FAA Grounds Citation 525s With Tamarack Winglets

AD allows a ferry permit with flight restrictions.

Tamarack winglets
FAA is worried that further flight of aircraft with the affected Tamarack winglets could lead to a total loss of aircraft control.Courtesy Tamarack

The FAA today issued an airworthiness directive effective immediately that grounds all Cessna Citation CJ 525, 525A and 525B models operating with Tamarack active load alleviation system (ATLAS) winglets installed in accordance with STCSA03842NY. The agency said malfunctioning of the ATLAS could lead to loss of control of the entire aircraft.

The European Aviation Safety Agency issued a similar AD against Tamarack-equipped CJs last month explaining, "the active load alleviation system, when operational, deflects the Tamarack active control surfaces on the outboard wings. Recently, occurrences have been reported in which ATLAS appears to have malfunctioned causing upset events where, in some cases, the pilots had difficulty recovering the aircraft." EASA required operators to deactivate ATLAS and fix those control surfaces in place within 10 hours of flight. The European agency also added a number of operational limitations and repetitive pre-flight inspections to these aircraft. The NTSB is investigating whether Tamarack winglets played a role in the earlier loss of a Citation 525.

The FAA, however, does not allow Tamarack CJs to operate with the ATLAS disabled. The agency did not agree with the disabling solution provided by the STC holder, Cranfield Aerospace Solutions, for the use of speed tape around the Tamarack active camber surface to prevent movement. The agency said further flight would be unsafe because an operational ATLAS may reduce the pilot’s ability to control the airplane and hence should be grounded pending incorporation of an FAA-approved modification estimated to cost $175.

Until repairs have been made, the FAA is allowing a ferry permit on individual aircraft as long as no passengers are aboard. Until repairs are completed, the aircraft is also restricted to flight at FL250 or below and airspeeds not to exceed 140 knots on the 525 and 161 knots on the 525A & B models.