Boeing Company (BA) engineers union rejected a proposed contract and authorized a strike, potentially complicating the planemaker's certification of its delayed 737 Max 10 and 77X models, Bloomberg reported Friday.

A majority of members in SPEEA's professional and technical unit voted against the contract and in favor of strike authorization, Bloomberg said.

The union will survey members on what they would need to accept the proposal, the report said.

SPEEA represents engineers, scientists, pilots, technicians, analysts and other professionals at Boeing across five states, but does not represent production workers, Bloomberg said.