National Transportation Safety Board officials have revised a ruling that said a Tamarack winglet was at least partially to blame for a fatal 2018 aircraft accident in Indiana.

“… the available evidence for this accident does not sufficiently show that the ATLAS was the cause of the in-flight upset from which the pilot was unable to recover,” NTSB officials said in the agency's formal response to Tamarack's appeal of its initial ruling.

In its initial ruling in 2021, NTSB ruled a fatal 2018 Cessna Citation plane crash in Clark County, Ind., was likely caused by modifications to the aircraft by Sandpoint-based Tamarack Aerospace Group.

Those findings were “strongly disputed” by Tamarack officials, and the Sandpoint company filed a formal appeal of the ruling in January 2022.

The company's petition cited multiple factual errors in the NTSB final report, contending its conclusion were not be supported by the facts of that accident. 

Tamarack applauds the NTSB for studying the objective and verifiable facts and data available and using correct information to revise the probable cause, Jacob Klinginsmith, Tamarack president said.

“Tamarack is very pleased that the NTSB has decided to grant our petition for reconsideration concerning this 2018 accident and taken steps to correct multiple technical errors in the original investigation," Klinginsmith said. "This reversal shows the NTSB has the courage, professionalism, and proper process to make these corrections, and for that we applaud the NTSB."

While the agency does not normally consider petitions that repeat previous arguments, the agency agreed to make an exception due the Tamarack Aerospace officials assertions that the finding were erroneous and did not include all its submitted materials.

In its revised ruling, the NTSB agreed with Tamarack "that the evidence is also insufficient to conclude that (1) the left actuator was in an extended position at the time of initial impact and (2) the ATLAS caused the left rolling moment; the NTSB has revised the report accordingly.”

Tamarack Aerospace officials said they were pleased with the agency's decision to reconsider its initial ruling, and with its finding that there was insufficient evidence that its winglet system was to blame.

The Active Technology Load Alleviation System winglet system is an after-market modification where an upturned metal extension is placed on the aircraft’s wing tips to assist in fuel mileage and reduce turbulence.

Tamarack officials called the agency's investigation into question, saying that the NTSB report failed to explain or address why the autopilot function stopped when it did. They said their review showed that the autopilot clicked off before it was supposed to, raising the likelihood that that malfunction caused the accident.

“We disagree with the NTSB’s final report that concludes active winglets installed on the aircraft N525EG were the probable cause of the accident,” Tamarack officials after the initial ruling. “The forensic evidence collected in the investigation indicates that the load alleviation system was indeed operational. There are inconsistencies within the report that do not support the conclusion published by the NTSB.”

While the company disputed the agency's initial ruling and Tamarack officials are pleased the NTSB revised its ruling, Klinginsmith said their thoughts are with the families and friends of those who lost their lives. The hope is that the new conclusions can bring closure to the prolonged investigation, he added.

In early 2023 Tamarack Aerospace Group reached a confidential resolution of all claims related to this mishap. Tamarack remains dedicated to enhancing aviation safety.