The crash landing of an F-35B near Lockheed Martin’sLMT -0.1% assembly line in Fort Worth, Texas two weeks ago, has not only grounded a number of F-35s until at least early January - it has halted deliveries of the stealth fighter to the U.S. and its allies.

Just before the New Year’s weekend, Lockheed Martin announced on Friday it has halted acceptance flights and deliveries of new F-35s as an investigation into the cause of the F-35B mishap unfolds. The cessation of deliveries means that Lockheed will not meet its contractual obligation to hand over 148 F-35s to the Pentagon in 2022.

Defense News obtained a statement from Lockheed spokesperson, Laura Siebert, who acknowledged that “given the delivery pause, we delivered 141 aircraft” this year. The delayed delivery of seven F-35s until the mishap investigation clears a resumption of acceptance flights for the military may seem trivial but as I’ve previously observed, Lockheed Martin’s production schedule is under pressure with a raft of European orders, the latest from Germany.

The acceptance flights, generally performed by military pilots acting on behalf of the Pentagon’s Defense Contract Management Agency, confirm the functionality of each new-build aircraft before the Services sign-off on delivery. While the exact nature of the F-35B accident that led to the stoppage of functional check flights is unknown, possible changes to the aircraft’s propulsion system - reportedly related to a tube used to transfer high pressure fuel to the airplane’s Pratt & Whitney F135 engine - in the latest production lot may signal a problem Lockheed needs to understand before deliveries resume.

The delivery pause is the latest black eye for an aircraft 20 years into development and first declared operational in 2015 by the Marine Corps. The F-35 Joint Program Office, which grounded an unspecified number of F-35s earlier this week with a Time Compliance Technical Directive [TCTD] maintained that they will be barred from flight pending the investigation and until procedures can be developed for their return to flight.