European regulators have lifted an emergency airworthiness directive for Tamarack Aerospace's Atlas active winglet system fitted on certain Cessna Citation light business jets.

A solution to the issue has been found that improves the reliability and safety of the aircraft, says the Sandpoint, Idaho-based company.

The European Union Aviation Safety Agency (EASA) approval – via a supplemental type certificate amendment, attached to a service bulletin (SB) – clears the way for modified aircraft to fly unrestricted throughout the bloc. The US Federal Aviation Administration (FAA) is expected to approve the fix shortly.

Tamarack CJ1


EASA and the FAA issued the airworthiness directives in earlier this year after Atlas – a load-alleviation system – malfunctioned on several occasions, causing in-flight upsets from which pilots had difficulty recovering the aircraft to a stable attitude.

Both regulators imposed drastic operating restrictions on Citation Jet, CJ1, CJ2/2+, CJ3/3+ and M2 aircraft equipped with the modification, and the debacle forced Tamarack into Chapter 11 bankruptcy protection.

Tamarack's solution calls for replacement of a screw inside the Tamarack active camber surface (TACS) control unit. This screw, it says, had previously been able to work free of its fastening structure and drive uncommanded movement.

Aerodynamic centring strips must also be installed to the upper and lower trailing edge of the TACS. “In the unlikely event of a system fault, the centring strips aerodynamically force the TACS back to their faired position, reducing the impact of the fault,” says Tamarack.

“We are pleased that EASA has agreed that these improvements address the safety concern that prompted the [airworthiness directive],” company president Jacob Klinginsmith says.

He adds that safety authorities “have been meeting regularly”, and the company anticipates that the FAA “will offer a solution to the limitations very shortly, in the spirit of the bilateral agreement in place between the agencies”.

Tamarack has secured “several active winglet sales with the restrictions in place”, Klinginsmith says. “As they are lifted, we can look forward to sales being much stronger, and we plan to emerge from Chapter 11 later this year as a strong and viable company.”

Source: Flight International