A winglet separated in flight from a Cessna Citation CJ3 equipped with Tamarack Aerospace’s Smartwing active winglet system on Thursday evening. According to a statement from Tamarack Aerospace, the winglet broke off due to an as-of-yet unidentified “external cause.”

The 21-year-old aircraft, registered as N869AC by Minnesota Equipment Leasing, was on a flight from Anoka County Airport (KANE) near Minneapolis to Tampa International Airport (KTPA) with an intermediate stop in Walnut Ridge, Arkansas. The pilot was descending to Tampa when he experienced “bumps” and then noticed the left winglet was missing. He slowed the aircraft, declared an emergency, and landed without incident.

The approach and landing were filmed by the crew flying WFLA TV’s Eagle 8 AStar helicopter, which happened to be in the air when the incident happened. According to WFLA, “Officials at Tampa International Airport said a Cessna Citation was at 27,000 feet near St. Petersburg when the pilot lost the left winglet and part of the wing.”

Jacob Klinginsmith, Tamarack Aerospace Group president, said that certification flight testing for the company’s Smartwing modification included a “one winglet removed” scenario simulating birdstrike, lightning strike, “or any other abnormal event to the winglet.” 

“We are obviously grateful that nobody was injured in this strange incident,” he said. “We’re still investigating, but it appears that external factors caused the winglet to be ripped from the aircraft.”

The incident comes two months after Tamarack settled a lawsuit related to the 2018 fatal crash in Indiana of a CJ equipped with the company’s Smartwing Atlas (active load-alleviation system) winglets that killed all three aboard. The NTSB’s probable cause for that accident was “The asymmetric deployment of the left-wing load alleviation system for undetermined reasons, which resulted in an in-flight upset from which the pilot was not able to recover.”

Tamarack Aerospace, which was a party to the investigation, however, disagreed with the NTSB’s conclusion and filed a petition for reconsideration on Jan. 3, 2022, with the NTSB. The agency has yet to respond to the petition.

An incident with a Smartwing-equipped CJ prompted a worldwide grounding of aircraft equipped with the system and related EASA and FAA airworthiness directives, a subsequent 2019 bankruptcy filing by Tamarack, and a redesign of a component in the active winglet system. Tamarack exited bankruptcy in 2021. 

Tamarack winglets have been installed on more than 170 Citation CJ-series aircraft. The company is also developing winglets for the Airbus A320, King Air, and Ampaire’s series of electric-powered conversions that include the Cessna 208 Eco Caravan and Eco Twin Otter. 

Tamarack said its winglets add efficiency, alleviate the impact of turbulence, improve high/hot performance, shorten runway requirements, and increase payloads.