January 12, 1986

A PERSISTENT fear that plagues buyers of existing homes - particularly older country or suburban houses - is that the houses may have hidden defects that could cost the newcomer thousands of dollars to correct. The fear is not unfounded. ''A used house is like a used car,'' noted Ronald Passaro, president of Res-I-Tech, a home inspection company in Weston, Conn., and a founder of the American Society of Home Inspectors. ''There is wear and tear, so there must be flaws.''

Airlines: The Fuel Factor Jet fuel prices are in a free fall - and for now, the airlines will profit. Since 1981, the fuel's price has dropped from $1.04 a gallon to 81 cents a gallon. This year, fuel could account for only 16 percent of airlines' operating costs - down from 31 percent in 1981 - if the price drops to 55 cents a gallon, as some of the most optimistic analysts predict. A penny drop in the price per gallon of jet fuel, says Mike Derchin, airline analyst for the First Boston Corporation, translates into about $110 million annually in operating profits. Does it mean lower air fares? It helps, says Timothy Pettee, airline analyst for L. F. Rothschild, Unterberg, Towbin. Cheaper fuel gives the airlines extra flexibility on ticket pricing, which they are using currently. Mr. Pettee calls the recent wave of carefully targeted fare reductions ''rational discounting'' -quite different from the savage price wars that hurt many airlines in the early 1980's.

The United States and Greece have signed an agreement for protecting military technology that opens the way for the sale of 40 F-16 fighter planes to Greece, a State Department official said today. The sale of two squadrons of the advanced planes had been pending for more than a year, the official said. The Administration's decision to go ahead with the sale followed Greece's agreement, worked out in the last several months, to sign what is called the General Security of Military Information Agreement, the official said. Worrying Over Greek Security The State Department official said there had been concern in the Administration, particularly at the Defense Department, over Greece's ability to protect advanced military technology from Soviet agents.

WITH new hearts beating vigorously in their chests, the first two patients to undergo heart transplants in New Jersey were peddaling stationary bicycles, eating solid foods and complaining of boredom last week. The two had dramatic back-to-back operations at Newark Beth Israel Medical Center on Jan. 1 and Jan. 2. ''They couldn't be doing better,'' said Dr. Jacques G. Losman, director of heart transplantation at the medical center and a former colleague of Dr. Christiaan N. Barnard, the heart-transplant pioneer, ''The operations proceeded without a glitch.'' The transplant team hopes a third donor heart will soon be available to save a 35-year-old woman admitted to the medical center last Monday. She developed severe heart disease two weeks after giving birth.

THE new Presiding Officer of the Suffolk County Legislature, Gregory J. Blass, said last week that he was elected despite the effort of a ''power elite'' to keep him out of the post, one of the most powerful in county government. According to Mr. Blass, a Republican legislator from Jamesport, the opposing faction included elected officials, political party activists and advocates for development projects who conceal their identity and intentions from the public. ''Much of what goes on in Suffolk County is the result of the efforts of this small and very clever group,'' Mr. Blass said. ''No one knows them all because they use money and power to shield their identities, but the script is always the same: to make as much short-term profit as they can and to make sure that no one else gets on top of their mountain. Long Island is their empire.'' Such provocative statements are typical of Mr. Blass, a 36-year-old lawyer who has made a career out of bucking the Republican leadership. But they take on added significance now that Mr. Blass has gained a foothold among that ''power elite.''