The son and daughter of a North Carolina couple killed in a plane crash two years ago have sued the Spokane company that installed the aircraft’s engine and fuel-tank system.

The suit, filed Aug. 18 in Spokane’s U.S. District Court, asks for unspecified damages from Rocket Engineering Corp., which has been based in Spokane since 1989.

Plaintiffs Robert Bell III and his sister, Virginia Ellen Bell, allege that work done in 1999 on the small plane flown by their parents was negligent and contributed to their deaths.

Federal airplane accident records state that Robert Bell Jr., 61, and his wife, Andrea, 59, took off from Hilton Head, S.C., airport on Aug. 31, 2003, flying a Piper Malibu that belonged to a company the Bells owned and operated in their native North Carolina.

Robert Bell Jr. was the chief executive at Hickory Brands in Hickory, N.C., which manufactures and distributes shoe-care products.

Their plane had been refueled just before takeoff. Four minutes into the flight, Bell, an experienced pilot, radioed that he was returning for an emergency landing. Ground observers told investigators they saw gas spewing from one of the side gas tanks on the aircraft. Later, investigators found the loose cap from the left side fuel tank, according to accident records.

Bell crashed the aircraft about a mile from the runway, the accident report said.

The suit says Rocket Engineering crews, in February 1999, installed a turbine engine and other components. The lawsuit alleges Rocket installed a fuel system with a “defective” design that included a fuel tank cap that could be left in an unlocked position by anyone refilling the airplane.

Rocket’s attorney, Mark Steven Northcraft, of Seattle, said he hasn’t had time to prepare a formal reply to the suit. But Northcraft said it’s clear from preliminary research that Rocket Engineering is not responsible for the deaths.

“We will argue that pilot error contributed to the crash,” said Northcraft. “And it’s also likely that the (company) that refueled the plane before it took off has some responsibility.”

Robert Bell III lives in Hickory, N.C. Virginia Ellen Bell lives in Surfside Beach, S.C.

The amount of damages they’re seeking would be determined at a trial, the suit said.