The Defense Department plans to ramp up production of the Lockheed Martin F-35 Joint Strike Fighter despite serious sustainment issues that have drawn out repair times and grounded jets, according to a recent government watchdog report.

Jets could not fly 22% of the time between January and August in 2017 due to spare parts shortages, according to a Government Accountability Office report released this week. Depot repairs are six years behind schedule, precipitating an average parts repair time of 172 days, twice the programme’s objective. Parts procurement takes two to three years, including a lengthy contracting period followed by additional time to produce parts.

Although former Joint Programme Office executive officer Lt Gen Christopher Bogdan had reined in the JSF’s ballooning costs, sustainment is still projected to cost the US Air Force, Navy and Marine Corps an estimated $1.12 trillion over a 60-year life cycle. Last February, Lockheed scored a $1 billion contract for F-35 logistics and sustainment services. But the GAO report warns that the programme’s concurrency strategy will stretch its resources to meet both development and maintenance needs at once.

The US Marine Corps offered a preview of sustainment problems to come. The USMC and US Navy plan to deploy the F-35 on its ships after 2018, but will do so without needed maintenance at sea. Meanwhile, the programme continues to struggle with delays on the Autonomic Logistics Information System (ALIS), a complex sustainment system resented by some international F-35 partners.

The Pentagon already sustains more than 250 F-35s, with plans to triple the fleet by the end of 2021 and field 3,200 aircraft globally over the programme’s lifecycle, GAO states.

But the US government appears unprepared for that impending ramp up as it grapples with repairs on a few hundred jets and jockeys with Lockheed over intellectual property rights that could ensure future competition for sustainment.

Long after Lockheed completes its deliveries, the programme will continue to face sustainment issues since the Pentagon has failed to identify all the technical data needed from the prime contractor to ensure weapons system performance and support.

“In 2014, we recommended that the programme office develop a long-term intellectual property strategy to include the identification of all critical technical data needs and their associated costs,” GAO states. “As of September 2017, the programme has taken some steps to develop an intellectual property strategy, but it has not identified all critical needs and their associated costs.”