"We testified that DOD faces challenges keeping the growing [F-35] fleet ready to perform its mission, largely due to insufficient planning", the report said. "Challenges include spare parts shortages: F-35s were unable to fly about 30 percent of the time due to a lack of spare parts from May-November 2018, poor performance of the information technology system used to sustain the aircraft: It requires manual workarounds and has data inaccuracies".
The report comes amid the US and Turkey dialogue about Turkey's purchases of Russian S-400 air defence systems and American F-35 fifth-generation fighters.
In July, the United States announced its decision to suspend Turkey's participation in the US-sponsored F-35 fifth-generation fighter programme over Ankara's S-400 deal, adding that the country would be completely removed from the project by late March 2020. The US has repeatedly objected to its NATO ally purchasing the S-400, claiming that the system is incompatible with the alliance's security standards and might compromise the operation of F-35 jets.
Lockheed Martin’s F-35 is a fifth-generation stealth multirole fighter. It is considered the most expensive weapons program in history, with a projected life cycle cost of between $1 trillion and $1.5 trillion, according to published reports.