Lots of interesting technical aspects to this. None of them good.
The AFRL report acknowledges "AFRL has not seen evidence that any of the suspect counterfeit components were causal in the failure of the ACES-II ejection system." and "Presence of counterfeit parts in DRS would not necessarily result in operational failure of ACES-II ejection system."
So, based on what they know now, they haven't been able to tie potential counterfeit parts to the ejection seat failure. They haven't been able to rule them out, either. They also twice mention finding "obsolete" parts in the DRS. I wish they'd go into that more - how'd they know they were obsolete? Older part number, or date code, or similar?
On another note, they also raise concerning questions about what Teledyne (the manufacture of the DRS) did with it after the mishap. Seems like they were doing all kinds of testing and analysis, with no regard for maintaining the DRS as a piece of evidence in the mishap. Handing the unit off to the manufacturer like that, with no controls in place, seems like a real gap.
The AFRL report also brings up "Counterfeit components in DoD inventory has been an ongoing problem over the past few decades. Often the manufacturer/supplier is not aware the components are counterfeit. The DoD is aware of this problem and is working to eliminate these components from supply chains."
Supposedly, there are checks and balances in place to guard against counterfeit parts. In theory, you should be able grab an avionics box, and trace the pedigree of every subcomponent back to where it was manufactured. I think in reality, that's not always the case. And when you get down to commodity-level components like flash chips and the like, it's very much a "race to the bottom." Corners inevitably get cut, and someone pads their profit margin (wittingly or unwittingly) by introducing counterfeit parts.
Hadn't read the AIB before this, but the section on Substantially Contributing Factors has a section on "Ejection Seat Malfunction" on page 45-46 of the .pdf. Issues with the DRS were highlighted during an ejection in 2014:
Following the 2014 DRS failure, a time compliance technical order (TCTO) 11P2-3-502, Installation of the Shorting Plug on the DRS Electronic Module, was issued on 20 January 2016. The shorting plug was designed to prevent noise bias issues observed in channel three of a three-channel system. Two channels are required to be in agreement for the DRS to function properly. Channel three noise bias issues have been observed in approximately 9% of all live ejections and sled tests. TCTO instructions allowed for installation of the shorting plug during regularly scheduled 36-month maintenance/inspections.
This presence of noise on one of the channels makes this sound like a crappy design to begin with. Shit happens in electronics design, but would have hoped that aircrew escape systems would be designed to a higher standard. And adding a "shorting plug" sounds like a technical band-aid. Would like to see the TCTO itself, along with the other technical data contained in the AIB tabs, but it appears those aren't publicly available.
Regardless, they issued the TCTO in 2016. The mishap airplane was on the schedule to get the mod during scheduled maintenance in 2017, but the parts were "not available." Things like a "shorting plug" are not complex, so it's kind of unconscionable that they weren't available. Regardless, because of the parts unavailability, they pushed the TCTO to the next 36 month maintenance scheduled for July/August 2020.
In the meantime, much like many ejection seat components, the DRS has a limited service life (in this case, 10 years). This expired in Feb 2019, but received three life extensions from the Air Force Life Cycle Management Center out to July 2020. So, I assume three individual 6 month extensions. Would like to see the technical backing for justifying those extensions. Someone within AFLCMC should be able to produce some no-shit life cycle analysis that substantiates the life extension. And maybe they can, but my limited experience has been that someone may have just signed off the extensions with a cursory glance of past data.
In the meantime of all of this, a replacement for the DRS was fielded that negated the need for the TCTO. This was the Modernized ACES II Seat Sequencer (MASS), and became available in May 2020. The AIB isn't clear what happened here, but it sounds like the installation of the MASS was scheduled for the next time the seat was due for it's 36 month maintenance in July/August 2020.
I don't know how it works turning wrenches on ejection seats. In a perfect world with unlimited resources, every ejection seat mod would be given the highest priority, considering the implications. But it seems like that's not the reality, and mods were scheduled with convenience and efficiency in mind, not aircrew safety.
Sadly, the incident happened 30 June 2020, just short of the planned ejection seat maintenance.
TL;DR:
Problem with the DRS was found in 2014. TCTO issued in 2016 with what amounted to a simple, "band-aid" fix of a shorting plug. Mishap seat was pulled for scheduled maintenance in 2016, but TCTO parts not available. So, TCTO was pushed 36 months, to the next scheduled seat maintenance period in July/August 2020
In the meantime, the DRS should have been removed anyway due to reaching it's life limit. The Air Force issued three 6-month extensions, in order to line up with the next scheduled seat maintenance.
There was a new and improved replacement for the DRS that was fielded, the MASS, but rather than replace immediately in May 2020, that was also lined up for that July/Aug 2020 date.
Aircraft crashed just a couple months short of that next seat maintenance, and seat failed due to a faulty DRS. The DRS was past it's service life, had a known defect, and had a bunch of (potentially) counterfeit parts.