Monday, October 03, 2022

NTSB: Tamarack winglets likely caused plane crash

Staff Writer | November 9, 2021 1:00 AM

Editor's note: This story has been updated to include the correct location of the plane crash, and further clarifies Tamarack's explanation for the crash.

SANDPOINT — The cause of a 2018 Cessna Citation plane crash in Clark County, Indiana, was likely caused by modifications to the aircraft by Sandpoint-based Tamarack Aerospace Group.

Those findings were “strongly disputed” by Tamarack officials following the report’s release.

According to a final accident report by the National Transportation Security Board, the cause of the fatal crash that killed three people was caused by the Active Technology Load Alleviation System. ATLAS 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.

“The main components of ATLAS consist of two wing extensions and two winglets with an ATLAS control unit,” NTSB officials said in the report.

The malfunction came from the left Tamarack Active Camber Surface. The NTSB report alleges that the left TACS became inoperable shortly into the flight. It was stuck “trailing edge up” on the left wing side “for reasons that could not be determined.”

Because ATLAS is an after-market modification, it is not built into the plane it’s attached to, and does not have any internal recording devices. This is not the only time ATLAS systems have experienced this particular issue.

“The investigation found that five uncommanded roll incidents have been reported to either the European Union Aviation Safety Agency or the Federal Aviation Administration involving airplanes equipped with ATLAS,” the report said.

“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 said Thursday. “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.”

Tamarack engineers go on to specify the inconsistencies, saying that the aircraft was rolling when the autopilot automatically disconnected at a 30-degree bank angle, instead of the typical 45-degrees — which is usually what happens when Cesna Citation aircrafts go into an uncommanded roll.

Tamarack officials call the investigation into question, saying that the NTSB report fails to explain or address why the autopilot function stopped when it did. Officials went on to say the basic issue is that the autopilot clicked off before it was supposed to, raising the distinct likelihood that that malfunction caused the accident.

However, NTSB’s report noted that the Cessna Citation’s Aircraft Flight Manual is supposed to alert a pilot to a 55-degree bank angle at elevations over 2,450 feet.

Even though the plane was slanted enough to throw off a person’s balance, the pilot did not notice, according to the NTSB report, the pilot was distracted by an in-flight checklist. The slant would have been visually noticeable if the horizon had not been obscured by the clouds hanging below.

The flight lasted for three minutes thirty-two seconds and crashed eight-and-a-half miles northwest of Clark Regional Airport near Jeffersonville, Indiana.

The first alert came while the plane was at 6,100 feet making its initial climb. According to the audio recording from the cockpit, the pilot didn’t say anything for about 15 seconds after the alert. Then, the pilot shouted three expletives followed six seconds later by a mayday call.

“Mayday mayday mayday citation five two five echo golf is in an emergency descent unable to gain control of the aircraft,” said Andrew Davis, 32 at the time of the crash.

Those were Davis’s last words, according to records found. Also deceased in the crash were Wayne Estopinal, 63, and Sandra Holland Johnson, 54.

The event lasted 35 seconds from first alert to crash-landing. The plane was not required to have a flight data recorder, so there is no other source of data from the crash. The ATLAS “inoperation button” was not recovered in the wreckage.

“Tamarack extends its deepest condolences to the families and friends of those who died in the 2018 tragic accident,” company officials said, “Tamarack intends to request the NTSB reconsider its finding, as per its own procedures. Tamarack will provide a more detailed response after further consideration of the NTSB’s recent announcement.”

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