GAO report:
Some highlights:
* If TR-3 is not qualified in April 2024 (I havent heard that it was) then in June 2024 Lockheed Martin will exceed their maximum capacity for parking undelivered F-35's at its various production facilities. The exact number of currently undelivered aircraft is classified. LM claim they can inspect and deliver 20 aircraft a month once the change to TR-3 is approved but the highest previously achieved monthly inspection and delivery rate was 13, even if it achieves its claimed delivery rate it will take over a year to fully clear the parked backlog.
* P&W did not deliver any new engines to the F-35 Assembly lines on time in 2023 with an average of each engine being 2 months late, an increase from 97% late with an average of 1 month delay in 2022. This isnt really affecting production though due to the delays in TR-3 causing a delivery backlog.
* Test fleet consists of four aircraft that are all over 10 years old and experiencing maintenance issues, one has been long term out of service so they are behind on weapons integration work, again due to being unable to test the new TR-3 software this isnt impacting the schedule too severely but a backlog of integration work is building up that will all hit at once once TR-3 is approved. To alleviate this they are building 4 additional test aircraft which are semi-instrumented and will be available from 2026 while a complete fleet renewal of 9 instrumented test aircraft is planned for delivery between 2029 and 2034 in batches of 3 (6 ordered so far) though this will leave a gap in 2028 & 2029 where no fully instrumented test aircraft are in service.
* Engine cooling upgrade is required from 2029 when planned post Block 4 capabilities will start requiring it however its not planned to be in service until 2030 with 2032 a more realistic in service date.
* New problem, the F-35C landing gear drag brace is experiencing more force during landings than it was originally designed for which could lead to a landing gear collapse, after 1300 landings it should be inspected every 200 landings until a permanent fix is developed.
* The issue with cracking of the panels around the F-35A internal gun due to pressure experienced on earlier lots has returned, this isn't due to FOD. The panel should be inspected for cracks everytime the gun has been fired, a replacement more durable panel will be live fire tested during 2024.
* The EOD window panel is experiencing poor durability in sandy environments (I thought this panel was made of factory grown sapphire!!??). Work to qualify a replacement window will take place in 2024.
* Some F-35 canopies across all models have experienced delamination of the external coating. A temporary fix was implemented in 2019 with a canopy vent hole to reduce pressure difference between layers but too small to de-pressurise the cockpit. In 2022 a secondary canopy supplier was qualified for A and C models and they are looking to qualify a secondary supplier for B models during 2024.