Three Maryland men were injured yesterday, at least one of them seriously, in the unrelated crashes of two light airplanes, one in Montgomery County and one in Anne Arundel.

Robert Henry Aymar, of Glenwood, was seriously injured about 10:45 a.m. when his single engine aerosport, an airplane designed for home construction, crashed in a field near Damascus. County police attributed the crash to a loss of power.

Aymar was taken to Suburban Hospital with head injuries.

In the other crash, an antique single engine Aeronca crashed into the top of a stand of pine trees as the pilot was trying to land it at Schmidt's airfield in the eastern part of Anne Arundel, county police said. They blamed a crosswind for the crash, which destroyed the plane.

Pilot Daniel Rudd, 31, of Odenton, suffered a head laceration. Roy Denton, the passenger, was trapped in the plane after a tree branch passed through the plane's fuselage and entered his body.

Rescue workers climbed to the plane with ladders, sawed off the limb and lowered the victim with a block and tackle.He was listed in stable condition last night at the Shock Trauma unit of University Hospital in Baltimore.