Tamarack Aerospace, the company under investigation following incidents involving aircraft it had modified, filed for chapter 11 protection earlier this month, Flying Magazine reported. The company, based in Sandpoint, Idaho, cited recent airworthiness directives issued by the FAA and EASA that had “effectively grounded” those Citation CJ1s, CJ2s, CJ3s and M2s equipped with its proprietary Atlas winglets. The winglets had promised to improve range, speed, and fuel efficiency for the Citation-series jets at a lower installed weight. The winglets came under scrutiny following several upset incidents in which pilots had to struggle to return to positive control. EASA issued its AD on April 19, stating, "Recently, occurrences have been reported in which Atlas appears to have malfunctioned, causing upset events where, in some cases, the pilots had difficulty to recover the aeroplane to safe flight." In the United States, the FAA issued its corresponding AD on May 24. While the EASA directive offered a temporary mitigation path involving use of speed tape to the secure the tabs, the FAA reasoned this was unacceptable, and grounded the jets in question outside of ferry flights.
