GAO Reports Highlight New F-35 Deficiencies

The Government Accountability Office released two companion studies dated April 25 that paint a stark picture of the F-35’s technical health and budget outlook. The auditors describe a fighter still haunted by fresh defects even as procurement ramps up. They note that a jammed main fuel-throttle valve can lock the engine at full power and fling the jet forward until the pilot shuts everything down. Test crews first spotted the surge during carrier workups in late 2017, and engineers have yet to seal the fix.

Cost lines keep climbing. GAO pegs development spending at $64.7 billion and says another $714 million is needed to close the baseline effort. Unit cost for all variants averages $143.8 million in FY-18 dollars—roughly three-quarters above the 2001 estimate. The United States has already signed for 359 aircraft at a price of $68.9 billion, while the total buy of 2,097 airplanes is set to drain $216.5 billion.

Production tempo hides quality gaps. By January 2018 the line had delivered 266 fighters, yet inspectors soon halted hand-overs for a month when they found bare metal under skin panels that were supposed to be primed. The repair bill is open-ended because no one knows how much structure must be stripped and resealed. GAO lists other risks: radar assemblies arrive late, canopy transparency batches fail acceptance shots, and wheel-tire units on the F-35B shred after short runs on coarse strips.

Program managers say Autonomic Logistics Information System (ALIS) will knit the global fleet together. GAO counters that ALIS breaks down when bandwidth stutters, takes hours to reboot in cold weather, and demands air-conditioned shelters that defeat plans to scatter jets on forward strips. Marines who ferried the first F-35B squadron to Japan routed ALIS servers through Hawaii because they feared Alaskan cold would brick the drives.

Pilots face cockpit hazards that remain under review. Some Air Force crews at Luke AFB reported oxygen-deprivation episodes; investigators have not traced a single root cause. Carrier pilots in the F-35C still endure violent catapult shakes that blur displays, and the panoramic helmet visor blooms green light during night landings and masks deck cues. Each issue demands a design tweak that piles fresh retrofit hours on jets already fielded.

GAO warns that risk stays high until operational testing winds down in 2019. The auditors expect more discoveries because flight sciences trimmed test points to keep the calendar moving. The Navy nonetheless aims to declare initial operating capability for the F-35C in August 2018, even though the final exam will run into the following year. That overlap forces the service either to start combat prep on provisional software or slip the date.

The second GAO paper, released the same day, tracks how lessons from the first Marine Corps deployment circle—or do not circle—through the joint community. Investigators found the Corps stored maintenance logs in unsecured commercial cloud accounts while ALIS links lagged, a workaround that left sensitive data exposed. They also note supply chokepoints: a twelve-hour wait for spare radar modules during Red Flag 2016 and an unexpected shortage of fiber couplers when jets dispersed across Okinawa during exercise Steel Knight.

The auditors list operational hurdles in plain language:

• ALIS needs constant network contact; when links drop, mission-planning tools crash and crews must manually rebuild flight loads.
• Classified tents that shelter servers require stable power and chilled air yet often deploy to bare pads where a diesel generator struggles under the heat load.
• Frozen screens, laggy logins, and corrupted data files remain common, forcing maintainers to double-enter tasks on paper.
• Each squadron hauls at least two forty-foot containers of ground gear because base stocks rarely match part demand.

These details undercut the marketing pitch that the F-35 can sprint off hidden strips with a lean tail. Even a single-day surge into rough territory drags along palletized air-conditioning units, satellite dishes, and stacks of special tires.

Other technical notes stack up. Marine pilots report the gun pod vibrates under rapid fire and shifts aim point. The C model’s wing fold hinges need tighter bushings after repeated salt-spray cycles. Fuel dumps during hot refuels spray onto the fuselage and peel low-observable coatings faster than expected. None of these quirks alone grounds the fleet, but each one adds downtime and expense.

GAO stresses that late fixes cost more because prime contractor Lockheed Martin must re-engineer tooling and send mobile teams across five continents to touch jets already in service. The watchdog says this “concurrency tax” was avoidable had the Pentagon held production until test work closed. Program leaders reply that concurrency saved time and cemented industrial skill early, yet they concede retrofit labor now rivals new-build labor on particular zones such as the wing root and inlet chines.

Analysts also highlight a gap between promised and delivered mission-capable rates. The Air Force seeks 80 percent, the Navy 69 percent, and the Marine Corps 75 percent, but GAO notes the entire fleet averaged barely 55 percent in 2017. High part cannibalization and depot backlogs drive most downtime. Engines rotate three times faster than forecast because hot climates push thermal margins; that churn leaves squadrons short on power plants during peak flying windows.

Money questions dominate briefings to Congress. The program office wants an open-ended follow-on modernization track called Block 4. GAO says the office has not locked requirements and risks chasing new capabilities before it finishes the old to-do list. Legislators already worry that Block 4 will stack another $10 billion onto a project that started as a low-cost “joint” venture.

Byline deep-dives aside, the single thread that runs through both GAO reports is uncertainty. Test pilots discover new corners of the envelope each month, and each corner hides an unplanned design tweak. Steel in factory jigs bears workmanship stamps marked 2013, but upgraded spares destined for those airframes carry 2018 mod codes, creating mix-match inventory headaches. The sheer scope of the rework wave prompts GAO to urge the Pentagon to slow new signatures until fixes stabilize.

Congressional aides say the message resonates across both chambers. One Senate staffer tells this site that the throttle-valve hazard “should have ended any talk of full-rate production this year.” House Armed Services members share that view and add that corrosion surprises suggest the finish system still lacks tight process control.

Lawmakers who traveled to Hill Air Force Base in March 2018 saw hangars packed with jets stripped of paint around fastener lines; those panels now await fresh primer before reassembly. Support officers warned that every hour spent sanding stealth edges steals hours from flight training. GAO captures the same story in sterile charts: growing sustainment cost, sliding readiness, dense supply lines.

The inaugural reports reach a clear bottom line: the F-35 remains a work in progress more than sixteen years after first flight. Each page unpacks evidence that the fighter’s promised affordability has slipped and that technological edge must be weighed against mounting life-cycle bills.

---

WHAT’S NEW  –  March 2025 Update

Almost seven years have passed since these GAO alarms first hit print, and the program still walks a tightrope. Lockheed Martin has completed more than 1,080 airframes, but a freeze on deliveries from July 2023 through August 2024 underscored how fast momentum can stall. The pause stemmed from Technology Refresh 3, a package of new core processors, panoramic displays, and memory cards that underpin Block 4 weapons. When a circuit-board supplier missed throughput targets, the assembly line slowed, finished jets rolled to outdoor ramps, and mechanics spent sweltering Texas afternoons rotating dust covers and space heaters to keep sealed bays within spec.

The Pentagon eventually restarted hand-overs under a deal that withholds the final $5 million per jet until TR-3 gains full combat clearance. Upgrades now flow into U.S. acceptance centers, but each tail number waits for a future software drop before it can employ AIM-260 missiles or high-power jammers. Hill crews call the interim jets “paperweights with wings,” a quip that surfaced during a February 2025 House Tactical Air hearing.

GAO’s April 2024 sustainment survey landed with fresh sticker shock: total life-cycle support is now estimated at $1.58 trillion, a 44 percent jump since 2018. The rise stems from longer planned service life, inflation, and slower than expected depot recovery rates. Flight-hour targets fell, yet readiness still trails goalposts; mission-capable figures hover between 51 and 56 percent depending on variant. Engine queues drive the bulk of downtime after a rash of stalled starts forced premature removals.

Pressure spilled into budget cycles. The FY-25 defense bill trims the annual buy by ten aircraft and directs the services to prove they can support what they own before placing larger orders. The same language blocks full-rate production until the Joint Program Office meets fifty open GAO recommendations, six of which date back to 2014.

Engine modernization remains unsettled. A 2023 statutory report pushed the Air Force to define thermal-management needs before signing contracts for either a core upgrade or a clean-slate adaptive engine. Lawmakers fear incremental fixes cannot handle future directed-energy weapons that Block 4 intends to host. The Joint Program Office acknowledges heat limits already throttle high-speed low-altitude sorties in the Gulf during summer months.

The logistics backbone also pivots. ODIN, the cloud-based successor to ALIS, entered limited service in October 2024 yet still runs side-by-side with its predecessor. Squadrons juggle two laptops per jet because data-migration scripts lag behind flying hours. Depot officers say a single bug in an ODIN patch forced them to hand-jam 1,900 part-condition reports last November. GAO plans a follow-on audit of ODIN cybersecurity by late 2025.

Lawmakers amplify scrutiny through open testimony. In March 2025 the House Readiness panel grilled sustainment chiefs on why depot cells still rely on borrowed milling machines from Palmdale while permanent tooling awaits budget release. Air boss Gen. Dale White conceded that capacity gaps slice engine turnaround time to 28 percent below plan.

The services answer frustration with revised tactics. The Air Force cut annual flight‐hour goals to ease engine wear; the Marine Corps shifted expeditionary concepts toward pre-positioned enablers rather than single-strip hops; the Navy delays full-rate decision gates until carrier test events finish with TR-3 hardware. Every move buys margin but chips at original promises.

Industry tries to dull criticism. Lockheed cites declining touch-labor hours per tail and boasts of a new digital thread that reduces kit-install errors by 65 percent. Pratt & Whitney promotes a core-upgrade path that slides straight into the current engine bay, avoiding airframe surgery. Yet GAO notes neither claim dents the uptrend in cost charts, and depot queues still stretch past 120 days for complex repairs.

Pilots at Nellis now fly a mixed fleet: Block 2B jets run older computers, early TR-3 tails carry partial software, and a handful of converted prototypes test Block 4 features such as AGM-88G anti-radiation missiles. Instructors keep three checklists on their kneeboards because cockpit symbology differs by tape. They call it “fifth-gen whack-a-mole” and shrug when maintainers ask which spare part applies to which serial. The sprawl underscores GAO’s recurring point that concurrency multiplies variants inside variants.

The throttle-valve hazard that headlined 2018 finally closed in mid-2021 after Honeywell introduced a redesigned sleeve. No further run-away events occurred, but the message stays relevant: each fix arrives on a jet that may already sit thousands of miles from overhaul benches.

Taken together, the 2025 picture looks much the same as 2018, only bigger and costlier. GAO still labels the project “high risk.” The Pentagon still calls the fighter essential for future wars. Counts rise, bugs surface, and auditors chase both through an expanding maze of part numbers. The next year will test whether TR-3 stabilizes Block 4 or triggers another halt. Either outcome will echo through budget hearings well into the decade.

REFERENCE SOURCES

1. https://www.gao.gov/assets/gao-18-360sp.pdf
2. https://www.gao.gov/products/gao-18-360sp
3. https://www.gao.gov/assets/d24106703.pdf
4. https://www.gao.gov/assets/gao-24-106703.pdf
5. https://www.gao.gov/assets/gao-23-106047.pdf
6. https://www.gao.gov/assets/gao-24-106909.pdf
7. https://breakingdefense.com/2024/08/pentagon-withholding-about-5-million-per-f-35-with-unfinished-tr-3-upgrade/
8. https://www.reuters.com/world/us/pentagon-withholds-5-mln-per-f-35-jet-deliveries-resume-2024-08-29/
9. https://www.congress.gov/event/116th-congress/house-event/LC65453/text

Click here for the Weapon Systems Annual Assessment report (206 PDF pages), both on the GAO website.