June 15, 2025, 15:31:00 GMT
permalink Post: 11902557
777/787 driver here.
When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again.
When you lift off the runway, the gear doors open REGARDLESS of gear lever position. If you do not raise the gear within 30 seconds, the gear doors close again and you keep the gear down as you apparently desire. In the video, the gear doors are closed again as the airplane flies into the suburb. This requires normal hydraulics in system C, which was apprently available as the doors are closed again.
1. 787-8 LG retraction: boogies tilt forward, doors open, boogies tilt inward:
Last edited by D Bru; 16th June 2025 at 04:24 . Reason: Following pertinent comments EXDAC & Roo (thanks!)
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Gear Lever
June 17, 2025, 22:37:00 GMT
permalink Post: 11904725
EEC MN4 - TMCA
Without a doubt one is looking at a very, very rare event, most likely the result of an unlikely/unlucky combination of issues, the grim gravity realised by the F/C (mayday) immediately after T/O. As a very, very FF/retired EU bureaucrat/economist/lawyer with an as ever staunch penchant for data/facts, I'm therefore wondering whether VT-ANB engines had already their EEC MN4 microprocessors replaced as mandated within 11000 cycles or 12 years per AD 2021-21-05
https://www.govinfo.gov/content/pkg/...2021-25491.pdf
. This AD was prompted by in-service occurrences of loss of GEnX engines thrust control resulting in uncommanded high thrust. Uncommanded high trust on (at least one of) the engines during the TO-roll, in particular past V1, resulting in a discrepancy with the actual (likely derated)thrust settings, could have triggered TMCA on or just before lift-off.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives GEnx (ALL) MAYDAY V1
June 17, 2025, 23:03:00 GMT
permalink Post: 11904743
BR, D Bru
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Preliminary Report Thread Moderation
June 26, 2025, 21:39:00 GMT
permalink Post: 11911519
https://www.pib.gov.in/PressReleseDe...x?PRID=2139785
Status Report on recovery and examination of data from Black Boxes \x96 Air India Flight AI-171
Note the front EAFR is the one with RIPS battery backup.
Status Report on recovery and examination of data from Black Boxes \x96 Air India Flight AI-171
Note the front EAFR is the one with RIPS battery backup.
1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss;
2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake.
Regards,
D Bru
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AI171 CVR EAFR RIPS
June 26, 2025, 22:05:00 GMT
permalink Post: 11911534
Really, Grumpy? If aft EAFR (not RIPS supported) would have had any data/voice after elec failure following T/O, I think the AAIB would have been more than happy to extract everything from that one since it was found earlier and most likely more intact than the front one. Regards
Last edited by D Bru; 26th June 2025 at 22:17 . Reason: Sorry but I didn't want to sound too "grumpy" ;)
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) EAFR RIPS
June 28, 2025, 17:04:00 GMT
permalink Post: 11912578
I am not certain on that. Remember the 737 didn't have them on the standby bus (Jeju). The NTSB doc states they're powered from the L/R 28VDC buses on the 787.
This shows the centre TRUs can only power the instrument buses not the L/R DC buses, the RAT can't really power the right TRU without powering both R1/R2 buses, and powering the left TRU would require powering the left 235/115 ATU which would probably be a lot of magnetising current even if not much actual load. The contactor naming supports that.
My money is on the L/R DC buses being unpowered in RAT operation; only the CA/FO instrument buses and the 235VAC backup bus.
This shows the centre TRUs can only power the instrument buses not the L/R DC buses, the RAT can't really power the right TRU without powering both R1/R2 buses, and powering the left TRU would require powering the left 235/115 ATU which would probably be a lot of magnetising current even if not much actual load. The contactor naming supports that.
My money is on the L/R DC buses being unpowered in RAT operation; only the CA/FO instrument buses and the 235VAC backup bus.
Last edited by D Bru; 28th June 2025 at 17:06 . Reason: deleting a repeat image of the elec system
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR Electrical Busses FDR NTSB Parameters RAT (All) RIPS TRU
June 28, 2025, 19:17:00 GMT
permalink Post: 11912637
The requirements I have seen indicate that RIPS is applicable only to CVR or the CVR function of an EAFD. If you are aware of any requirement for RIPS to support flight data recording would you please provide a reference.
FAA requirements and the discussion/changes that resulted from the initial NPRM here -
https://www.federalregister.gov/docu...er-regulations
FAA requirements and the discussion/changes that resulted from the initial NPRM here -
https://www.federalregister.gov/docu...er-regulations
Yes, possible electric failure on the eafr is of course a totally different story concerning voice recording
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): CVR FAA RIPS
July 01, 2025, 10:21:00 GMT
permalink Post: 11914168
05 THRE 180ft, TDZE 186ft
23 THRE 189ft, TDZE 189ft.
Google maps directions gives for walking from the nearest road next to the 05 THR (end of 23) to the accident site "mostly flat", i.e. going up 1m and going down 4m. That indeed can't add up to 50ft below RWY, more like 10/20ft, depending on the RWY elevation reference point. Moreover, the two floor building Air India 171 struck is about 20ft high.
Subjects: None
July 11, 2025, 23:43:00 GMT
permalink Post: 11920013
10 seconds
Baffled, as probably all of us. But 10 seconds between \x93cut-off\x94 and \x93run\x94 is not excessive imo:
08:08:42 - max speed
08:08:43 - cut-off eng 1
08:08:44 - cut-off eng 2; run-down eng 1
08:08:45 - run-down eng 2
08:08:46 - startle moment
08:08:47-48 - instruments, levers and switch scan
08:08:49-50 interrogate other pilot why he moved switches
08:08:51: other pilot denies
08:08:52: eng 1 fuel switch to \x93run\x94
08:08:53: it\x92s both fuel switches that were cut off
08:08:56: eng 2 fuel switch to \x93run\x94
08:08:42 - max speed
08:08:43 - cut-off eng 1
08:08:44 - cut-off eng 2; run-down eng 1
08:08:45 - run-down eng 2
08:08:46 - startle moment
08:08:47-48 - instruments, levers and switch scan
08:08:49-50 interrogate other pilot why he moved switches
08:08:51: other pilot denies
08:08:52: eng 1 fuel switch to \x93run\x94
08:08:53: it\x92s both fuel switches that were cut off
08:08:56: eng 2 fuel switch to \x93run\x94
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Switches Preliminary Report Timeline (Preliminary Report)
July 13, 2025, 21:49:00 GMT
permalink Post: 11921703
A few observations
While IMO the Air India 171 preliminary report (
PR
) in some aspects leaves ample room for speculation rather than soothing it, let’s not loose sight of a straight forward assumption that what is presently known to AAIB India beyond what is explicitly stated in the
PR
, at least to AAIB India’s judgement (and I presume amongst others NTSB's as well), shouldn’t lead to any significantly different preliminary observations and conclusions than those made in the
PR
at this stage.
In other words, there shouldn't be at present other major known/established facts based on the EAFR readouts (2000+ parameters!), but for now not published, that could immediately lead to other observations/qualifications than those made in the present PR .
If there would be, this would actually mean the end of authority of air safety incident investigation and reporting around the globe as we have known it for the past decades.
In other words, there shouldn't be at present other major known/established facts based on the EAFR readouts (2000+ parameters!), but for now not published, that could immediately lead to other observations/qualifications than those made in the present PR .
If there would be, this would actually mean the end of authority of air safety incident investigation and reporting around the globe as we have known it for the past decades.
Last edited by D Bru; 13th July 2025 at 23:16 . Reason: finetuning of argument :)
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AAIB (All) AAIB (India) EAFR Parameters Preliminary Report
July 14, 2025, 17:26:00 GMT
permalink Post: 11922380
Good analysis; AvH MN4 thing is an absolute ruse
The preliminary report narrows things down a lot but not as much as it could have done. The report will have been approved by several people. What we see is their consensus. Why did they choose this version?
The report is written to point the finger directly at: (i) the fuel cutoff switches and (ii) either pilot error or pilot mal-intent using them. The report is not written to point the finger at an electrical or mechanical malfunction.
...... The investigating team already knows. They could have disclosed more of the cockpit conversation, which would be a lot of help to us PPRuNers, but didn't need to. They have let Boeing and the type off the hook and put the blame on the pilots. They have fulfilled the primary purpose of an investigation -- to find out what happened.
Interestingly, they did not disclose whether it was error and mal-intent. Perhaps that is because they couldn't answer the grisly question: which is least worst, from the point-of-view of the airline, the victims' families and future customers?
Two posters above have quoted AvHerald's report that "... India's media reports that the investigation is NOT focusing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure." One interpretation of this is that the investigation knows all about the human action and that the system they refer to is the industry's approach to pilot mental heath and well-being.
YYZJim
The report is written to point the finger directly at: (i) the fuel cutoff switches and (ii) either pilot error or pilot mal-intent using them. The report is not written to point the finger at an electrical or mechanical malfunction.
...... The investigating team already knows. They could have disclosed more of the cockpit conversation, which would be a lot of help to us PPRuNers, but didn't need to. They have let Boeing and the type off the hook and put the blame on the pilots. They have fulfilled the primary purpose of an investigation -- to find out what happened.
Interestingly, they did not disclose whether it was error and mal-intent. Perhaps that is because they couldn't answer the grisly question: which is least worst, from the point-of-view of the airline, the victims' families and future customers?
Two posters above have quoted AvHerald's report that "... India's media reports that the investigation is NOT focusing on a human action causing the fuel switches to appear in the CUTOFF position, but on a system failure." One interpretation of this is that the investigation knows all about the human action and that the system they refer to is the industry's approach to pilot mental heath and well-being.
YYZJim
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AI171 Air Worthiness Directives Fuel (All) Fuel Cutoff Fuel Cutoff Switches Preliminary Report RUN/CUTOFF
July 14, 2025, 22:27:00 GMT
permalink Post: 11922550
Switching off the engines would cut power. (the RAT deployed before they overflew the end of the runway) The HUD would go blank. As would most of the display units. The lighting would change. The hissing of conditioned air would stop. Various 'noises' would cease. The engines sound would change dramatically, and they would feel the deceleration. The one EICAS screen remaining would be generating all sorts of messages. It would be obvious that power was lost.
I cant speak for how long it would take to connect the dots though.
I cant speak for how long it would take to connect the dots though.
https://data.ntsb.gov/Docket/Documen...man-Master.PDF )
Last edited by D Bru; 14th July 2025 at 22:39 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR EICAS Fuel (All) Fuel Cutoff Fuel Cutoff Switches RAT (All) RAT (Deployment)
July 15, 2025, 17:41:00 GMT
permalink Post: 11923115
Hamster wheel diversification (at least an attempt): 787 core system hacking
Inspired by the mention in the
PR
about a MEL on the \x91core network\x92, I came across the polemics between Boeing and IOActive a few years ago about the alleged vulnerability of 787 core systems to outside interference (hacker attack from within a/c and/or ground), including the highly sensitive CDN module, from where also the fuel cut-off module can be accessed. It\x92s definitely not my specialty, but I thought to flag it in case someone has more informed ideas about this. To my mind it could potentially \x93outshine\x94 intentional crew action. Boeing at the time denied such options, of course. Obviously also in good faith, moreover it seems to be Honeywell &GE code anyhow, but who knows where we are 6 years on.
https://www.wired.com/story/boeing-7...ecurity-flaws/
https://www.wired.com/story/boeing-7...ecurity-flaws/
Last edited by D Bru; 15th July 2025 at 18:10 .
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Fuel Cutoff Switches Honeywell MEL
July 15, 2025, 19:20:00 GMT
permalink Post: 11923194
A short response to you both:
1. Note that the article was from 2019
2. I am very doubtful that this occurred, beyond estimating the efficacy of any protections Boeing and Honeywell will have come up with since that article was published.
3. Caveat: yes, hackers never sleep .
But I think that you are both grasping at straws, for a variety of reasons…...
1. Note that the article was from 2019
2. I am very doubtful that this occurred, beyond estimating the efficacy of any protections Boeing and Honeywell will have come up with since that article was published.
3. Caveat: yes, hackers never sleep .
But I think that you are both grasping at straws, for a variety of reasons…...
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Honeywell