Delta Air Lines is suing Pratt & Whitney, accusing the engine maker of breaching a parts agreement the Atlanta airline said could save it millions in repair costs.

The suit, filed this week in Fulton County Superior Court, said Pratt & Whitney refuses to recondition engine parts from planes Delta is retiring, parts that can be reused as spares.

Pratt & Whitney, an East Hartford, Conn.-based division of United Technologies Corp., has argued Delta has breached their contract by introducing parts from engines that aren’t in the original agreement. Delta wants the court to decide which side is right.

Delta spokesman Morgan Durrant said Friday there are no safety issues involved in the dispute, but he declined to comment further.

A spokewsoman for Pratt & Whitney said the court will resolve the issue. “Pratt & Whitney strongly disagrees with Delta’s claim,” Sara Banda said.

The dispute involves an original agreement that covered two engines, the Pratt & Whitney 2000 and 4000. The engines are in Boeing 757s and 767s. Delta said it can save an average $1 million per engine by breaking it down and using it for spare parts after a plane is retired.

Delta has sought to add more engines to the so-called “part-out” agreement, but the suit said Pratt & Whitney this year refused to accept additional parts as part of a side agreement.

The carrier has warned the engine maker it will use another supplier if it continues to refuse its parts. Pratt & Whitney said Delta itself would breach the agreement if it goes to another supplier. Their parts agreement runs through 2024, the suit said.

Delta said it is seeking reimbursement for the “unnecessary trouble and expense” Pratt & Whitney has allegedly caused.