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

I have been perturbed for years that the AirNZ 777 Raro incident was never used to further the education/learnings of the Industry as a whole. If this does turn out to be a case of setting a low altitude in the MCP (or whatever it\x92s called on the 787) then the system that allowed that learning to be kept hidden definitely needs changing.

This got me thinking about a report I read where an Auckland based maintenance facility added too much biocide to an aircraft fuel tank by a factor of ten. From memory the Engineer simply read the instructions wrong or calculated the additive amount incorrectly and the cross checking systems were either not in place or they failed. I searched online for it but could only find the following;

So my point is, if we are speculating about fuel contamination causing dual engine failure, it is possible that a fuel contaminant is specific to a particular airframe and not the supply system. Obviously not saying that is what happened here, but it goes to show how many possibilities exist.

I\x92d like to give you another option to consider in what must be a worrying time;
Am I right in saying, from a mathmatical perspective, that dual engine flame out due biocide overdose would be more likely than a TCMA activation shutting down the engines? Considering we have examples of engines reducing to idle within seconds of each other in the past, but we have no examples of airborne TCMA issues I would have thought this to be the case. Likewise, nefarious intent also appears more likely statistically than a TCMA issue.
I have high-school level statistics under my belt so I pose that as a question for people much smarter than myself.

Nope.
Yes I remember the early days CRM courses where we watched it more than once. The Raro incident is comparatively recent and I chatted to enough ashen faced individuals in the halls to believe it to be a good learning opportunity for the industry.
​​​​​​​Edited to say Ollie posted at the same time.

​​​​​​​787 is not my type but that sounds about right to me. Sounds like OPT doing its job.

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.

Yes I agree that it’s unlikely that it was the same biocide as the Jetstar incident, or even a biocide at all. I just think that incident highlights the vulnerability of something ( fuel) that has direct access to both engines at the same time.
From what I can gather the biocides are required to be injected into the refuelling line with a special little wheel mounted pump in order to ensure it mixes evenly. Even something as simple as a U/S piece of kit and a late night work around could be problematic.
A day before the Jetstar engines rolled back we didn’t know that that particular brand was only 7% soluble in Jet A1, yet it was. Is it possible that another brand has another issue? Or that a fantastic brand of biocide is used excessively? Or that no biocide is used at all and the actual microbes clog the spool/ filter instead of other particulates? Or any other number of things. I know it’s unlikely, but something unlikely has definitely happened, I just wanted to point out that it may surprise us all as to how simple it is in retrospect.
As a side note, according to a quick internet search the biocide in question was rebranded with a slightly different name and is still available for purchase. ( not saying that it’s being used in Airliners, just that it’s still out there waiting to clog up your D8)

Yip I’m with you Gary. I don’t even think its likely that this is related to the crash, I might have written it poorly but I wanted to highlight that fuel is interacting with both engines, and we tinker with fuel…….. a lot.
One ENG Fail alert was at 1857hrs ( local) and the other ENG Fail alert was at 1858 hrs.

I agree with this. For all the SLF reading and not posting ( good work!) there is a delay between the end of the takeoff run and the gear being selected up. I fly 737’s so any 78 folk feel free to correct me but it looks like this;
PM: “ V1 ….Rotate”
The PF then begins to rotate the aircraft up to a pre determined attitude which is normally between 13 and 15 degrees. They do this at a rate of between 2 and 3 degrees per second so about 5 or 6 seconds later the aircraft is at its climb out attitude. The PM is then looking at their instruments to confirm that the aircraft has a positive rate of climb, this takes a moment, maybe 1 to 3 seconds then;
PM “ positive rate”
PF: “ gear up”.
So minimum 8 seconds but probably longer between the PM calling “rotate” and the gear being selected up.
The relevance of all that is to say that if you suspect that the gear up cycle has been interrupted by a dual engine failure, then the engines may well have been producing thrust up to an altitude of 50-100ft or so, which ties in nicely with the max height reached, distance travelled etc.
Mods this is clearly not a theory, just info for those who don’t fly airliners to aid understanding.

I imagine they would promulgate the information appropriately to ensure there is not a repeat performance.

User989 thanks for a nice summary
I am at risk of turning into one of those folks who gets their mind locked on one possibility and keeps banging on about it but here goes;
If the authorities determined that the accident aircraft had been treated by maintenance for microbial growth in the fuel tanks within the last week or so, and they suspected that that procedure was carried out in a way that could result in fuel contamination, then that would explain

1/ No other aircraft being affected
2/ No measures taken at the airport
3/ No AD’s from the regulators
4/ No grounding of 787’s
5/ Flight profile
6/ Rat deployment etc etc

I agree with your statement that dual flameout due fuel contamination is very unlikely, but we ARE dealing with something that is very unlikely. I favour the theory because an error in treating the fuel is so predictably human and simple, and a dual engine failure being related to fuel is also a simple and obvious idea, and it satisfies all we know both about the aircraft’s behaviour, and the authorities behaviour post accident.
I posted a report earlier of a 787-8 powered by the same engine type have both engines roll back sub-idle within a minute of each other while airborne due to this, so we know it can happen in theory.

Now……I want to be clear that I’m not saying I think I know what happened, I’m an average Joe with my hands full just flying the line, but I am a bit surprised that the idea of ‘fuel contamination specific to that airframe’ doesn’t get discussed more on this thread.
Thanks again for the clear summary of discussion thus far.