here’s an update to my initial comments (12.07.25) on the preliminary report published 11.07.25.
DISCLAIMER: This is a private analysis without any guarantee for the accuracy of the reported facts and conclusions.
in my opinion, the central and yet unanswered question is: did the fuel control switches physically move ?
The switches can be identified as HONEYWELL part number 4TL837-3D, a robust 4-PDT (Four Pole Double Throw) type switch with mechanical switch lock and LED illumination. It has been established by multiple sources competent with the matter that the 2 FADEC channels related to one engine are each “linked” to one switch circuit. The two remaining switch circuits seem to be connected to (independent) digital data hubs from which (among other devices) the 2 FDRs record their data. A single “double throw” circuit of the switch alternates a contact between 2 other contacts, switching a fixed DC voltage or resistance logic level between the two related logical positions “RUN” / “CUTOFF”. In a classical “analog” electronic sensing logic, any “noise” introduced to either of the contacts would likely be filtered or attenuated by the wiring or subsequent analog signal propagation. In a digital setup (B787 has a fully integrated digital data bus system), “noise” – depending on the way a logic level threshold is discriminated by logic level shifters, analog-digital converters (ADC) and software – could falsely be propagated as a “normalized” digital signal which is relied upon. If, for example, switch circuits are related to a common ground contact (as a reference towards a DC target switch level), it is thinkable that any voltage spike introduced into this common reference could shift digital switch state to a value not compatible with the physical switch position and this state being propagated as a binary state on 4 digital routes simultaneously, impacting both: fuel valves & DFDR recording. Since a DC ground reference is most likely shared among several devices in close physical vicinity, such ground voltage level “noise” could possibly affect both LH/RH control circuits. With further insight into wiring diagrams or the nature of the A/D interface, I admit that the nature of this analysis is highly speculative.
The instability of electrical power due to the dual shutdown (subsequently and partially recovered by RAT deployment, in the meantime hopefully bridged by main battery power) could have resulted in a restart condition of the aircraft’s digital data bus system, which could have cleared the digital CUTOFF states after system restart (corresponding to the 10-14s delay in the RUN transition) – without moving switch position.
There is an important third identification of switching (among switch lever position change and logic level change): switch “click” sound, which is strongly audible due to the robust physical nature of the switch mechanism (references 1, reference 2). The switch click(s) should be discernible on the FDR audio (in fact such audible features have been established as proof for operation of critical switches in numerous other crash investigation reports), not only in the CUTOFF transition (with maximum engine noise in the background) but specifically for the RUN transition that took place with engines below idle thrust and with low noise. Although the investigation specifically focused on fuel control switch operation, this feature has not been mentioned in the preliminary report.
From the above B787 cockpit videos, it is apparent that both switches can be operated within 1 second by an experienced cockpit crew member.
In summary: If it can be established by at least some of the possible 4 switch clicks in sync with recorded FDR data, that the switches have indeed physically moved, I would concur with the hypothesis of suicidal intent. If this cannot be established reliably, however, a “deep” electronics issue, possibly related to inertial force during rotation, such as described in my previous analysis, cannot be ruled out.