The European Union Aviation Safety Agency (EASA) has approved fixes incorporated in two previously issued Tamarack Aerospace service bulletins to resolve an emergency airworthiness directive that required deactivating Tamarack's active load-alleviation system (Atlas) on Cessna CitationJets, the company announced today.

Unlike conventional winglets, Atlas uses active load-alleviation tabs—called Tamarack Active Camber Surfaces (TACS)—to counter increased aerodynamic loading on those surfaces. In restricting the use of the winglet system, the EASA emergency directive issued April 19 had cited "occurrences…in which Atlas appears to have malfunctioned, causing upset events where, in some cases, the pilots had difficulty to recover the airplane to safe flight."

The fixes require that Atlas-equipped Model 525, 525A, and 525B aircraft operating in Europe comply with a new EASA service bulletin (SB1480) that encompasses two prior Tamarack SBs. Released in April 2018, SB1467 requires installation of a revised TACS control unit (TCU) to resolve instances of uncommanded TACS movement, while SB1475, issued earlier this year, calls for installation of aerodynamic centering strips to force those surfaces back in trail in the event of a TCU fault.

"I offer my sincere thanks to our loyal and supportive customers. They have been our staunchest advocates despite the inconvenience and hardship of having the use of their aircraft restricted," said Tamarack founder and CEO Nicholas Guida. "The resolution of the [emergency AD] is great news for Tamarack and its European customers."

An FAA airworthiness directive issued in late May remains in effect keeping Atlas-equipped jets grounded in the U.S., but company president Jacob Klinginsmith expressed confidence that agency would follow suit in approving the new SB. "EASA and the FAA have been meeting regularly and we anticipate that the FAA will offer a solution to the limitations very shortly, in the spirit of the bilateral agreement in place between the agencies," he said.