An airworthiness directive published May 24 immediately grounded all Cessna Citations with Tamarack active winglets installed. The FAA noted that the NTSB is investigating whether a malfunction of the system was a factor in a fatal crash.
The FAA found the company’s response to reported malfunctions, including service information provided to owners, to be inadequate and unsafe, and ordered the aircraft grounded immediately.
The FAA specifically rejected the company’s proposed service information to disable the system—to use “speed tape” around each Tamarack active camber surface (TACS) to keep them faired in the neutral position during flight. The direct to final rule noted that any modifications mandated through AD action become changes to the type design and that the FAA would need to ensure that the use of speed tape complies with the applicable airworthiness regulations. The FAA determined that the speed tape does not have sufficient testing and analysis to support the type design change.
The FAA action follows an emergency AD issued April 19 by the European Union Aviation Safety Agency (EASA) requiring installed ATLAS systems to be deactivated, with the control surface fixed in place, along with imposition of operational limitations and a requirement for repetitive pre-flight inspections. The EASA directive cited multiple reports of “upset events where, in some cases, the pilots had difficulty to recover the aeroplane to safe flight.”
AOPA is examining the events and process that led to the EASA emergency AD and why it took the FAA five weeks to follow suit. Additionally, the association is reviewing the manufacturer’s subsequent actions, including existing and revised service bulletins, intended to mitigate the risk.
The FAA AD cited the EASA directive and additional information, including that the NTSB investigation of a fatal crash involving an ATLAS-equipped Cessna Citation in November “focuses on the role the ATLAS may have played in the accident. In addition to the accident, five incidents of aircraft uncommanded roll events with the ATLAS activated have been reported to EASA and the FAA. In each incident, the pilot was able to recover from the event and land the aircraft.”
A preliminary NTSB report on the Nov. 30 crash states that a Cessna 525A Citation was climbing through 6,000 feet when it “began a left turn, descended, and disappeared from radar.” The pilot and two passengers were killed in that accident; there were no survivors.
The FAA order grounds all ATLAS-equipped Cessna Citations “until a modification method is developed and approved,” allowing only a limited exception: up to 10 hours of flight under a ferry permit, with limitations on speed and altitude specific to the three Citations models for which ATLAS was approved and installed, and excluding carriage of passengers.
The FAA determined that the manufacturer’s service bulletin is not adequate to disable the system and address the safety risk:
“The FAA finds the service information from the STC holder (Cranfield Aerospace Solutions) does not contain adequate instructions to safely disable the ATLAS. Those instructions include the use of ‘speed tape’ around each Tamarack active camber surface (TACS) to keep them faired in the neutral position during flight,” the FAA emergency AD states. “The FAA would need to ensure that the use of speed tape complies with the applicable airworthiness regulations for use on a movable surface to hold that surface in a fixed position. The speed tape does not have sufficient testing and analysis to support the type design change. This program would involve testing for environmental effects, fatigue analysis, and analysis of hazards due to potential failures of the tape. Without more analysis, the security of the speed tape method to prevent movement of the TACS cannot be assured, and loss of control of the airplane may occur with the ATLAS disabled.”
The FAA estimated that the emergency AD applies to 76 aircraft in the U.S. registry; a company official told AOPA May 7 that ATLAS systems have been installed on more than 90 aircraft worldwide to date, and all but a few have been modified under the STC as amended in March.
“This AD prohibits flight until the incorporation of an FAA-approved modification. At this time, a modification does not exist; therefore, we have no data to use for estimating the cost of the modification,” the FAA wrote.
AOPA has reached out to Tamarack Aerospace and the General Aviation Manufacturers Association to better understand the issue, inform our review of the AD and future comments, and explore solutions and next steps to resolve the issue and return the aircraft to operation.