The Federal Aviation Administration will require some users of Pratt & Whitney's geared turbofan engine to conduct ultrasonic inspections of a key part within 30 days, the agency said in an airworthiniess directive published Friday.

Pratt & Whitney parent RTX Corp announced in July that a "rare condition" in powdered metal meant 1,200 of more than 3,000 engines, built for the twin-engined Airbus A320neo between 2015 and 2021, have to be taken off and inspected for micro cracks that would point to fatigue.

The new airworthiness directive codifies the regulator's response to the previously disclosed problem.

RTX declined to comment on the directive.

(Reporting by Valerie Insinna)