Every Wednesday, about 20 students at St Paul's Convent School gather inside a large classroom to drill holes and hammer nails into metal sheets that are parts of an aircraft measuring 6.46 metres in length, with a wingspan of 7.38 metres.
Under the guidance of Cathay Pacific pilot Hank Cheng Chor-hang, the project is now in its fourth year, and still awaiting the government's permission to be allowed to fly.
The aircraft they are building is an RV-8, a two-seater plane with a single engine and a top speed of 360km/h. It comes in a kit that buyers have to assemble themselves.
"Pilot builds full-scale aircraft with teens" Video by Hedy Bok
"I always wanted to build something," said Cheng, who has spent more than HK$1.4 million on the kit thus far. "I want to do it with secondary school students because I want them to experience something unusual, so they would have a better idea what to do in the future."
The final bill will amount to more than HK$2 million, taking into account fuel and delivery costs.
Cheng said some colleagues and friends from the engineering field and in the Government Flying Services were also helping in the project.
While it might be easier to partner with a university, Cheng said he favoured working with a secondary school. He was inspired by a similar undertaking at a technical school next to where he underwent pilot training in Adelaide, Australia.
He had approached other secondary schools before relatives recommended St Paul's in Causeway Bay four years ago.
Other schools turned down his requests, but St Paul's principal, Sister Margaret Wong, was more than happy to agree to the project, Cheng said. Starting in a small room on the sixth floor, the "aircraft factory" has now moved to a ground-floor space that is the size of two classrooms.
The aircraft's parts will have to be transported out of the classroom, and then to the airport for the final stage of assembly.
"I asked the principal how we could take them out of the classroom. She said to me, 'What's the problem? We'll just knock down the windows and slide the parts out to the street'," Cheng quipped, still surprised at the school's supportiveness.
Students participating in the project first went through a rocket building programme, and then learned basic aviation theory before joining the construction team. They practised on another kit before tackling the real thing.
"Every step is very important. We have to get every step right," Aileen Mok Ai-lam, a Form Six student, said.
Asked if they would want to have a tour on the aircraft, the students fell silent, then burst into laughter.
The project has had its share of bumps, however. At one point, the team mistakenly drilled an extra hole in the wing. Cheng then had to buy a new part and had it shipped to Hong Kong.
"It's actually not difficult to build a plane, in terms of skills. But it requires a lot of patience. You have to repeat one step again and again," Cheng said. "That's when the mistakes creep in."
Cheng, who studied aerospace engineering in the United States before receiving his pilot training, said he planned to donate the plane after doing a world tour for charity.