Operators of Rolls Royce-powered Airbus A330s face more frequent inspections of engine inlet cowls following a European Aviation Safety Agency mandate based on revised recommendations from Airbus.

The checks, first mandated in September 2011, focus on acoustic panels that line the inlet’s inner surface. Two cases of collapsed inlets linked to disbonding triggered the initial inspection requirements. EASA’s initial directive, based on a May 2011 Airbus service bulletin, called for detailed inspections, including a tap test, every 24 months following an initial inspection. Revised service information led Airbus to recommend cutting the interval in half, to 12 months.

Airbus in 2014 developed a modification that replaces the affected panels. While not mandatory, the upgrade is an option for terminating repetitive-check requirements. None of the in-service incidents have occurred on inlets that have the improved panels, EASA said.

FAA in 2012 issued an AD based on EASA’s original, 24-month repetitive-inspection requirement. The U.S. agency is likely to follow suit with a revised directive.