During the summer, a six-passenger, red-trimmed white helicopter landed on the 10-acre lawn frequently on weekends. The nearest neighbors could hear people volleying balls on the tennis court, splasing in the pool or Jacuzzi. Sometimes they would catch a glimpse throught the trees of the sailboat leaving the sleek modern boathouse or hear the speedboat, the fastest of its kind on the Chesapeake Bay, roaring off on an excursion.

But these days, builder developer Nathan Landow's Easton, Md., retreat -- where White House chief of staff Hamilton Jordan could escape for a little secluded "R and R" -- is seldom used by anyone.

Socially, Jordan has been keeping a low profile, and Landow's expensive little paradise of the Eastern Shore appears to have lost, for a while, its most prestigious VIP visitor.

"The man works hard," Landow says of Jordan. "He's under pressure. He can come down here and swim and take his work with him . . . read books, play tennis. It's better than when he works seven days a week and it's still dark when he leaves for the White House."

"I'm doing something nice for someone, and the whole country benefits," Landow says.

Once last summer, Landow says, Jordan came down for a party with the Democratic National Committee staff. Another time, Jordan "borrowed" the place and Landow wasn't there, he says.

One weekend, Jordan and another man called the Downs Cab Co. and rode into Easton with two young women in a 1962 Plymouth Valiant to have a steamed crab dinner at the Yesteryear Restaurant. Bob Higgins, owner of the Yesteryear, who has catered Landow's parties, says he was impressed with what "a well-behaved gentlemen" Jordan was.

Landow's neighbors compalined in writing about the noise from two parties that went on there till nearly dawn last summer. "that was my sons," Landow said, laughing. "They left the outdoor speakers on around the pool and went to bed, and the music boomed out down the river all night. I said, "Thanks a lot, fellas.'"

Landow says the five-bedroom, five bath house sounds "a lot more luxurious than it is. Down here on the Eastern Shore, the places are palaces. This was a model house for one of my apartments, and we moved it down from the construction site in sections."

Landow, who is Maryland State chairman of the Carter-Mondale Reelection Committee, says he is "happy" to loan the place to any friend who wants to use it.

"Lee Kling (former DNC treasurer who is now a Carter fund-raising consultant) called me from St. Louis to ask if he could use it to take his son duck hunting in November. I said he was welcome, and I'd line him up a good guide."

"I'll help when I'm called on," Landow said. "Bob Strauss said to me yesterday, 'I originally came (to the DNC) on an ego trip, but that was satisfied a long time ago.' The same is true of me."