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D Bru
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. Last edited by D Bru; 28th June 2025 at 17:06 . Reason: deleting a repeat image of the elec system |
DaveReidUK
June 28, 2025, 19:10:00 GMT permalink Post: 11912632 |
However you are correct in that the requirements only specify that the CVR functions and the CAM must continue to operate. |
PJ2
June 28, 2025, 19:12:00 GMT permalink Post: 11912634 |
That's exactly why I would really recommend reading through the NTSB FDR report on the 2013 JA829J Boston incident helpfully posted by
EDLB
. There's potentially a wealth of data concerning a to me at least surprisingly number of 2000 of parameters written on a 787 EAFR, that is that at least if there's elec power. Even the 10 min RIPS is useless if there's no data sent from electrically shut off systems.
Auxiliary Power Unit Battery Fire Japan Airlines Boeing 787-8, JA829J Boston, Massachusetts January 7, 2013 |
EXDAC
June 28, 2025, 19:40:00 GMT permalink Post: 11912643 |
"The front panel contains one connector, J1, and a grounding stud. • J1 provides the main EAFR power supply, Aircraft Data Network, Ethernet Channels A and B, analog audio input, input and output discretes, and other miscellaneous signals." If RIPS is external and the GE EAFD only has a "main power supply" pin then I agree it seems likely that the flight data function is powered by RIPS. For RIPS to power only the CVR function I would have expected to see separate main power and RIPS power input pins. I could not find any data except the two page marketing brochure which is not definitive. |
AirScotia
June 29, 2025, 19:49:00 GMT permalink Post: 11913191 |
I've been travelling without access to internet, but I came across this video a few days ago. I don't know anything about the three guys, but they're apparently retired air accident investigators.
They seem to think that some of the EAFR data is now in the US. Is that actually the case? |
za9ra22
June 29, 2025, 20:02:00 GMT permalink Post: 11913197 |
There's no credible reasons 'three former accident investigators' in the US would have any direct knowledge, and if any third party in the US has been provided access to data, it will have been on the basis that it is not shared. Even that I would doubt, since involved parties are far more likely to already be in India as part of the investigation. On edit, and mindful of the Mods comments around the closing of the thread previously: I don't speak with any direct knowledge of accident investigations in India, only the UK - and even then with only one experience of civil aviation accident work. But I have been involved (in human factors as investigator and lead) in several UK incidents of scale, and have some familiarity with how these processes are constituted and work... there at least. Last edited by za9ra22; 29th June 2025 at 20:19 . Reason: Clarification |
Innaflap
June 30, 2025, 14:42:00 GMT permalink Post: 11913673 |
I am not aware of any requirement for a DFDAU (or equivalent) to store any data. I say "or equivalent" because in B717 the DFDAU is not an LRU. It is a functional partition of the VIA.
It's not clear to me that 787 EAFR even requires an external DFDAU. The GE EAFR does not - "Provides Flight Data Acquisition function of ARINC 664 p7 data parameters \x96 No need for a Digital Flight Data Acquisition Unit (DFDAU)." ref https://www.geaerospace.com/sites/de...rder-3254F.pdf |
KSINGH
July 11, 2025, 20:40:00 GMT permalink Post: 11919771 |
- fuel cut offs were found in the RUN position
- on take off roll both engines lost power as the fuel cut offs went from RUN to cutoff - CVR recorded one pilot asking why they had gone to CUTOFF - within 10 seconds the fuel cutoff was moved back to RUN -RAT was deployed, APU had begun auto start - 32 seconds after Vr the MAYDAY was called This should also dispel a lot of the comments about AAIB-India, Indian culture in general and general competence. For a preliminary report this is far more thorough and extensive than what would normally be expected and they\x92ve kept Boeing, GE, FAA and investigators from US, UK, Canada and Portugal in the loop from the start They have also clarified why it took so long to do the EAFR download- because of the extensive damage they had to source specialist equipment from the NTSB that only arrived on the 23rd of June (they downloaded on the 24th) so all that talk of a \x91coverup\x92 is pretty embarrassing now of course the big question is why/how those switches were commanded into cutoff in the first place the exact sequence at Vr is the most critical, there hasn\x92t been much scrutiny at all that I can see in the Indian/international media of the personal background of the flight deck crew which has happened in other suspected pilot initiated disasters in the past, I guess this is an avenue investigators will have been doing themselves |
Engineless
July 11, 2025, 20:40:00 GMT permalink Post: 11919772 |
The aircraft achieved the maximum recorded airspeed of 180 Knots IAS at about 08:08:42
UTC and immediately thereafter, the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec. The Engine N1 and N2 began to decrease from their take-off values as the fuel supply to the engines was cut off. In the cockpit voice recording, one of the pilots is heard asking the other why did he cutoff. The other pilot responded that he did not do so. The CCTV footage obtained from the airport showed Ram Air Turbine (RAT) getting deployed during the initial climb immediately after lift-off (fig. 15). No significant bird activity is observed in the vicinity of the flight path. The aircraft started to lose altitude before crossing the airport perimeter wall. As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The EGT was observed to be rising for both engines indicating relight. Engine 1’s core deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC As per the EAFR data both engines N2 values passed below minimum idle speed, and the RAT hydraulic pump began supplying hydraulic power at about 08:08:47 UTC. RAT in extended position 15 As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The EGT was observed to be rising for both engines indicating relight. Engine 1’s core deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC At about 08:09:05 UTC, one of the pilots transmitted “MAYDAY MAYDAY MAYDAY”. 08:08:42 Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position. One of the pilots asks the other why did he cutoff. The other pilot responded that he did not do so. 08:08:52 Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN 08:08:56 Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN Who (or what?) operated the cutoff switches? Last edited by Engineless; 11th July 2025 at 20:53 . |
thnarg
July 11, 2025, 21:32:00 GMT permalink Post: 11919837 |
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Kraftstoffvondesibel
July 11, 2025, 21:51:00 GMT permalink Post: 11919856 |
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DaveReidUK
July 11, 2025, 22:06:00 GMT permalink Post: 11919880 |
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Musician
July 11, 2025, 22:09:00 GMT permalink Post: 11919886 |
Seconds count:
As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about
08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN. When fuel control switches are moved from CUTOFF to RUN while the aircraft is inflight, each engines full authority dual engine control (FADEC) automatically manages a relight and thrust recovery sequence of ignition and fuel introduction. The EGT was observed to be rising for both engines indicating relight.
Engine 1's core deceleration stopped, reversed and started to progress to recovery.
Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC.
That was with 10 seconds delay vs. 13 seconds for engine 2.
Time was spent with the verbal exchange, and then perhaps each pilot expected the other to put the switch back? Anyway, the preliminary report also establishes that the aircraft had only 3-4 seconds of powered flight. (Would the gear lever be operated that early?) Everyone who saw that from the CCTV video, pat yourselves on the back. ![]() Mayday call, dual engine failure, RAT deployment all confirmed. TCMA was a red herring, the aircraft was firmly in air mode as the accident unfolded, and the thrust levers were at takeoff thrust the whole time. |
exBng Pilot
July 11, 2025, 23:14:00 GMT permalink Post: 11919977 |
The report states that
"the Engine 1 and Engine 2 fuel cutoff switches transitioned from RUN to CUTOFF position one after another with a time gap of 01 sec"
. It doesn't say at the start of the paragraph but if following from the previous paragraph then this information is sensed from the data recorder.
Again, from the report "As per the EAFR, the Engine 1 fuel cutoff switch transitioned from CUTOFF to RUN at about 08:08:52 UTC. The APU Inlet Door began opening at about 08:08:54 UTC, consistent with the APU Auto Start logic. Thereafter at 08:08:56 UTC the Engine 2 fuel cutoff switch also transitions from CUTOFF to RUN.". Again this is sensed from the data recorder. I would be interested to know whether sounds consistent with the actual fuel control switch being moved have been picked up on the voice recorder. |
physicus
July 12, 2025, 00:08:00 GMT permalink Post: 11920029 |
Timeline of known events with source attribution from the preliminary report:
08:07:33 ATC: Takeoff clearance 08:07:37 A-SMGCS: Aircraft starts rolling 08:08:33 EAFR: V1 153kts 08:08:35 EAFR: Vr 155kts 08:08:39 EAFR: Gnd-Air mode transition 08:08:42 EAFR: Max IAS 180kts, Eng 1/2 Cutoff switches activate within 1 second of each other 08:08:42 CVR: "Why did you cut off", "I did not" (exact time not specified) 08:08:42 A-SMGCS: RAT deployed (exact time not specified) 08:08:47 EAFR: Both engine N2 below min idle. RAT hyd pwr commences 08:08:52 EAFR: Eng 1 cutoff to RUN 08:08:54 EAFR: APU inlet door opens (auto start logic) 08:08:56 EAFR: Eng 2 cutoff to RUN 08:09:05 ATC: Mayday call 08:09:11 EAFR recording stops Fuel cutoff switches operated within 1 second of each other suggests to me that the locking mechanism wasn't working as per (SAIB) No. NM-18-33. Any loose item could have accidentally (or not) operated the switches (including hands). Last edited by physicus; 12th July 2025 at 00:24 . |
Pilot DAR
July 12, 2025, 00:50:00 GMT permalink Post: 11920045 |
08:08:52 EAFR: Eng 1 cutoff to RUN
08:08:54 EAFR: APU inlet door opens (auto start logic) 08:08:56 EAFR: Eng 2 cutoff to RUN 08:09:05 ATC: Mayday call |
Someone Somewhere
July 12, 2025, 01:00:00 GMT permalink Post: 11920049 |
If I recall correctly, the Mayday call was wording to the effect "thrust not achieved". That sounds like a phrase which could be expected from a pilot who had just frantically tried to restart an engine, and realized that it was not a success, and there would not be an opportunity for another attempt. The pilot aviated, (forget navigation), then communicated - over a period of 13 seconds.
The EGT was observed to be rising for both engines indicating relight. Engine 1’s core
deceleration stopped, reversed and started to progress to recovery. Engine 2 was able to relight but could not arrest core speed deceleration and re-introduced fuel repeatedly to increase core speed acceleration and recovery. The EAFR recording stopped at 08:09:11 UTC At about 08:09:05 UTC, one of the pilots transmitted “ MAYDAY MAYDAY MAYDAY ”. The ATCO enquired about the call sign. ATCO did not get any response but observed the aircraft crashing outside the airport boundary and activated the emergency response. #2 may or may not have eventually started successfully; the extra two seconds of no fuel meant it would be a much harder start for the FADEC. It doesn't sound like the crew have any input on the relight process; if the switch is on, the FADECs will try anything they can to get the engines lit and accelerating ASAP. Repeatedly switching between off and on will not help this process and there are basically no other controls the crew have, especially with no other power to run the engine starters. |
appruser
July 12, 2025, 01:28:00 GMT permalink Post: 11920070 |
Can someone with the engineering knowledge build a timeline/timeframe for fuel cutoff switch RUN to CUTOFF -> fuel stops -> engine flameout -> N2 drops to ? -> VFSGs quit -> RAT deployment starts -> RAT full power -> APU deployment start?
Does the RAT really start providing power in 4 seconds from the E2 fuel cutoff switch RUN -> CUTOFF? Timeline from AAIB and the public CCTV video: 08:08:33 v1 153 kts . 08:08:35 vr 155 kts . . . 08:08:39 Liftoff, A/G Air Mode, rotation at 00:18 in public CCTV video . . 08:08:42 E1 Fuel Cutoff Switch RUN -> CUTOFF, 180 kts 08:08:43 E2 Fuel Cutoff Switch RUN -> CUTOFF .............? N1 N2 begin to decrease .............? "Why did you cutoff", "I didn't" .............? Airport CCTV shows RAT .............? N2 < idle speed 08:08:47 RAT hydraulic power . 08:08:49 Public CCTV video: visible loss of thrust, Alt < 200ft using wingspan . . 08:08:52 E1 Fuel Cutoff Switch CUTOFF -> RUN, CCTV video: visible descent . 08:08:54 APU inlet door begins opening . 08:08:56 E2 Fuel Cutoff Switch CUTOFF -> RUN 08:09:05 MAYDAY 08:09:11 EAFR Recording stops 08:14:44 Crash Fire Tender leaves airport Last edited by appruser; 12th July 2025 at 01:29 . Reason: readability |
Someone Somewhere
July 12, 2025, 01:47:00 GMT permalink Post: 11920083 |
Spoiler
It seems like people are jumping to conclusions about the pilots and letting Boeing off the hook without proper investigation. Instead of providing a professional, detailed transcript of the cockpit voice recorder (CVR), we’re just getting casual comments about what the pilot allegedly said. Critical information—like the timing of transmissions, the checklist items completed before takeoff, and other key details that should be on the CVR—are essential for understanding what happened in the cockpit, especially since the crash occurred so soon after takeoff. In my view, the preliminary report feels too convenient for certain parties involved.
Examining the before-takeoff checklists seems like it would be akin to examining the re-arrangement of the deckchairs before the titanic even hit the iceberg. The engines were switched off. Unlike Embraer, B & A have no protections stopping you switching an engine off inadvertently. From everything in the report, everything operated exactly as designed. I am not certain of how long the relight window is without windmilling speed, but +- 10 seconds seems entirely reasonable. The outstanding question that presumably requires much more in-depth investigation of the wreckage items and CVR audio is whether:
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Someone Somewhere
July 12, 2025, 02:02:00 GMT permalink Post: 11920093 |
Consider
this post
with a picture of the switches in question:
![]() They must be lifted over the detent (if installed correctly) in each direction. For reference, it's pretty common for industrial emergency stop buttons to have 2-3 poles: redundant poles for the actual fault switching (legislative requirement above certain hazard levels), plus an additional pole for monitoring. Depends on when they identified the SB and how obvious the lack of or incorrect fitting of detents is. |
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