NTSB: Helicopter Crash Caused by Engine Failure, Lack of Routine Maintenance

Jan. 20—A routine engine inspection was two years overdue at the time of a deadly 2021 helicopter crash on St. Thomas, and corrosion or damage "could have been detected and addressed" by maintenance personnel before crucial engine components failed, according to the final investigation report by the National Transportation Safety Board.

The crash killed pilot and owner of Caribbean Buzz Helicopters, Maria Rodriguez, 55, and her three passengers, Daniel Yannone, 54; his wife, Neisha Zahn, 52; and son, Tyler Yannone.

Rodriguez had been flying the family on a 17-minute sightseeing tour of the west end of St. Thomas when the helicopter suddenly crashed into a densely wooded hillside in Botany Bay at around 3:15 p.m. on Feb. 15, 2021.

A preliminary investigation report had indicated that mechanical failure, not pilot error, caused the fatal crash.

But the final report goes a step further and places blame on maintenance personnel responsible for ensuring the helicopter was safe to fly.

The probable cause of the crash was identified as "A total loss of engine power due to fatigue failure of two of the stage 3 compressor blades," according to the report, which was published Thursday, nearly two years after the crash.

"Contributing to the failure of the compressor blades was the failure of maintenance personnel to inspect the compressor at the recommended interval for operation in corrosive environments," according to the report.

The NTSB also published various documents from the investigation, including more than 100 pages of photos and information about the crash site and the analysis by aviation experts.

Toxicology testing performed by the Federal Aviation Administration's Forensic Services Laboratory "identified no evidence of impairing drugs or alcohol" in Rodriguez's body.

The helicopter's location at the time of the engine failure also prevented Rodriguez, an experienced pilot, from performing a maneuver that could have cushioned the impact of the crash.

"The helicopter's proximity to the rising terrain at the time of the power loss likely precluded the pilot from performing a successful autorotation," according to the report.

Investigators examined the engine and "found evidence of fatigue fractures on two of the stage 3 compressor blades and fatigue fractures on the majority of the stage 6 compressor blades," according to the report.

The majority of the helicopter was consumed by fire after the crash, and heat damage made it impossible to determine whether the blades "were rubbing against the case and its plastic coating, which could have initiated the fatigue fractures," according to the report.

"Pitting corrosion" could have also caused the metal to fatigue and break, but there was no evidence of pitting found during the inspection, according to the report.

It also noted that the two stage 3 compressor blades broke off and were drawn into the remaining compressor stages, "resulting in the total loss of engine power in flight."

The engine maintenance manual called for more frequent inspections in humid environments in proximity to saltwater, like the Virgin Islands, which can cause metal to corrode more quickly.

"A caution within the 300-hour inspection table stated that the inspection must not exceed 300 hours or 12 months for coated compressor wheels, including the accident engine's stage 2-3 compressor wheel," according to the report.

Further, "the engine logbook showed that a 300-hour engine inspection was completed about 3 years and 800 flight hours before the accident. Paperwork associated with the two most recent inspections, conducted by the accident operator about 11 months and 1 month before the accident, respectively, did not indicate that the 300-hour inspection had been performed."

The investigation found that the engine logbook showed a 300-hour inspection was signed off on Feb. 15, 2017, and again on Jan. 11, 2018, "but a corresponding 300-hour inspection entry could not be found in either aircraft or engine logbooks," the reported noted, adding that the helicopter had previously operated in Alaska and Texas with other companies before arriving to St. Thomas on Nov. 26, 2019, for operation at Caribbean Buzz Helicopters.

"An undated engine inspection checklist from Caribbean Buzz Helicopters, possibly from the annual/100-hour inspection signed off on March 1, 2020, had no initials or markings in the 300-hour inspection section," according to the report.

The last annual inspection was signed off on Jan. 25, 2021, or three weeks before the fatal crash.

The report noted that "the engine inspection checklist's 300-hour inspection section was crossed out and marked 'N/A.' According to the operator's director of maintenance, the compressor case halves were not opened to facilitate visual inspection of the compressor section. Instead, only a borescope," a small extendable camera, "was used to inspect the compressor."

The report does not identify any of the involved individuals by name, including the director of maintenance, pilot, or victims.

The investigators concluded that the crash might have been prevented if the engine had been properly inspected.

"Had maintenance personnel completed the 300- hour inspection of the compressor case halves, blades, and vanes within the recommended 12-month interval, the presence of corrosion or damage to the plastic coating could have been detected and addressed," the report noted.

Rodriguez founded Caribbean Buzz Helicopters in 2011. She was honored in 2018 with the Helicopter Association International pilot of the year award, and Schneider Hospital officials unveiled a plaque in her honor at the Charaf Family Heliport in 2022. Rodriguez is survived by her husband and two children.

The passengers, Tyler Yannone and his parents Daniel Yannone and Neisha Zahn, were beloved members of the St. Thomas community, and Yannone was a senior at Antilles School at the time of the crash. — Contact Suzanne Carlson at 340-714-9122 or email [email protected].

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