(Bloomberg) -- The U.S. Air Force has delayed by four years a decision on whether the $44 billion KC-46 tanker program should be approved for full-rate production while contractor Boeing Co. tries to show it has fixed the flawed camera system used for the plane’s midair refueling mission.

An Air Force statement issued late Monday said the decision will come in July to September of 2024. It was previously planned for this September, Ann Stefanek, a spokeswoman for the service, disclosed on Tuesday.

The latest delay means the Air Force and lawmakers who provide funds for the troubled tanker will have an even longer wait before learning whether the aircraft put under contract in 2011 will be effective in its combat mission and can be maintained.

The Pentagon’s testing office wants to delay completion of ongoing combat testing and a congressionally-mandated final evaluation report until Boeing produces an improved, production-ready version of the “Remote Vision System” used by airmen to guide a refueling boom during the in-flight minuet to connect with another plane.

The Air Force said the delayed decision won’t affect orders to Chicago-based Boeing, which is already producing the KC-46 at a pace equal to full-rate production pace: 67 of the planned 179 are on contract, with 33 delivered.

Still, declaring full-rate production is supposed to be a Pentagon stamp of approval to taxpayers and foreign customers that a weapons system has demonstrated its combat effectiveness and that it can be efficiently produced and maintained.

Flight tests with the redesigned camera system are projected in 2022, with the improvements retrofitted on tankers already delivered in about July 2023, Jamie Burgess, Boeing’s vice president and program manager for tankers, told reporters in April. The 33 delivered tankers with the flawed system will need to be retrofitted.

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