WASHINGTON—The FAA has ordered inspections of GE Aviation GEnx-1Bs and -2B fuel metering unit (FMU) parts after an improperly installed valve plug was linked to fuel leakage and an inflight engine shutdown on a UPS Boeing 747-8-F last July near Hong Kong.
An immediately effective airworthiness directive (AD) set for publication Feb. 22 gives affected operators of GE-powered 747-8s and 787s 150 flight cycles—roughly 90 days—to inspect FMU bypass valve plugs to ensure they are properly installed. The “shim check inspections” should be done with a 0.005-in. feeler gauge and can be accomplished either on- or off-wing, the AD said.
In the July 2021 incident, the UPS 747-8F was departing Hong Kong en route to Dubai when the crew experienced N1 overspeed and fire warnings, the AD said. The warnings, which occurred just after departure, led to an inflight shutdown of the No. 1 engine and prompted the crew to return to Hong Kong.
“After landing, the engine reignited and emergency crews extinguished the fire,” the FAA said.
An NTSB-led investigation found “several” fuel system leaks, including at the bypass valve pressure port, the FAA said. “The investigation concluded that the [bypass valve plug] might not have been torqued properly during production or during an engine shop visit,” the FAA said.
During the probe, GE Aviation learned that a 787-10 operator found a fuel system leak related to a loose bypass value plug during an August 2020 post-flight walk-around.
The manufacturer soon developed instructions recommending the inspection protocol and sent them out in December 2021 service bulletins. The FAA’s directive is based on GE’s bulletins.
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