Tamarack Aerospace announced that the FAA has approved an alternative method of compliance (AMOC) that will return Cessna CitationJets equipped with the company’s active load alleviation system (ATLAS) winglets to service once “all existing product improvements” have been incorporated. The modifications, which are described in EASA Service Bulletin SB1480, include fixes to improve reliability of the Tamarack Active Camber Surface (TACS) Control Unit and add centering strips to “aerodynamically force the TACS back to their faired position” in the event of a system fault. FAA approval of the AMOC follows similar action taken by EASA last week. The aircraft have been grounded in the U.S. since May.
“The AMOC is an intermediate step meant to provide a way for the affected CitationJets to fly sooner than waiting for the final resolution of the AD, which will come later,” Tamarack said in a press release. “Its provisions allow all US registered aircraft in compliance with Service Bulletin (SB)1480 to fly again without the AD’s restrictions.”
As discussed in a podcast with Tamarack’s Jacob Klinginsmith, Tamarack service bulletins including the modifications presented in SB1480 were issued prior to the FAA AD. According to Tamarack, 89 of the 91 ATLAS-equipped aircraft in operation are already in compliance. As previously reported by AVweb, Tamarack Aerospace Group declared bankruptcy in June as a result of the grounding.
The AD (PDF) grounding the aircraft was issued on May 24 following an April 19 mandatory continuing airworthiness information (MCAI) order from EASA. The AD stated that five incidents of “uncommanded roll events with the ATLAS activated” were reported to the FAA and EASA. The NTSB is also investigating the fatal accident of an ATLAS-equipped 525A that occurred in Clark County, Indiana, on Nov. 30, 2018. Although the investigation is ongoing, the AD states that the NTSB is focusing on the role the ATLAS may have played in the accident.