The FAA issued an airworthiness directive (AD) on Friday grounding Cessna CitationJet 525, 525A and 525B models with Tamarack active load alleviation system (ATLAS) winglets installed until a modification can be developed and approved. The FAA says the AD (PDF) is the result of mandatory continuing airworthiness information (MCAI) issued by the European Aviation Safety Agency (EASA) on April 19, 2019. According to the AD, “five incidents of aircraft uncommanded roll events with the ATLAS activated have been reported to EASA and the FAA.”
The NTSB is also investigating a fatal accident involving a 525A with the ATLAS STC installed that occurred in Clark County, Indiana, on Nov. 30, 2018. Three people were killed in the crash. Although the investigation is ongoing, the AD states that the NTSB is focusing on the role the ATLAS may have played in the accident. Investigations into the causes of the uncommanded roll incidents are in progress as well.
Although EASA is allowing operation for up to 100 flight hours with the system disabled—with operating limitations—the FAA AD prohibits further flight until a solution can be developed. According to the FAA, “the service information from the STC holder (Cranfield Aerospace Solutions) does not contain adequate instructions to safely disable the ATLAS.” The AD further specifies that the aircraft owner or operator may revise the aircraft flight manual (AFM) and fabricate and install a placard prohibiting flight. The FAA says that 76 U.S.-registered aircraft will be affected by the AD.
The AD is effective immediately and will be open for public comments until June 8, 2019.