of president. Earlier this year, Perpetual placed its former president, Ross C. Towne, on administrative leave.

A graduate of the U.S. Naval Academy and Harvard Business School, Morton spent nearly two de- cades at Maryland National Bank, where he worked on both consumer banking issues and large commercial lending transactions. Perpetual credited Morton with helping to expand Maryland National's market share and its presence in the metropolitan area.

Morton is a trustee of the Baltimore Museum of Art and treasurer of the Greater Washington Research Center, which analyzes the regional economy. During his time in the Navy, Morton served on a nuclear submarine.

Under the terms of Perpetual's agreement with federal regulators, Morton is expected to operate the savings and loan in a conservative fashion, emphasizing the traditional businesses of consumer lending and home mortgages. Perpetual recently ran into major financial problems, due in part to the risky commercial real estate investments it made in the 1980s.

Perpetual reported losses of $63 million on real estate loans during the first half of this year. Perpetual also said it may not be able to stay in compliance with regulations that dictate the amount of money it must reserve against potential losses.

Neither Morton nor Owen could be reached for comment yesterday. Perpetual spokesmen said they did not know where to reach Morton and that Owen was on vacation.

In a statement issued by Perpetual, Owen said Morton's "experience on both the deposit and lending side of the banking business {reinforces} our new emphasis on consumer banking."