F-35 Joint Strike Fighter: Cost and Schedule Risks in Modernization Program Echo Long-Standing Challenges, Statement of Jon Ludwigson, Director, Contracting and National Security Acquisitions, Testimony Before the Subcommittee on Tactical Air and Land Forces, Committee on Armed Services, House of Representatives [open pdf - 627KB]
From the Highlights: "The F-35 Lightning II Joint Strike Fighter program began development in 2001 and remains DOD's most expensive weapon system program. Currently, the program is more than 8 years delayed and $165 billion over original cost expectations. As the program progresses toward completing operational testing of the aircraft's baseline capabilities, it still faces risks. DOD is also 3 years into an effort, called Block 4, to modernize the F-35 aircraft's capabilities. Block 4 is loosely based on Agile software development processes. With this approach, DOD intends to incrementally develop, test, and deliver small groups of new capabilities every 6 months. This testimony discusses acquisition-related risks in the F-35 program."
Government Accountability Office: https://www.gao.gov/