It also has Duncan Aviation Parts Support, an international organization that buys, consigns and sells general aviation parts.
Another achievement is its development of independent avionics and instrument test equipment.
The company describes itself as the most comprehensive aviation support operation in the world.
Most of its customers are high-end business aviators.
Those customers used to be the base of Duncan's triangle, a graphic representation of the three important components of the business, along with employees and the owners.
Now, and for some time, the base of Robert Duncan's triangle is the employees.
"We had it wrong," Robert said in an earlier interview. "If we take good care of the employees, they'll take care of the customers and we'll make money."
Simple, elegant and true, according to the trade press that covers general aviation.
"Yeah, but, yeah, but... many companies run that party line about the importance of employees," reported Vicki P. McConnell, technology editor of Aviation Maintenance magazine, in the August edition's cover story on Duncan Aviation. "The deal is, most companies don't put the level of dollars and cents into employee benefits as Duncan Aviation."
The magazine reported Duncan puts the equivalent of 20 percent of after-tax profits for the overall technical and professional education and development of the employees.
Duncan also has a policy of not laying people off.
"Everybody's got value, everybody's got something to contribute," Robert said. "That's a powerful thing."
Hundreds of employees have gone through leadership training, and Robert says it changes their lives, not just their work.
This is where the wing meets the air, responsibility arrives among happy people whose clients depend on them to keep their aircraft in the air, to stay alive.
"We're working with people's lives every day," Robert said. "Every single employee is responsible for safety. You have to have it. It's inherent in everybody's job.
"If they see something wrong, or a customer not being treated right, it's their responsibility to stop the process."
Among those whose education continues is son and successor Todd Duncan, 20 years with the company.
More than a year ago, he described himself as "vice president of something."
Now he's the chairman. He spent part of the summer living in a dormitory room at the Stanford Executive Program, no family, no car.
Todd said he read more and learned more than he imagined he could in six weeks.
Then, last week, as he succeeded his father, he was off to the annual convention of the National Business Aircraft Association in Atlanta. Last time, Duncan hung a huge umbrella with all its employees' pictures.
It was on December 5, 1963, that Donald Duncan incorporated Duncan Beechcraft-Lincoln. Though the name has changed, the number of locations has grown, and those 12 employees have turned into more than...
122 of the cuts are at from Michigan facility.
This summer, Duncan Aviation’s avionics satellite network celebrates the 25th anniversary of the opening of the first Duncan Avionics shop.