Chief executives of the Fairfax Country government have about as much security as Charley Finley's managers for the Oakland A's.

Leonard L. Whorton, who was forced to quit by a dissatisfied majority on the Board of Supervisors last week, lasted a little more than two years. His predecessor, Robert W. Wilson, quit the job after three years when an election eliminated the comfortable liberal majority on the board with which he had a close relationship. Wilson's predecessor George I. Kelley Jr., served for about a year before angrily resigning during a public session of the board.

There is one remarkable exception to the short-times - Carlton C. Massey, who was named Fairfax's first chief executive in 1952 and continued in the position for 19 years.

Massey survived everything - even zoning scandals that touched the Board of Supervisors, but not him. So unchallenged was this Virginia gentleman, that when the county government moved into a new headquarters in 1969, the 12-story tower was christened the Massey Building.

The abrupt transition from the enduring Massey to his short-time successors occurred during some far-reaching changes in the Fairfax government. There seems to be a connection.

In Massey's day, the government was a relatively uncomplicated mechanism geared primarily to providing basic services (fire, police, sewer). When a supervisor wanted something done, he or she generally went directly to the appropriate department head - a practice Massey himself encouraged.

With such as arrangement, the county executive was not a lightning rod for thunderbolts hurled by supervisors when something went wrong.

Under the next county executive, Kelley, all that changed. The small, separate, departmental "fiefdoms and kingdoms" (his phrase) began to be subordinated under his office. When the supervisors wanted something, they went through Kelley first. When the departments churned out proposals, they were issued through Kelley.

The government began to grow phenomacally, but management-expert Kelley kept control of it.

Ironically, as the bureaucrasy was organised more tighly under Kelley, the supervisors acquires more overall authority because their reins were now attached to age horse.

In 1972, it appeared at times as if the horse were going in exactly the opposite direction it was being guided. While the board was trying to clamp more controls on growth, Kelley was presenting scenarios showing that more growth meant less costly public services. There were also differences over Metro: Kelley opposed takeover of the private Northern Virginia bus system while then board member Herbert E. Harris II and most of the other supervisors advocated it.

Kelley's undoing was his visit to Capitol Hill to oppose the bus system takeover.

The supervisors, having grown accustomed to pulling the reins while Kelley was executive, decided that they needed one who raced as fast but responded to direction.

The person they settled on was Robert W. Wilson, a Kelley protege whose low-key demeanor camouflaged his activist philosophy. In tune with the liberal majority, he was able to create a myriad of new programs and offices.

No one will ever know how Wilson would have meshed with the board that came to power in 1976. He resigned a month after the election.

In a sense, the board that was inaugurated in 1976 was more conservative than its predecessor. But as Supervisor Joseph Alexander (D-Lee) and others have remarked, the majority is a floating one. For example, Supervisor Marie B. Travesky, a Republican representing Springfield, often is aligned with some of the more liberal members.

It fell to Leonard Whorton to try to please this continuously reshaping majority. That was handicap enough. But Whorton was also an outsider, unfamiliar with nuances that can take years to recognize. A Carlton Massey would never have committed some of Whorton's gaffes (for example, preparing an analysis that, some supervisors felt, undercut the drive in the last session of the General Assembly to get a sales tax increase to aid county funding of Metro).

In addition to these problems, Whorton was trying to manage a bureaucracy that was far more complicated than any that existed in Massey's days. The government was no longer just a provider of basic services. It was now heavily involved in programs that are grouped under the label "human resources" - where expectations are high but progress is not always easy to measure.

Where land use once was the only burning issue, now there were a host of urgent problems: water supply, affirmative-action hiring, mounting taxpayer resentment (over assessments and location of group homes and subsidized housing, among other things) and a tax structure that wasn't flexible enough to deal with all county expenses.

All of these problems came to rest in Whorton's office. But while county executives since Kelley have acquired more direct responsibility, it is unclear how much additional power they have acquired to cope with the mounting burdens. The county executive is still appointed by the supervisors and serves at their pleasure.

In suburban Maryland, the county executives of Montgomery and Prince George's counties are elected and therefore can challenge their County Councils - though this system can lead to destructive impasses, as it has in Montgomery.

In choosing a replacment for Whorton, the supervisors probably will look closer to home, although considering the hazards of the job, there is not likely to be a large field of applicants.

If county executives continue to come and go, the supervisors, who are extremely careful about cultivating the image of their county, may have to examine their expectations - and that could be a painful exercise.