F-35 Sustainment: Enhanced Attention to and Oversight of F-35 Affordability Are Needed, Statement of Diana Maurer, Director, Defense Capabilities and Management, Testimony Before the Subcommittees on Readiness and Tactical Air and Land Forces, Committee on Armed Services, House of Representatives [open pdf - 997KB]
From the Highlights: "The F-35 aircraft with its advanced capabilities represents a growing portion of DOD's tactical aviation fleet--with the Air Force, Marine Corps, and Navy currently flying about 400 of the aircraft. It is also DOD's most ambitious and costly weapon system in history, with estimated life-of-program costs exceeding $1.7 trillion. DOD plans to procure nearly 2,500 F-35s at an estimated total acquisition cost of just under $400 billion. The remaining $1.3 trillion in life cycle costs is associated with operating and sustaining the aircraft. This statement, among other things, assesses the extent to which (1) the F-35 has met warfighter-required mission capable rates; and (2) DOD has reduced the F-35's estimated life cycle sustainment costs and made progress in meeting its affordability constraints."
Government Accountability Office: https://www.gao.gov/