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An AW189 on oil field work with Bristow Helicopters in
flight from Norwich Airport, U.K.

The FAA is ordering the inspection of four Leonardo AW189 helicopters in the United States to check for a cracked tail gearbox fitting.

The U.S. presence of AW189 helicopters is limited to the four at Milestone Aviation Group and AAR Airlift.An FAA Airworthiness Directive issued last Friday and effective Oct. 26 "requires inspecting the tail gearbox fitting for a crack."

A crack in the TGB fitting could "reduce the tail assembly's ability to sustain loads from the TGB and the tail rotor and result in loss of helicopter control."

Lynn Lunsford, a spokesman for the FAA in Fort Worth, Texas, said that Leonardo personnel are to conduct the inspections, but had no further comment.

The FAA directive occurs more than two years after the European Aviation Safety Agency (EASA) issued a directive on the same issue.

"EASA advises that this condition, if not detected and corrected, could lead to crack propagation up to a critical length," the FAA directive said. "This condition could reduce the assembly's ability to sustain loads from the TGB and tail rotor, possibly resulting in reduced helicopter control. The EASA AD consequently requires repetitive inspections of the fitting and replacing the fitting, depending on the inspections' outcome."

The FAA said that it issued its directive "because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist or develop on other helicopters of these same type designs and that air safety and the public interest require adopting the AD requirements as proposed."

The FAA declined to comment when asked for an explanation behind the two-year lag between the issuance of the EASA airworthiness directive on the AW189 and the FAA airworthiness directive.