Posts about: "Gear Retraction" [Posts: 243 Pages: 13]

StuntPilot
2025-06-15T18:15:00
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Post: 11902683
Originally Posted by sorvad
Visual evidence the rat was deployed, audio evidence the rat was deployed, evidence the APU inlet door was open, evidence the gear retraction was interrupted, evidence there was very little engine noise after departure, very obvious evidence that the aeroplane didn\x92t have enough thrust to stop it descending into the ground. All of this strongly suggests that both engines were to all intents and purposes, and for want of a better word, \x91failed\x92 now that could be intentional, accidental or because of some sort of technical malfunction or external factor. Nothing conclusive and no answers as to how or why, but not quite as wildly stabbing in the dark as your post would infer.
We agree that there was a lack of thrust. Possibly caused by a dual engine failure. But the sharpest frames in the video do NOT show the RAT and this is counter evidence to the RAT theory. If there were substantial technical failures who knows what sounds could be generated. I find the evidence weak at best. And we immediately get into a chicken-egg problem: did some power issue of unknown nature cause an engine failure or did a dual engine failure occur, resulting in a power loss? Both are extremely unlikely and need to be backed by quality evidence. The video is not it, in my opinion. I don't know the APU intake mechanism and whether it could open after the impact.

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DCT_ELSIR
2025-06-15T18:17:00
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Post: 11902685
I don't mean to quote myself, but does anyone know why I have seen BA departures not raising the wheels? Is this is a previous thing or a current thing?
I’m an ex-787 pilot. There are a number of defects on the 787 where you can dispatch under the MEL with an operational procedure that requires the gear to be left down for varying amounts of time after takeoff. You probably saw an aircraft that was carrying one of these defects. Routinely leaving the wheels out to cool the brakes isn’t really a thing on the 787, despite lots of spotters thinking it is. In normal operations if you see a 787 with the wheels left out after takeoff it’s almost certainly dispatched legally under the MEL and carrying out the associated operational procedure.

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ciclo
2025-06-15T18:52:00
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Post: 11902715
The report of a seat back collapsing on rotation is a poorly rehashed version of the completely unrelated Air India Express flight 611 in October 2018. That flight did have a captain seat collapse on takeoff causing it to take off with reduced thrust, flying its landing gear through the localizer array and airport perimeter wall. But it eventually diverted and landed safely with no injuries. There are even YouTube videos about it, e.g. search YouTube for "Boeing 737 flies through brick wall".

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ManaAdaSystem
2025-06-15T19:59:00
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Post: 11902779
Regarding the flashing green and white lights. On Airbus aircraft the emergency exit lights come on when the gear is down, and goes out when the gear is raised. Is this also the case on the 787?
if so, if the gear is/stays in transit (as the gear tilt may suggest) can this make the exit lights cycle on and off?
Just a thought.

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Tu.114
2025-06-15T21:17:00
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Post: 11902850
The electrical failure is rather a chicken-egg question.

Not knowing the 787, I\xb4d find it extremely hard to believe that a massive electrical failure would kill the engines. I gather from this thread that the landing gear retraction is driven by the electrically-powered Center hydraulic system. Retracting the gear is hard work for the system and it will put a strain on the two pumps and their supplying electric circuits, and the time of the alleged total power loss would seem to be in the vicinity of the suitable time to retract the gear.

But if there was some freak epidemic failure this inflicted upon the aircraft electrics, it is hard to imagine that this would affect both engines. There are still the autonomous FADEC governing them that run on their own internal generators (with a small external power source from the main systems, should the permanent magnet alternators fail) and do everything they can to keep the engine alive. As long as there is fuel flowing into the feed pipes, the engine should be kept running by the FADECs, and that this does not require the large tank pumps at low altitudes has been established in this thread.

Consequently, I\xb4d deem it plausible that the alleged power failure must have been a consequence of whatever happened to the engines. After all, the engines drive the available generators at this stage of flight, the APU with its additional generators is apparently not run for takeoff on the 787. I find it logically much easier to wrap my head around a situation in which an engine failure takes along the generators than one in which a massive, epidemic electric breakdown kills the engines.
Captain Fishy
2025-06-15T21:56:00
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Post: 11902882
Originally Posted by bakutteh
Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners\x92 imagination.😖🥴😬

A loss of lift AND thrust at this critical juncture could have had caused this awful disaster. I think the data recorders have already revealed the cause but If it's this, then I don't think we will hear much anytime soon.
DIBO
2025-06-15T22:27:00
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Post: 11902910
Originally Posted by The Ancient Geek
Lots of noise about RAT, gear doors, pilot seats, etc,etc,etc.
The RAT being deployed or not, is an essential factor.
But indeed, a lot of noise is being generated by some that continue to simply ignore the professional sound analysis provided already 600+ (surviving) posts ago, without any relevant counter-arguments or proof (other than some low quality video).

(And I don't mind this sound analysis to be proven invalid, but then only with similar professional skills and counter arguments.)

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kit344
2025-06-15T22:59:00
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Post: 11902936
TCMA Logic

Retired RAF avionics technician, PPL / Glider pilot with ~ 700 hrs. VC10 double EFATO survivor.

The TCMA system should be inhibited when Air / Ground logic is in Air mode.
I understand that it has Inputs from RadAlt, Weight on Wheels, etc.
This airframe was reported to have had a history of significant electrical / electronic problems, including on the prior inbound flight.
There may have been water ingress in the E&E bay, likely causing corrosion or other damage.
Chafed or damaged wiring / cable insulation within looms is possible. Including the landing gear microswitches.
The landing gear may have been interrupted in the cycle.
BOTH engines are reported to have shut down, so whatever happened is a system common to both engines.
TCMA failing at the moment of gear retraction appears to fit with the available evidence.

Last edited by kit344; 15th Jun 2025 at 23:03 . Reason: they there replacement

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tdracer
2025-06-16T00:01:00
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Post: 11902989
Originally Posted by syseng68k
FrequentSLF: I would be more suspicious of the hardware that feeds TCMA. Rad Alt sensing could be in error, but possibly more likely is the hardware that senses weight on wheels. May be position sensing microswitches, or perhaps gear oil pressure, but would assume redundancy, eg: two sensors per leg, then some sort of voting logic on the sensor set to find faulty hardware.and make a decision. Doubt if the software is at fault, but is there a delay between sensor output, and command to shutdown the enigines ?. Alluded to doubts upthread, but I think the post was deleted. Question: Should TCMA really have the absolute power to auto shutdown engines at all, without some sort of confirmation ?.
On the 747, Weight on Wheels (WoW) depends on prox sensors on the landing gear (i.e. gear compression). I don't know how that's done on the 787.
The reason we used both Radio Alt and WoW is that both can give erroneous indications on certain conditions - RA can be 'fooled' by dense rain or even really dense fog (the signals bounce off the water and falsely indicate on-ground), the prox sensor system can subject to HIRF/Lightning interference.

TCMA acts quickly, but it does require some persistence, so an input glitch won't activate it (mainly N1, which is measured every 15 milliseconds).

What sort of 'confirmation' do you have in mind - the regulator mandate that resulted in TCMA basically says we can't take credit for the flight crew.

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AndyJS
2025-06-16T01:10:00
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Post: 11903023
This has just appeared in the Times (of London) which is usually one of the most reliable sources of information in the UK.

"A loss of engine power is emerging as the most likely cause of the crash of the Air India Boeing that killed at least 279 people at Ahmedabad on Thursday. The Boeing 787-8 series appeared to have suffered from lower than normal thrust from its General Electric GEnx engines as it took off and failed to climb more than 450ft before crashing, video and reports from the Indian authorities have indicated.The new information has eclipsed an early focus on the unusual configuration of the aircraft\x92s wing flaps and landing gear."

https://www.thetimes.com/world/asia/...rash-vhqw6b7v3

(subscription required to read the article)

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OldnGrounded
2025-06-16T01:40:00
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Post: 11903037
Originally Posted by AndyJS
This has just appeared in the Times (of London) which is usually one of the most reliable sources of information in the UK.

"A loss of engine power is emerging as the most likely cause of the crash of the Air India Boeing that killed at least 279 people at Ahmedabad on Thursday. The Boeing 787-8 series appeared to have suffered from lower than normal thrust from its General Electric GEnx engines as it took off and failed to climb more than 450ft before crashing, video and reports from the Indian authorities have indicated.The new information has eclipsed an early focus on the unusual configuration of the aircraft\x92s wing flaps and landing gear."

https://www.thetimes.com/world/asia/...rash-vhqw6b7v3

(subscription required to read the article)
Thanks for the heads up. The story also says, "No cause has yet been identified for what would be an extremely rare power loss from both engines, but on Sunday the Indian civil air authority (DGCA) began urgent pre-flight inspections of fuel systems, electronic engine controls and other systems on Indian Boeing 787s."

And it quotes Juan Browne (Blancolirio): \x93There was something terribly wrong with this 787 jet and we need to find out really quickly what went wrong because we\x92ve got a thousand of these operating today and operators need to find out what happened.\x94

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DTA
2025-06-16T05:52:00
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Post: 11903115
Originally Posted by tdracer
On the 747, Weight on Wheels (WoW) depends on prox sensors on the landing gear (i.e. gear compression). I don't know how that's done on the 787.
The reason we used both Radio Alt and WoW is that both can give erroneous indications on certain conditions - RA can be 'fooled' by dense rain or even really dense fog (the signals bounce off the water and falsely indicate on-ground), the prox sensor system can subject to HIRF/Lightning interference.

TCMA acts quickly, but it does require some persistence, so an input glitch won't activate it (mainly N1, which is measured every 15 milliseconds).

What sort of 'confirmation' do you have in mind - the regulator mandate that resulted in TCMA basically says we can't take credit for the flight crew.
Where does the logic block that takes the WoW and other inputs to generate the singe air/ground indication live? Is it somewhere that would be affected by the aircraft power systems? Could a failure in the aircraft power cause a false ground indication to be sent to the FADECs?
Compton3fox
2025-06-16T09:41:00
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Post: 11903328
Originally Posted by FlyingUpsideDown
The PF could've been task focused flying manually, following the FD's and not expecting the sinking feeling of losing the lift. The PM has made the mistake without knowing. ie. he/she has selected the flaps all the way to UP believing that the gear was now retracting. Both pilots now think the gear is retracting, they have full thrust but are sinking into the ground. "Professional crews" like Air France for eg. have made way worse decisions. Slats are extended because they are the last to retract. I'm not convinced the RAT is deployed. If it has deployed it could've been a last ditch effort for the crew to bring the fuel control switches from RUN to CUTOFF & back to RUN believing they've had a dual engine failure. This would account for the RAT if it did deploy. The APU inlet door could've been open as well because they were carrying out an APU to Pack takeoff. Once the aircraft is airborne and the weight-on-wheels (WOW) switches indicate air mode , the main gear bogies automatically tilt to the neutral position before retraction. Also when the flaps passed the last takeoff position on the quadrant, the Landing gear configuration warning horn would've sounded further confusing the pilots.
If you read the thread, you would know:

The RAT was almost certainly deployed. 4 different sources.
The Flaps were not retracted. Visible at the accident site plus many other sources agreeing they were indeed down.
APU will autostart when all engine power is lost. Potentially explaining why the inlet door was open or partially open at the accident site. Mentioned in several previous posts
On a 787-8, the main bogies tilt as the 1st action of the gear retract sequence. As stated in previous posts. I don't think this happens unless gear is selected up. So the conclusion was, gear was selected up. One caveat, IIRC, there was some discussion around a failure could have caused the bogies to tilt without Gear up being selected but I don't recall the outcome.
As for the Air France remark, un-necessary IMHO. Let's respect the crews please.


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Airboard
2025-06-13T01:01:00
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Post: 11903706
Originally Posted by Airboard
Yes. But I have not flown this scenario in the sim. Way too many protection to take off without proper configuration which leads me to believe loss of lift due to flap retraction. 1100 hr FO \x85\x85..
I\x92ll reply to my own post in light of the RAT deployment. If true then this opens up to a lot more. And simply guessing with grainy video a fools game. All I saw was gear down to high Into the climb. This should not happen under any circumstance . Dual engine failure would explain the loss of lift obviously. Early flap retraction also. One would hope it\x92s not a simple as that: cheers
Icarus2001
2025-06-13T05:11:00
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Post: 11903710
An engine failure just off the runway after V1 in a fully loaded 787-8 in high ambient temperatures would assuredly have a crew thinking about a "toute suite" shutdown of a misbehaving donk
No, no, no and again no.

This is a transport category aircraft. It will happily climb on one engine to a safe altitude where procedures are followed.

There is zero evidence of any engine "failures" or shutdowns by the crew.

However the gear is still down at around 500' agl.

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fdr
2025-06-13T22:13:00
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Post: 11903712
Originally Posted by Turkey Brain
At this stage, at least two scenarios seem highly plausible:

1. Technical issue

Airliners rely on air/ground logic , which is fundamental to how systems operate.

There have been numerous crashes and serious incidents linked to this logic functioning incorrectly.

Some engineering tests require the air/ground switch to be set in a particular mode. If it's inadvertently left in engineering mode—or if the system misinterprets the mode—this can cause significant problems.
  • On the ground , if the aircraft is incorrectly in air mode , some systems may be unavailable—such as wheel brakes, reverse thrust, or ground spoilers.
  • In the air , if the aircraft is mistakenly in ground mode , flaps might auto-retract, and various layers of system protection may be disabled.
In the case of the ANA 787, it appears the engine shutdown occurred during the landing roll, possibly when the TCMA system activated.

2. Pilot misselection of fuel control switches to cutoff

This is still a very real possibility. If it occurred, the pilot responsible may not have done it consciously—his mindset could have been in a different mode.

There’s precedent: an A320 pilot once inadvertently shut down both engines over Paris. Fortunately, the crew managed to restart them. Afterward, the pilot reportedly couldn’t explain his actions.

If something similar happened here, then when the pilots realized the engines had stopped producing thrust, pushing the levers forward would have had no effect. It’s easy to overlook that the fuel switches are in the wrong position—they're far from the normal scan pattern. And with the ground rushing up, the view outside would’ve been far more commanding.

Speaking personally, when I shut down engines at the end of a flight, I consciously force myself to operate each fuel switch independently and with full attention. I avoid building muscle memory that might lead to switching off both engines in a fast, well-practiced habit.

If this is a technical issue, I assume we’ll know soon enough.
On item 1, the TCMA issue should have been fixed, it does fit the sort of issue that occurred here. TDRACER can talk to that, and has done in 2019 and again in post 792. As to flap auto retraction, the B787 like all Boeings has a gated flap lever, and the flaps are only able to move independent of the lever by flap load relief. That would not have caused a loss of thrust, and in this case it is evident that the event is a thrust loss not a CL loss.

On item 2, the video shows no asymmetry at any time, so there is only a symmetric failure of the engines possible. Back on a B747 classic, you could chop all 4 engines at the same time with one hand, on a B737, also, not so much on a B777 or B787. I would doubt that anyone used two hands to cut the fuel at screen height. Note, there was a B744 that lost one engine in cruise when a clip board fell off the coaming. Didn't happen twice, and it only happened to one engine.


Originally Posted by neila83
Yes indeed, the moment they pulled the gear lever, as we see the gear begin the retraction process, and then suddenly stop. Almost as if they suddenly lost power.

We can see the landing gear retraction process begin. We see the bogies tilted in the second video. We can hear the RAT. We can see the RAT. We can see the flaps extended in the video and at the crash site. There isn't actually a single piece of evidence the flaps were raised, it's just a conclusion people jumped too before evidence began to emerge.

The crazy thing is, when the report comes out and there is no mention of flaps none of the people who have been pushing the flap theory will self reflect or learn anything. They'll think those of us who didn't buy into it were just lucky, rather than it being down to use of fairly simple critical thinking.
​​​​​
Neila83 is correct, the gear tilt pre retraction is rear wheels low, and at the commencement of the selection of the retraction cycle (generally), the first thing that happens is the inboard MLG doors start to open below the wheel well and then the bogie is driven to front wheels low. (There is also an option that the inboard gear doors start to open early as a result of WOW sensing to improve the SSL climb limit). [my bad, for the B788 Capt Bloggs informs us the gear door sequence is after the tilt, not before, the B789 has the before tilt, the option for the door open at rotate is separate]

The inboard doors do not appear to have opened in this case, yet, the gear is forward wheels down. This appears to be out of sequence. TD may have better knowledge on the options that exist with the B788, but this is not looking good at this time.

There is enough in the way of anomalies here to end up with regulatory action, and airlines themselves should/will be starting to pore over their systems and decide if they are comfortable with the airworthiness of the aircraft at this moment. A latent single point of failure is not a comfortable place to be. Inhibiting TCMA might be a good interim option, that system could have been negated by having the ATR ARM switches....(Both)... ARM deferred to the before takeoff checks. The EAFR recovery should result in action within the next 24-48 hours. Boeing needs to be getting their tiger teams warmed up, they can ill afford to have a latent system fault discovered that is not immediately responded to, and the general corporate response of "blame the pilots" is not likely to win any future orders.

I think we are about to have some really busy days for the OEM.


Originally Posted by Right Way Up
I think you need to temper your tone This is a discussion about possibilities and quite honestly nothing would surprise me. There is no "winning" result here. Just hopefully answers which will help safety in the future.
Not sure that Neila83 is that far off the mark at all.
KSINGH
2025-06-14T08:43:00
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Post: 11903718



I’m not a 787 driver so for fear of looking dumb in front of those that are this still confuses me. Even IF they’ve mis-selected the flap setting (I still don’t think it’s been cemented on here that there is in fact a FMS/flap setting disagreement warning but i believe there is), had the wrong de-rated take off settings, selected flaps instead of gear up the 787 with massive high bypass engines, FBW and full envelope protections surely cannot let itself be put in such a low energy/high alpha regime as we saw in the videos IF it has both fans functioning normally, surely?

the pilots may have messed up royally and numerous times so those holes lined up but the plane is the final block in the chain and a 21st century all digital entirely clean sheet design was sold as being immune to such catastrophic outcomes from a few minor (consequential yes) and fairly common errors- aren’t all the protections and our procedures designed after decades of mistakes?

im having a hard time squaring how a fully functioning modern bird like this could allow for this outcome and almost whatever the pilots did outside of unbelievable inputs and the pilots are are a bit of a red herring IMO


Dale Winsley
@Winsleydale
No. The LE slats are deployed therefore the flaps are as well. This is an automatic linkage. The flaps are set at Take-Off. Hard to see from the angle but they are...if slats are out (easy to see) then flaps are set. Looks like Flaps 5. Also, the 787 has the highest Thrust-to-Weight ratio of any airliner on Earth. The change in Alpha and lift is a trifling matter for it, at these settings (1-5). It will fly out of it easily, even at that density altitude. The attitude change is - in the circumstances I describe, consistent with a massive power loss (both sides). I believe based on probability that simultaneous mechanical failure is not the cause. Fuel contamination or starvation is likewise unlikely based on the 787 fuel system. The common element is the FADEC/Autothrottle/TOGO. However, each engine FADEC is dual redundant two channels. So any such common failure must happen further upstream. From a design perspective, that would be unthinkable. But this is Boeing. Given what I can see with my own eyes, I believe the flap issue is a non-starter. Also, re the landing gear: Clearly the Positive Rate challenge would be met based on normal rotation and fly-off at V2. But since we know the flaps were set correctly, that rules out an "oopsie" moment. Just as likely there was at the challenge moment an indication that something was amiss, and the Gear Up call was not made. They see both N1s unwinding and it takes a second to get past the WFT factor. They cross-check and see the airspeed also unwinding. Then they unload the Alpha and pitch to gear down Vy. And they had another 6 seconds. Whatever it was, it was not a flap, mechanical or fuel issue. We will know soon enough. But this is Boeing. My gut says "software". All 787s worldwide need to be grounded, now.
6:10 AM \xb7 Jun 14, 2025
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fox niner
2025-06-15T12:51:00
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Post: 11903781
777/787 driver here.

Reading a few posts about an APU-to-pack takeoff, or a packs off takeoff on a 787, because of the hot weather, makes me shake my head.
There is no bleed air on the 787. A packs off takeoff, or an apu to pack takeoff, is never done. There isn’t a procedure in the fcom to describe it. It is also pointless. The packs are electrical.

Then the gear.
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.

takeoff performance:
I entered all relevant weather parameters into my performance tool for Ahmedabad VAAH, rwy 23, 42 degrees C and no wind, qnh 1005.
It comes up with flaps 10 as optimum, albeit for a 787-9 (don’t have the possibility to calculate for the 787-8) But even the 787-9 is able to depart with flaps 5 in those conditions. Max tow around 230tons.

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Roo
2025-06-15T13:14:00
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Post: 11903886
Originally Posted by fox niner
777/787 driver here.

Then the gear.
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..
Incorrect. Aircraft is a 787-8. It is does not have the early MLG door opening feature fitted to 787-9 & -10.
Roo
2025-06-15T16:36:00
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Post: 11903887
Originally Posted by D Bru
I'm posting some YT-links to show that 787-8 and -9 gear doors seem to behave similar only when electing to actually retract the LG….
Well I am sorry but they don’t.
This yt video is somewhat cheesy, but it should make the -9 “early open” MLG door process clear to you, in a normal gear retraction. Unless you think this clown selected gear up on the ground.
They cycle open before gear is selected up (& even if gear is left down as you observed). Whereas on the -8 MLG doors will not budge until gear is selected up.