WASHINGTON — It was during a routine inspection in April that an Air Force technician found a single faulty Cartridge Actuated Device in the ejection seat of an F-35 at Hill Air Force Base, Utah. The device — known colloquially as CAD — contained no magnesium powder, a necessary material for generating the explosive charge that allows a pilot to begin ejecting from an aircraft.
At first, the potential issue was believed to be confined only to the F-35. By late July, however, the problem appeared more widespread, potentially impacting hundreds of aircraft across the US military’s tactical and training jet inventory that use ejection seats made by Martin-Baker, the UK-based firm that is one of two suppliers of ejection seats for the Defense Department.
Word — and worry — spread within the military, especially after the Navy’s public disclosure of the issue on July 26 seemed to trigger a series of cascading announcements about aircraft groundings. The Navy and Marine Corps acknowledged it was grounding a portion of its F/A-18s and training aircraft on July 27 to allow for ejection seat inspections, and the Air Force followed suit the next day, announcing the grounding of about 300 trainers. On July 29, Breaking Defense broke the news that the F-35 inventory was also affected by the issue, with a portion of the F-35 fleet grounded until the jets could be assessed.
In the midst of all that, Martin-Baker publicly acknowledged the initial problem actually occurred in April, provoking even more speculation. What was happening to the US military’s ejection seats, and why did it seemingly take the services so long to respond?
In interviews with Breaking Defense, officials from the F-35 Joint Program Office and the Air Force recalled a frenetic few months as the services grappled to understand the scope of the problem, develop a fix and communicate it to dozens of stakeholders at bases and maintenance depots across the globe.
Over the summer, the services and Martin-Baker examined more than 9,000 cartridges, both on the shelves of warehouses and inside the ejection seats of operational aircraft. Hundreds of aircraft — including a portion of the US military’s most advanced fighters — were forced to stop flying while the inspections occurred.
Altogether, the operational impact is difficult to gauge. While the Air Force has released data on how many F-35As, T-6s and T-38s were impacted by the potential problem, the Navy and Marine Corps have declined to detail how many of its fighters and trainers were forced to suspend flight operations, claiming operational sensitivities.
With F-35s, Super Hornets and EA-18G Growler electronic attack aircraft all impacted, the inspection process meant the US military had fewer aircraft available for pilot training and daily operations, potentially reducing the readiness of squadrons to respond to contingencies around the globe. And in the end, only four defective cartridges were found: the initial issue discovered in the F-35A in April, two cartridges of the same part number discovered by Martin-Baker in its stock, and another faulty CAD found by the Air Force in a supply warehouse, according to officials from Martin-Baker, the Air Force and the F-35 JPO.
But despite the loss of flight hours and the massive bureaucratic burden on the military’s maintenance and logistics corps for a handful of bad CAD, officials told Breaking Defense that the system worked as it should to ensure the services avoided a potential tragedy.
Launching a human out of the seat of a fast-moving, jet-powered aircraft is a complicated and dangerous process that requires various events to take place in sequence — and in some cases simultaneously — to ensure the pilot is not hurt as multiple explosive devices are detonated to propel the seat out of the plane. Whether a pilot’s ejection seat is properly working can mean the difference between life and death.
“[The problem] may not have been as bad as we thought,” said Col. Guy Spencer, the Air Force’s senior materiel leader for its munitions sustainment division. “But, when we’re talking about the safety of our airmen and air crew, it’s always important to err on the side of caution and preserve that safety margin as opposed to not.”
A Problem At Martin-Baker, ‘Medium Risk’ For The F-35
For an ejection seat to propel itself out of the cockpit and away from an aircraft, it must be equipped with the proper mix of cartridge actuated devices — cartridges filled with explosive material — and propellant actuated devices, which contain explosive gasses. Together, the two are known as CAD/PAD.
The CAD problem discovered this year stems back to October 2018, when the UK government mandated a change of the explosive handling process at Martin-Baker’s production facilities. Before that time, workers could leave incomplete cartridges in at the end of the work day and simply pick up their work the next morning, said Martin-Baker spokesman Steve Roberts.
However, under the new requirement, the United Kingdom declared that all incomplete cartridges must be labeled, packaged and removed from the work center and placed into overnight storage, Roberts said. (The Air Force’s Spencer said those changes were not properly communicated to the US government.)
Martin-Baker believes the quality lapse occurred after workers received units back from overnight storage, Roberts said. Although some cartridges had not fully moved through the build and inspection process, the production cards were marked as “complete.”
As the cartridges moved down the production line, the standard quality assurance processes failed to identify these cartridges as defective. “The following processes of leak test and X-ray would not detect the lack of powder fill,” and “the cartridges selected at random for lot acceptance firings did not include” the impacted cartridges, Roberts said.
At some point in time, a defective cartridge made its way into the ejection seat of one of the F-35As at Hill Air Force Base, and there it stayed until it was noticed by a maintainer in April.
After that discovery, the first step the F-35 Joint Program Office took was to assess the safety risk to pilots, said Air Force Lt. Col. Jessica Wright, the JPO’s aircraft and pilot system lead.
All three variants of the F-35 carry the Martin-Baker US16E ejection seat, each with 12 different types of CAD that play different roles in the ejection process. The faulty cartridge that was found at Hill AFB is one of the two “seat initiator cartridges,” which are located on the left and right sides of the seat and play a critical role in boosting the seat out of the cockpit.
Even if one seat initiator cartridge fails, the other still contains enough explosive powder to launch the pilot out of an aircraft, Wright said. However, if the CAD problem was pervasive enough that both cartridges were likely to be defective, it could have resulted in a failed ejection and death of the pilot.
“The safety of our air crew is always our number one priority. And so that was one of the things that we looked at immediately,” she said. “We had a team of professionals that were doing that safety system risk analysis, to determine what the odds of” a failed ejection were.
Within a matter of days of discovery, the JPO had finalized the risk assessment, which placed the safety issue in the “medium risk” category, given the statistically low probability of an ejection, coupled with the low probability of having both initiator cartridges fail, Wright said.
While the JPO conducted its risk assessment, Martin-Baker did its own investigation to determine the scope of the quality lapse. The company ultimately found that 9,000 CAD units were at risk of being defective, a fraction of the about 450,000 cartridges produced between October 2018 and April 2022, Roberts said.
After the Navy disclosed the CAD issue in late July, the announcement seemed to be followed by a string of groundings among the Navy and Marine Corps, the Air Force and finally within the F-35 enterprise. That created a lingering question: Why did the services wait until this summer to ground F-35s if they were aware of the problem all the way back in April? The answer, JPO officials told Breaking Defense, is not very straightforward.
Once the JPO understood that safety risk to pilots was relatively low, it began developing an inspection procedure to ensure that the initiator CADs would function as specified. “That took a little time,” Wright said, owing to the complexity involved in validating that test processes worked and could be repeated by maintainers without being overly onerous.
In July — three months after the discovery of the defective CAD — the program office released a Time Compliance Technical Directive, which gave the services 90 days to conduct inspections and laid out specific actions the services should take to validate whether initiator CADs were filled with explosive powder.
Although the directive allowed the services to continue flight operations as normal and conduct inspections as part of regular maintenance, the services opted to halt flight operations for the portion of their F-35 fleet suspected of carrying the defective CAD, returning individual aircraft back to flight status once its cartridges had been checked.
Operators’ concerns about the safety of their ejection seats may have also contributed to the Navy, Marine Corps and Air Force grounding aircraft, even though, Roberts said, “outside the F-35 program, Martin-Baker continued to recommend no action for all world-wide operators.” Additional inspection activities carried out on Air Force, Marine or Navy aircraft were carried out “for the sole purpose of maintaining aircrew confidence with the use of their ejection seats.”
Wright acknowledged that “there was a sense of anxiety, in that there should always be a sense of anxiety when we’re dealing with the pilot’s last moment to make a decision to eject the aircraft. It has to work; it has to be no-fail,” she said.
However, in hindsight, Wright said the program office should have done more to educate pilots and maintainers about the actual risks — or lack thereof — and address safety concerns “so that folks didn’t have to jump to their own conclusions with impartial sets of data.”
The Rattle Test
For the F-35s, inspections involved extracting both the left and right seat initiator cartridges, which required either a full or partial removal of the ejection seat, Wright said. (She declined to detail the process of a partial seat removal for classification reasons.) The removed cartridges were allowed to come up to room temperature, after which a maintainer could perform a “rattle test” — basically shaking the cartridge and listening for the presence or absence of powder.
If the rattle test was inconclusive, the cartridge would be X-rayed and then assessed by a technician, Wright said, adding that maintainers were liberal in pushing CAD to be X-rayed to ensure “to the utmost degree of safety and assurance that that powder is in there.”
The JPO was involved in the inspection process “in varying degrees,” helping to coordinate between the services when Explosive Ordnance Disposal teams or other specialized experts were needed.
For instance, at Luke Air Force Base in Arizona, “we had the Air Force maintainers and ammo experts pulling the cartridges from the aircraft,” Wright said. “And then as the [Marine Corps] EOD team was X-raying them, we had a Navy civilian who was a level three X-ray technologist that was reading the result of X-rays and able to clear the CADs as good and safe to fly.”
“It was almost like a merry-go-round of those three processes happening,” Wright said. “And so for the aircraft that were at Luke Air Force Base, they had completed those inspections in about three days.”
The Navy completed its F-35C inspections on July 26, Cmdr. Zachary Harrell, spokesperson for the Commander of Naval Air Forces, announced in a July 29 statement. That same day, the Marine Corps noted that 90 percent of its own fleet of F-35B and C models had gone through inspections. All Marine Corps’ F-35s have since been cleared to fly.
The Air Force’s F-35s returned to flight on Aug. 15, after technicians inspected a total of 706 cartridges from 349 F-35A conventional takeoff and landing models. Although the service identified four “suspect” cartridges, which were removed from ejection seats and replaced, those devices were later found to be compliant, according to an Air Combat Command spokeswoman.
Meanwhile, At The Navy And Marine Corps
When the defective CAD was found on the F-35 in April, defense officials asked if other aircraft types could potentially be impacted. Initially, the response from Martin-Baker was that there was no risk of impact to the rest of the military aviation fleet. But as the investigation continued, it became clear that the quality defect could potentially affect cartridges used by other Air Force, Navy and Marine Corps aircraft, the Air Force’s Spencer said.
“They had to go back and do a lot of record screening on site at Martin-Baker to go through the various product lines, and we’re talking thousands and thousands of records, to understand the potential impacts,” he said. “And so that just took time for them to work through, to provide good data to the government for us to be informed and make decisions on where to go with this.”
Naval Air Systems Command (NAVAIR) had been the first entity from the US military to acknowledge the CAD problem publicly, announcing on July 26 that a “limited number” of cartridges from the F/A-18B/C/D Hornet, F/A-18E/F Super Hornet, E/A-18G Growler, T-45 Goshawk and F-5 Tiger II training aircraft could be affected by a defect.
On July 27, a NAVAIR spokeswoman confirmed to Breaking Defense that an undisclosed number of aircraft had been grounded to allow inspections to take place, with aircraft returning to flight after a technician had confirmed that the cartridges were properly manufactured.
“While the Hazard Risk Index placed the probability of a mishap occurring at ‘very low,’ out of an abundance of caution, Navy leadership took rapid action and made the decision to issue an aircraft grounding bulletin for aircraft that contained CADs produced in specific production lots,” NAVAIR spokeswoman Marcia Hart said in a Sept. 13 statement.
The Navy and Marine Corps have inspected all cartridges suspected to be defective, and all aircraft have returned to flight status, Hart said. However, NAVAIR declined to detail how many aircraft were grounded or when inspections had been completed, a contrast to the information provided by the Air Force.
When asked how many defective CAD had been found on aircraft and within Navy and Marine Corps stock, NAVAIR also declined to comment, stating “due to operational security concerns, we will not discuss exact numbers.” However, a Navy news release specified that Navy technicians screened more than 4,400 cartridges with no defects found.
Although the Navy has provided few details on the operational impact of the issue on a wide array of its tactical aircraft, the service’s Naval Surface Warfare Center Indian Head Division (NSWC IHD) seems to have been pivotal in assisting the other services carry out fleet inspections.
For instance, the NSWC IHD worked with the F-35 Joint Program Office to develop methods of testing the cartridges to verify whether they contained magnesium and other energetic materials, including using a “portable radiographic inspection procedure,” that was used for on-site inspections of F-35s, the Navy stated in a news release. The organization also assisted the Air Force with scanning and evaluating CAD, Air Force officials said.
Naval technicians also worked 12-hour shifts throughout August — often in warehouses with temperatures exceeding 100 degrees — to screen, validate, repackage and ship CAD components, the news release stated.
For Air Force Trainers, Inspections Continue
On July 28, the Air Force grounded almost 300 T-38 and T-6 trainers so that maintainers could inspect those aircraft’s ejection seats for faulty CAD. It’s been two months since that directive has been issued, and the Air Force remains the only service with planes still grounded and moving through inspections.
It’s also been the only service that has found a defective cartridge during the inspection process, which was discovered in the Air Force’s stockpile of spare CAD/PAD, Air Force officials told Breaking Defense.
Like the other services, the Air Force took a two-pronged approach to scour its training enterprise for faulty CAD: evaluating the loose cartridges in its supply warehouses and depots, as well as inspecting all T-6s and T-38s that could potentially be outfitted with the faulty CAD.
Both the T-6 and T-38 use different variants of the Martin-Baker Mk16 ejection seats — a precursor of the F-35’s US16E. The T-6 and T-38 ejection seats sometimes use different CAD/PAD, as differences between the two aircraft lead to variations in the ejection sequence.
Unlike the F-35 inspections, which involved evaluating two cartridges of the same type per ejection seat, the Air Force assessed that there were six unique cartridges on the T-6 and T-38 that potentially could be missing the ignition powder, Spencer said.
The Air Force identified 88 T-6 and 239 T-38 trainers as potentially having defective CAD devices, said Abbigail Pogorzelski, chief of the Air Force’s legacy training aircraft division. Because the ejection seat needs to be removed in order to pull out the suspect CAD and examine them, it takes about eight hours to complete an inspection.
As of September, no faulty cartridges have been found on any of the aircraft inspected thus far, with only 72 T-38s left to be inspected and all T-6s having moved through the process, she said.
However, the Air Force has discovered one cartridge “that has been verified to have been missing the ignition powder” while doing screenings of loose CAD at its supply warehouses, Pogorzelski said.
So far, the Air Force has screened about 1,690 of the 2,800 suspect cartridges in the T-6 and T-38 supply chain, Pogorzelski said. To do those screenings, the Air Force sends those potentially defective cartridges from its warehouses to Hill Air Force Base in Utah, where they are scanned by an X-ray to ensure that they contain ignition powder.
“We’ve developed, in conjunction with the Navy, techniques using 2-D digital X-ray and CT scanning, to take images of each cartridge,” Spencer said. “It took a while to make sure we got the right angle and setup for each one of them to make sure that there’s sufficient contrast in those images to identify the ignition powder.”
For all the critical elements of an ejection — the explosives that begin the ejection sequence or boost the seat from the aircraft— the T-6 and T-38 have redundant systems in place, making a failed ejection “improbable,” even if the pilot ejected in a seat with faulty CAD, Pogorzelski said.
But although the risk to T-6 and T-38 pilots turned out to be “negligible,” Spencer said that the Air Force was correct in taking a conservative approach and halting flight operations based on the initial data it was given on the scope of the quality escape.
“It really comes down to, you know, is it one failure? Multiple failures?” Spencer said. “There’s a lot of ‘what if?’ scenarios that you’d have to go through to characterize the probability of a non-successful event occurring.”
Back In The Air, Cautiously
More than two months after news of the ejection seat issue broke, just about all the potentially affected planes are back in the air, but not before the military embarked on a complex campaign to investigate the problem and Martin-Baker updated its manufacturing process to reduce the chances of another quality lapse.
“The change in serialization from the end to the start of the build process allows more detailed operation-by-operation record keeping that will prevent human error from circumventing the inspection process,” said Roberts, the Martin-Baker spokesman. “X-ray techniques have been changed to ensure that records will exist for the presence of powder.”
With so few issues actually found, there’s a question about whether the military’s response was overly dramatic. After all, one could argue, these are single pieces of redundant systems.
However, recent history shows that, when an ejection seat is made with defective components, the consequences can be catastrophic.
An internal Air Force investigation into the June 2020 death of First Lt. David Schmitz, an F-16 pilot from Shaw Air Force Base, South Carolina, found that counterfeit materials may have caused his parachute to fail to deploy during an ejection, Air Force Times reported earlier this month. Schmitz’s widow is now suing three defense companies for negligence after several ejection sequencer components — such as transistors and microchips — came under suspicion of being fake.
Schmitz’s death is unrelated to the CAD issue, which was specific to Martin-Baker ejection seats. The F-16’s ACES II ejection seat is built by Collins Aerospace.
For the ejection seat inspections this summer, service officials reiterated that pulling aircraft off of flight status to do ejection seat inspections is a small price to pay in order to keep pilots safe, should an emergency strike during operations.
“On that pilot’s worst day, I’ve got to be able to say that the team did everything they humanly could to ensure he or she had safety of flight and the ability to eject when they needed to,” said Wright. “If there was the potential for an issue with one of the cartridges, the inspection was working the way it was supposed to.”