June 13, 2025, 19:38:00 GMT
permalink Post: 11900843
SLF, so probably stupid question: Why don't companys like Airbus or Boeing integrate scales in their planes? Not to make calculation of lift of weight of calculations are wrong? Why don't they integrate systems that hinder you from retracting flaps in the first 20 to 30 seconds after the landing gear lost contact to the ground etc?
What I am trying to say: There are pretty simple logics that could be integrated that would presumably kill many discussions held here.
What I am trying to say: There are pretty simple logics that could be integrated that would presumably kill many discussions held here.
Subjects: None
June 15, 2025, 09:10:00 GMT
permalink Post: 11902268
TCMA requires the a/c to believe it is on the ground (via multiple redundant inputs, both weight on wheels and radalt). I do not know if there is also a max activation speed.
I posited a potential TCMA sequence in a post timed 1804Z - speculative of course. Agree with others, it is difficult to contemplate and seems staggeringly unlikely.
I posited a potential TCMA sequence in a post timed 1804Z - speculative of course. Agree with others, it is difficult to contemplate and seems staggeringly unlikely.
Any thoughts?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): APU Weight on Wheels
June 19, 2025, 07:22:00 GMT
permalink Post: 11905790
There seem to be issues with the evaluation due to damages. Cannot assess the reliability of the source.
https://weeklyvoice.com/damaged-blac...medium=twitter
https://weeklyvoice.com/damaged-blac...medium=twitter
The black box from the Air India flight AI171 that crashed in Ahmedabad on June 12 has been found damaged and may need to be sent to the United States for further data retrieval, according to government sources. Officials indicated that the final decision will rest with the Indian aviation authorities, but the device could be flown to Washington DC for evaluation by the U.S. National Transportation Safety Board (NTSB).
Technically, the “black box” includes two crucial components: the Cockpit Voice Recorder (CVR) and the Flight Data Recorder (FDR). These devices are essential for reconstructing the events leading up to the crash, offering both voice recordings from the cockpit and a detailed record of the aircraft’s flight parameters. Due to damage sustained in the crash and fire, India may require the specialized equipment and expertise of the NTSB to recover and interpret the remaining data.
If the device is sent abroad, a team of Indian officials is expected to accompany it to ensure compliance with all security and procedural standards throughout the process.
Technically, the “black box” includes two crucial components: the Cockpit Voice Recorder (CVR) and the Flight Data Recorder (FDR). These devices are essential for reconstructing the events leading up to the crash, offering both voice recordings from the cockpit and a detailed record of the aircraft’s flight parameters. Due to damage sustained in the crash and fire, India may require the specialized equipment and expertise of the NTSB to recover and interpret the remaining data.
If the device is sent abroad, a team of Indian officials is expected to accompany it to ensure compliance with all security and procedural standards throughout the process.
Last edited by Senior Pilot; 19th June 2025 at 08:19 . Reason: Add quote; please don’t just post hyperlinks
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): AI171 CVR FDR NTSB Parameters
June 19, 2025, 09:30:00 GMT
permalink Post: 11905864
https://ad.easa.europa.eu/blob/NM-18...SIB_NM-18-33_1
The FAA recommends that all owners and operators of the affected airplanes incorporate the following actions at the earliest opportunity: 1) Inspect the locking feature of the fuel control switch to ensure its engagement. While the airplane is on the ground, check whether the fuel control switch can be moved between the two positions without lifting up the switch. If the switch can be moved without lifting it up, the locking feature has been disengaged and the switch should be replaced at the earliest opportunity.
Last edited by Senior Pilot; 19th June 2025 at 11:13 . Reason: Image
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FAA Switch Guards
June 19, 2025, 12:27:00 GMT
permalink Post: 11905984
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.
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.
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.
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.
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 Fuel Cutoff Switches (detent)
June 19, 2025, 14:08:00 GMT
permalink Post: 11906053
I have read most of the thread (old and new). As a lawyer working in forensic investigations, I am constantly involved in problem-solving. My field of work also includes complex investigations related to insolvencies, which almost always require an analysis of the causes behind a specific, established outcome. In doing so, I naturally also have to deal with probabilities. However, it often turns out that the most likely or plausible explanation does not reflect what actually happened.
Many of the considerations I’ve read fail because the simultaneous failure of both engines is extremely unlikely, leading to a constant search for higher-order causes. It was suggested that an incorrect altitude setting led to an early thrust reduction. However, this would not explain the deployment of the RAT (Ram Air Turbine), especially since the thrust could have been readjusted. FADEC and TCAM are highly redundant systems, and TCAM failure is unlikely due to WOW (Weight on Wheels) logic, making a simultaneous engine failure after VR equally improbable.
With that said, and with regard to my question concerning the AD that relates to the fuel control switches (FCS), my thought—and it was nothing more than that—was that their activation becomes more probable if it can occur accidentally. That’s how I came across SAIB: NM-18-33.
Another user then brought up an iPhone. That notion would, of course, be dramatic—but how unlikely is it really that after approximately 10,000 actuations between December 2013 and June 2025, the two FCS no longer lock perfectly? Considering all of this, I find it quite conceivable that the A/T slightly reduced thrust in the first seconds after VR (e.g., if an incorrect target altitude had been entered) and that an object lying between the thrust levers and the FCS could have pushed the FCS into the “Off” position. Due to the buttons on top of the switches, which provide some resistance, it’s even possible that the object both pulled and pushed them.
But all of this is speculation. The investigation report will bring clarity.
Even if my theory is not confirmed, I still believe that the positioning and mechanism of the FCS are suboptimal. Switches of such critical importance should be better protected, and movements in the area in front of the switches (like reducing thrust) should not follow the same direction as shutting off the fuel supply. A different switching direction alone would provide more safety—especially considering that the FCS are protected laterally by metal plates.
Many of the considerations I’ve read fail because the simultaneous failure of both engines is extremely unlikely, leading to a constant search for higher-order causes. It was suggested that an incorrect altitude setting led to an early thrust reduction. However, this would not explain the deployment of the RAT (Ram Air Turbine), especially since the thrust could have been readjusted. FADEC and TCAM are highly redundant systems, and TCAM failure is unlikely due to WOW (Weight on Wheels) logic, making a simultaneous engine failure after VR equally improbable.
With that said, and with regard to my question concerning the AD that relates to the fuel control switches (FCS), my thought—and it was nothing more than that—was that their activation becomes more probable if it can occur accidentally. That’s how I came across SAIB: NM-18-33.
Another user then brought up an iPhone. That notion would, of course, be dramatic—but how unlikely is it really that after approximately 10,000 actuations between December 2013 and June 2025, the two FCS no longer lock perfectly? Considering all of this, I find it quite conceivable that the A/T slightly reduced thrust in the first seconds after VR (e.g., if an incorrect target altitude had been entered) and that an object lying between the thrust levers and the FCS could have pushed the FCS into the “Off” position. Due to the buttons on top of the switches, which provide some resistance, it’s even possible that the object both pulled and pushed them.
But all of this is speculation. The investigation report will bring clarity.
Even if my theory is not confirmed, I still believe that the positioning and mechanism of the FCS are suboptimal. Switches of such critical importance should be better protected, and movements in the area in front of the switches (like reducing thrust) should not follow the same direction as shutting off the fuel supply. A different switching direction alone would provide more safety—especially considering that the FCS are protected laterally by metal plates.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives Engine Failure (All) FADEC Fuel (All) Fuel Cutoff Switches RAT (All) RAT (Deployment) SAIB NM-18-33 Special Airworthiness Information Bulletin Weight on Wheels
June 19, 2025, 14:54:00 GMT
permalink Post: 11906089
Absolutely, if the correct "catch" is part of regular maintenance; is it? Besides this: It\xb4s all about errors, isn\xb4t it?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Maintenance Error
June 19, 2025, 15:04:00 GMT
permalink Post: 11906096
this isn\x92t the type of switch fitted to the 787 as a fuel control switch, totally irrelevant but has generated yet more nonsense. The switches are spring loaded (or so it feels) in addition to having a massive block to prevent inadvertent operation in either direction. Anyone suggesting they could be accidentally \x93knocked off\x94 is so clueless about their operation it\x92s actually painful to rebut
Subjects: None
June 19, 2025, 21:08:00 GMT
permalink Post: 11906375
So why the AD back in 2018?
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives
June 20, 2025, 23:18:00 GMT
permalink Post: 11907389
Sorry but that doesn't really make sense. Once the power failed and all pumps are off where is the point of switching of the center fuel pumps off? Without power they aren't running anyways.
Furthermore the preference of the center tank while it's filled is just by the higher fuel pressure those center pumps deliver. There is no valve that controls that, which might be triggered by switching off pumps.
Furthermore the preference of the center tank while it's filled is just by the higher fuel pressure those center pumps deliver. There is no valve that controls that, which might be triggered by switching off pumps.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Centre Tank Electrical Failure Fuel (All)
July 11, 2025, 22:12:00 GMT
permalink Post: 11919889
Spoiler
I wouldn't put too much significance in the "01 second" since this still is close enough for an unintentional cause.
No matter what: The design and position of the fuel cut off switches is potentially prone for mishaps.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Air Worthiness Directives Engine Failure (All) FADEC Fuel (All) Fuel Cutoff Fuel Cutoff Switches RAT (All) RAT (Deployment) SAIB NM-18-33 Special Airworthiness Information Bulletin Weight on Wheels
July 12, 2025, 11:49:00 GMT
permalink Post: 11920556
If the thrust levers were found in idle but, according to the EAFR, were set to TO thrust until the end, doesn\x92t that also raise further questions? I mean: Of course, the impact causes compression at the nose, but the centrifugal forces act in the opposite direction. So, if there is an objective inconsistency here, and we have a pilot who says he did not operate the fuel cut-off switches, while the EAFR indicates otherwise, then we have yet another inconsistency.
Relevant section in the preliminary report
Relevant section in the preliminary report
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR Fuel (All) Fuel Cutoff Fuel Cutoff Switches Preliminary Report
July 13, 2025, 12:23:00 GMT
permalink Post: 11921283
(SLF / Lawyer) I wrote early in the old thread that realistically only the FCS could be considered, pointing to the bulletin and suggesting that a foreign object might have affected both FCS simultaneously. After everything I've read here, I stick to that. Why? If the F/O was the PF, then only the PM could have operated the FCS. An unconscious action seems unlikely because it would have required not one but two unconscious actions, even if in quick succession. I consider that rather improbable. If it was a conscious action, wouldn\x92t the captain have taken over the flight instead? Unless one argues that the FCS had the lowest threshold and promised the safest outcome in this situation. Pilots could probably assess that better. But: How would it have turned out if the PF had reacted immediately and switched the FCS back on? Would the aircraft have been salvageable? If so, wouldn\x92t the PM have wanted to prevent this scenario and re-deactivated the FCS in Cut off position? In short: I think there are safer methods. Or am I mistaken?
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