WASHINGTON (Reuters) - The Federal Aviation Administration said Tuesday it is investigating claims by a union that Boeing ( BA ) retaliated against two employees who in 2022 insisted the planemaker re-evaluate prior engineering work on 777 and 787 jets.

The Society of Professional Engineering Employees in Aerospace (SPEEA) said the two unidentified engineers were representatives of the FAA, which delegates some of its oversight authority and certification process to Boeing ( BA ) workers. The union filed an unfair labor practice charge with the National Labor Relations Board saying the two engineers had received identical negative evaluations after the incident.

Boeing ( BA ) did not immediately comment.