Posts by user "Gary Brown" [Posts: 11 Total up-votes: 0 Pages: 1]

"The probability of a technical cause is high."

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.

In that report, the factual conclusion is:

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.

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"....

The forward installed EAFR along with the Cockpit Area Microphone and Preamplifier are typically connected to the Recorder Independent Power Supply (RIPS), providing a backup power source for 10 minutes in the event of power interruptions.

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.

The extended spec sheet for these switches shows that there are versions with a center indent, and others without. But the picture up above which is said to be of the 787/8 actual switch seems - to me - to not have a center indent option. Ie, it is either on or off, with a spring loaded lift of about 2mm needed to move it from one position to another.

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.

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?

In the Gatwick take-off incident discussed above, 38 x the correct dosage of biocide was mixed in with the fuel. In the Japan descent case also discussed above it was probably 10 x the correct dose....[NB, I originally, and very incorrectly, said 100 x the dose, having mis-read the relevant paragraph). In the Gatwick case, the ground guys doing the dosage had never done it before, and were working from the manual. They did not understand what ppm (parts per million) meant and had to google it. They then miscalculated the dilution necessary.

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).

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.....

You're right that I am wrong about the 100 x figure ..... The Japan report doesn't fully resolve the concentrations issue (see below), but at p. 10 of the report they summarise similar incidents where they believe 10 x the recommended dose (1000ppm instead of 100ppm) was used. I'll correct the original post. But, we have incidents where the over-dosage is between 10 and 38 x that recommended....

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.

BTW, pondering some of the perhaps slightly ambiguous phrasing in the Preliminary Report, I asked a Hindi-speaking friend to look at the Hindi language version. But it turns out - very much open to correction! - that the Indian AAIB issues its reports only in English (Hindi and English are the two official Indian Govt languages). A clue is that Indian AAIB reports don't have that note you often seen in, eg, French English-language Accident Reports that, in the event of differences, the French language report rules. So, what the AAIB said is what it meant to say.