Page Links: Index Page
Gary Brown
2025-06-17T09:35:00 permalink Post: 11904142 |
"On Jun 17th 2025 an official, a former Air India Captain trained by the Captain of the accident flight, stated, that the CVR has been successfully read out, the voices on the CVR are very clear. It is becoming gradually clear from the newly emerging evidence that there was probably zero negligence in the cockpit, the crew did not give up until the very last moment. The probability of a technical cause is high. A preliminary report by India's AAIB can be expected in a few days."
AvH If this report is accurate, I'd hazard that a specific maintenance issue has been identified. If the "technical cause" was a system or parts failure or fault, then I'd expect a lot of similar 787s to have been grounded by now. Last edited by Gary Brown; 17th Jun 2025 at 10:04 . Reason: Clarity Subjects: AAIB (All) CVR Preliminary Report 3 users liked this post. |
Gary Brown
2025-06-17T11:43:00 permalink Post: 11904233 |
There is a possibility that doesn\x92t get much air time on this forum that satisfies all the \x91facts\x92 ( pprune facts mind you), and requires less mental gymnastics to believe than many of the theories put forward. I\x92m not saying it\x92s what happened at all but it seems much more likely than a TCMA fault to me.
This link is to a Japanese report on a Jetstar 787-8 with GE engines that had both engines drop below idle while airborne due to magnesium salts effecting the operation of the FSV spools. The Magnesium salts came from a biocide dose by maintenance two days earlier. For some reason I can\x92t paste the link but if you google JTSB the report number is AI2020-2. I think it\x92s quite easy to imagine that a simple maintenance error ( 1000ppm instead of 100ppm) combined with extremely bad luck on timing lead to this accident. I think I\x92m favouring a theory like this for its simplicity and the fact that fuel is the elephant in the room when you are dealing with a dual engine failure. 4. PROBABLE CAUSES In this serious incident, it is highly probable that, when the Aircraft was descending for landing, there occurred oscillation in rpm of each engine causing both engines to temporarily fall below idle at separate times because Residue primarily composed of magnesium salts accumulated in spools impeded movement of spools that involved in fuel metering of both engines. (emphasis added) and the narrative taken from the pilots is that while they happened in short order, the engine issues were not simultaneous. Not to say they couldn't be simultaneous, but they weren't. Also, the problems arose in the descent, as the engines were throttled back. Again, not to say it couldn't happen in the take-off, under full power. Subjects: Biocide Dual Engine Failure Engine Failure (All) Maintenance Error TCMA (All) 3 users liked this post. |
Gary Brown
2025-06-18T07:18:00 permalink Post: 11904984 |
Up above - apologies I can't find the post... - someone mentioned that the EAFRs
might
send data wirelessly..... Here's the GE "brochure" for the current EAFR (although I am not certain exactly which model would be on the subject aircraft):
https://www.geaerospace.com/sites/de...rder-3254F.pdf which is an interesting read on what EAFR can and can't (or at least, doesn't) do. It's clear - to me - from that document that wireless data transmission is not a feature of the EAFR. Basically, ethernet cable only. Some data acessible on the aircraft itself, some (CVR in particular) only available when the EAFR is in the lab. One thing I did not know is: The Image Recorder growth function is used to record visual images of the flight deck instruments, flight deck, the aircraft structures, and engines as required. The final two words of course mean that Air India 787s might, or might not, have that feature enabled. And indeed, it being called a "growth function" probably means "not currently implemented".... Last edited by Gary Brown; 18th Jun 2025 at 07:53 . Reason: Query on "growth function" meaning. 1 user liked this post. |
Gary Brown
2025-06-19T09:20:00 permalink Post: 11905856 |
https://www.geaerospace.com/sites/de...rder-3254F.pdf The rear EAFR doesn't have power backup. So it will only record data (both CVR and FDR) while it has normal electrical power. At what point before impact that power was lost, we do not know. 2 users liked this post. |
Gary Brown
2025-06-19T12:49:00 permalink Post: 11905995 |
The spec sheet says 100,000 cycles.
Switches fail sometimes. I have changed lots of lots of malfunctioning toggle switches in my day. But both at the same time? It has to be a common thing happening at the same time. Someone slipping both switches into a worn middle detent is such a thing though, that is one habit that could be developed. A slight bump at takeoff and they both go to cutoff. [emphasis added] Or they are worn and theres an iphone behind the throttles, as someone mentioned. The switches themselves are on-on 4 pole toggles, and doesn\x92t fail into one position over the other, and gravity would prefer the cutoff position in this design. I mentioned I have used my share of switches, knobs and buttons. In much larger quantities than what you find in aircraft, but without the life and death factor, and thus no SOP. Unexpected things happen, no one dies, but I myself brodcasted jolly sounding very inappropriate intro music over a very dark news report on the unravelling Joseph Frietzl case by dropping my phone on a switch. Several million viewers, a good chunk of which called to complain. Grave errors can be banal. Other than that, common connectors, the harness itself, I have seen a large amount of unexpected electronic things happen when those get bendt the wrong way. Subjects: None |
Gary Brown
2025-06-20T14:12:00 permalink Post: 11907006 |
If I may - going back to the upthread report of an Indian Express newspaper interview with "an official" who was pointing at possible "water contamination". This is very misleading by either the "official" or the newspaper. The incident specified by "the official" near Gatwick in 2020 is this one:
https://www.gov.uk/aaib-reports/airc...-february-2020 which was explicitly biocide contamination not water. As in the Japanese similar case discussed here already, the excessive biocide use caused chemical reactions in the fuel that - eventually - caused starvation and abrupt shutdown. The Japanese incident , discussed already above, has much more detail on how the biocide is used and what happens if it's used excessively. I do not know how Air India / Boeing / Ahmedabad do their biocide treatment, but it appears generally (from a good number of accident / incident reports) that it is very particular to the given aircraft. Once the desired fuel load level is known, a desired concentration of biocide can be calculated for that fuel load. That biocide is then introduced, via an intermediate little bowser, into the specified quantity of fuel being loaded on the tarmac into the subject aircraft tanks. So, the biocide does its thing in suspension in the regular fuel, as the aircraft operates its route. In a number of cases, orders of magniture more biocide (of which there are various brands) has ended up in the fuel, causing engine shutdowns at very difficult moments. So, some questions. If the investigators are looking at a biocide contamination: - after such a fireball, would there be any way of determining whether the fuel had in fact been biocide contaminated? Perhaps the inner surfaces of the tanks? Assorted valves and piping along the fuel route? - what relevant engine parameters are captured and (hopefully) usefully recorded by the FDRs? A couple of incident reports have mentioned monitoring of the exhaust gases, with an ability to detect contaminants as they are expelled. - does anyone here know what records are kept regarding the biocide treatment at the point of fuelling? Iirc, in the Japanese incident it was forensic interviews with the ground crew responsible that revealed the details of the error, rather than captured hard data. Last edited by Gary Brown; 20th Jun 2025 at 14:23 . Reason: Typos Subjects: Biocide Parameters 1 user liked this post. |
Gary Brown
2025-06-21T12:27:00 permalink Post: 11907703 |
This has been very briefly mentioned - inside a "quote" from an "official" - uptread, but I don't think has been specifically discussed here.
It "seems" that the Gujerati Anti-Terrorism Squad (ATS) have recovered a DVR (digital video recorder) from the accident aircraft: https://www.financialexpress.com/ind...dence/3879001/ As I understand it, the ATS were there to assist as necessary, not because of any posited terrorism link. The article posits that: The DVR in aviation settings records footage from CCTV cameras installed throughout the aircraft, including the cockpit, passenger cabin and entry/exit points. This footage is crucial for investigators as it provides visual evidence of activities before and during the flight, such as passenger boarding and ground operations. I'd not hear that Air India had such devices installed (the EAFR combo black box on the accident aircraft does have a "growth function" for adding video recordings at some future date). What's more the DVR seen carried by a "ATS Agent" in the picture and linked videos looks to me first undamaged and second like a domestic DVD player..... Anyway, anyone know more of a DVR fitted to Air India aircraft for investigative purposes? 1 user liked this post. |
Gary Brown
2025-06-21T16:31:00 permalink Post: 11907891 |
Some assumed numbers about normal biotreatment.
https://www.biobor.com/wp-content/up...ation-IATA.pdf If we assume 50 tonnes fuel load a 100ppmw biotreatment will be 5kg of biocide total in all tanks. The GEnx-1B will burn about 4,5kg/s fuel each on a take off run (give or take a bit) so 9kg/s in both donks for about 20s until rotate. So the total nominal biocide dose could be pumped in about half a second through both engines on take off power if it where not mixed at all and arrives in both engines at the same time. This gives you an idea that with the nominal amount of biocide dose not much could have happened. If biocide is the source of this dual EFATO than an extreme overdose in addition to wrong application preventing mixture with the fuel had to be the case. Neither incident reports make for pretty reading. But, in neither case did they experience near-simultaneous engine failure (not far off that, but still assymetric). Last edited by Gary Brown; 22nd Jun 2025 at 08:19 . Reason: Correcting math error from 100 x to 10 x ... Subjects: Biocide EFATO Engine Failure (All) 3 users liked this post. |
Gary Brown
2025-06-21T17:36:00 permalink Post: 11907923 |
I'll double check my claim of 100 x for the Japan incident tomorrow. I'm on cooking duty this evening..... Subjects: AAIB (All) 1 user liked this post. |
Gary Brown
2025-06-22T08:15:00 permalink Post: 11908347 |
For the Gatwick indident, read p2 of the AAIB Final Report for the figure of 38 x correct dosage. The rest of the report will tell you how AAIB arrived at that figure (mostly, though not entirely, by testing the fuel post landing...).
I'll double check my claim of 100 x for the Japan incident tomorrow. I'm on cooking duty this evening..... The difficulty in ascertaining the over-dosage in all these instances is that a) there was no general requirement to keep a record of the concentration calculated and used, and b) in each case the biocide admixture was done several days, several flight cycles, and several re-fuellings before the incident, and in most cases at a maintenance facility a long way from the incident route. Subjects: AAIB (All) Biocide 2 users liked this post. |
Page Links: Index Page