Flying them or fixing them, Mary Feik loves airplanes.

''I am an airplane nut,'' admits Mary Feik, the only female on the restoration team at the Smithsonian Institution's Paul Garber Facility, where the nation's historic planes are spit-and-polished for the Air and Space Museum in Washington.

She's also a machine nut who owns two airplanes and overhauls all her cars and home appliances. A member of the ''Ninety-Niners'' (an organization started by 99 female pilots, including Amelia Earhart), and of the Experimental Aircraft Association, Ms. Feik started this practice, she says, by restoring her first engine at the age of 13 - a Model A she and her father hauled out of a junkyard for $35.

''My father had a repair shop,'' she explains, ''and we were raised during the depression in a time when you had to help out to survive. As a preschooler, I remember having my own creeper to go under the cars and hand my dad tools. I was the tool manager,'' she says.

Then, as a newspaper office teletype operator at the outbreak of World War II , she read an article about the pressing need for mechanics to work on airplanes. ''I sent them pictures of my car before and after, and wrote asking if airplanes were much different from cars,'' she explains.

In fact, she says, they're lots simpler - ''cars are much dirtier, less reliable engines. In a car, the timing can be off and it can kind of jerk along. But you don't fly in an airplane if the timing is off.''

She first learned about this in the United States Army Air Corps, where, after a few weeks of training, she became an 18-year-old instructor, taking ''enlisted, noncommissioned officers and training them to be Crew Checks (those who decide what needs to be done to an airplane to make it fully operational),'' she says. ''Often, I didn't have anyone in class as young as I was, but it wasn't a problem - after the initial astonishment.''

The little gasp she hears when men see her working in ways nontraditional to women has followed throughout her career. Sometimes, of course, it's more than a gasp.

One of those times came during the war when she was sent to Wright Field as the first female engineer aide. There, she spent what she describes as one of the worst days of her life ''interviewing everyone to see if they'd give me a job (since ''engineer aide'' didn't fit any of their existing job descriptions). No one would, and I finally sat down in a hallway chair and almost cried.''

Then the senior engineer of the Special Weapons Division came over and asked the personnel officer if ''anyone had taken Mary on. He said something polite like, We haven't found just the right job for her yet, and John said - I'll never forget it - ... I'll take her. Then he marched me down the hall, put me in an office, and put me in charge of Fighter Pilot Transition Training.''

It was her job to design a training routine for pilots to learn high-performance combat training, a job that was greatly aided, she says, by her being allowed to go up in the various fighter planes.

First, though, she had to get permission to go - permission that was barred to women. The same division chief who hired her pointed out in a memo that the ''only thing standing in the way was the fact that I'm a woman,'' she says. ''Then they were forced to acknowledge it and had no choice but to let me fly.''

Her first day up was a classic case of ''initial astonishment.'' She called up Flight Operations early in the morning (when her voice tends to be low, she says), saying, ''This is Feik,'' and asking for permission to go up in a B-29. They checked it out on their roster and signed her up.

When she showed up for the flight, ''the crew just looked,'' she says with considerable amusement, ''and said, Is this Feik? They didn't know what to do with me,'' she recalls, laughing. ''There wasn't much conversation during the whole flight.''

She says she has tried to handle all the ''first woman ever'' situations she's found herself in by ''not making a big deal out of it, doing it quietly, nonchalantly. I did it by the book, too, so the only difference would be that I am a woman - they wouldn't have anything else to pin their objections on.''

But she says that in all her jobs she has learned to ''interchange talents'' with men. ''If there's something that requires a lot of small muscle dexterity, I'm always willing to help,'' she explains. ''And if I get out on the end of a 10-foot pipe and I can't budge a nut, I holler for help. But they know that if I'm asking for help, it means I've exhausted every other avenue first.''

She believes her work was appreciated at Wright Field, where she eventually became the first female engineer, until the end of the war. That was a time, she says, that was ''traumatic for women. We were coerced into believing that we should give up our jobs to men, that we were taking bread out of the mouths of families,'' she says. ''It was like they said, OK, you did a good job, we kind of appreciated it, now we don't need you, go home.''

She continued to work at Wright Field until the Korean war, she reports in her even, careful way, when she decided to ''help Bob (her husband) with his work.''

She helped raise their daughter, moved around the country (with her Air Force husband), and finally retired near Washington. ''The day Bob retired I bought my first airplane - a Piper Comanche PA 24-180,'' she says.

She volunteered to give tours at the Paul Garber Facility seven years ago (''it was sort of a natural thing for me to do''), after having taken part with a couple of airplane restoration teams and sprucing up her second airplane, a 32 -year-old Pacer PA 20-135. ''It still has the original fabric covering,'' she says with lights in her eyes. ''I'm very fond of fabric-covered airplanes; they can trace their origins back to the Wright brothers themselves, and there's something very tactile about working with them after all that cold, hard metal.''

Two years ago, the Smithsonian asked her to join the Garber staff as a special aide for VIPs, ''but it took me a year to decide if I really wanted to go back to work,'' she says. ''Finally, I decided it was such a compliment to be asked at all that I said yes.''

This year they allowed her to work at her real love - restoration. Together with another employee, she's restoring a 1909 Wiseman-Cooke airplane, ''one of the Early Birds. It's about 80 percent complete and ready for recovering'' - a fabric job she's looking forward to.

She also restores planes privately around the Washington area and finds time once or twice a week (''not enough!'') to fly. And if an airplane passes overhead, she's liable to stop the conversation and look up - ''I'm just crazy about airplanes!''