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Quote:

Originally Posted by Sycamore

As an ex-tp, I would consider those cut-off switches a danger, and they should have guards either side of each.
Shirtsleeves/watches etc. can get caught, lift switch.
Very poor design. Would not pass `military-muster.`

Agree. The two most important controls in the aeroplane, sitting there in a wide-open, unprotected space. After an incident where a manual fell off the coaming (can't remember if a switch got bashed into the Off position), we put guards on our non-787 fuel switches:
Ours:

787:

Subjects Fuel (All)  Fuel Cutoff Switches  Switch Guards

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Quote:

Originally Posted by Lead Balloon

Not suggesting you are wrong, but are you sure it's not the other way around? 200' for the 777 and 400' for the 78? Maybe I've misinterpreted earlier posts on the subject.

According to the FCOMs I have, the minimum autopilot engagement height after take-off is 200 ft AGL for both types.

B777:


B787:

Subjects: None

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The 787 fuel controls do have guards on each side but they're hard to see in the photo I posted. Here's a better angle:

Subjects Switch Guards

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Quote:

Originally Posted by Europa01

I\x92ve had a look at the Honeywell spec sheet for TL type switches. They are a common type with many available configurations and are essentially a normal looking snap action switch. The locking feature is an add-on which can be specified. I have to say that from the diagrams, the locking mechanism doesn\x92t look that robust and I\x92d guess that it is subject to wear which was probably the basis of the SAIB. Given that this is a mechanical locking device seeing frequent use possibly with less than full mechanical sympathy it is possible to see how wear could occur. This does beg the question of how whether a check on the mechanism has made it into maintenance routines. ( Note - the locking mechanism appears to be the same for all TL switch types) . Those familiar with the switches - what do you think?

The generic version in your drawing has the centre position, whereas the version used on the 787 (4TL837-3D) has centre lockout. This photo shows the switch. You can see it is pretty easy to not place it in the locked positions. With this design of switch the cam on the toggle will eventually wear away.

Subjects Condolences  Honeywell  Special Airworthiness Information Bulletin

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Quote:

The RAT is an electrical generator, not a hydraulic pump. How many times does this need to be said?

To make things clear, just check this B787-related alert service bulletin dated 25 Nov 2014 (my bold):

Quote:

This service bulletin provides instructions to replace the Ram Air Turbine (RAT) Pump and Control Module
Assembly to prevent failure of the hydraulic pump at low air speed. The RAT Assembly provides an emer-
gency source of electrical and hydraulic power for the primary flight control if the left, center and right main
hydraulic systems fail. Loss of the RAT Pump and Control Module Assembly could lead to loss of control
of the airplane when emergency power from RAT Assembly is needed. If this change is not incorporated
on the RAT Assembly and hydraulic power is lost on the left, right and center main hydraulic systems, then
the RAT Assembly may not provide sufficient hydraulic power which could result in the loss of many critical
control systems that are necessary for safe flight.

787 RAT hydraulic pump location

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Last edited by Senior Pilot; 19th June 2025 at 12:40 . Reason: Image

Subjects Generators/Alternators  Hydraulic Failure (All)  RAT (All)  RAT (Electrical)

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DTA: Switch Movement

Sorry to disagree.

Have a few of that type here, so here's an up close pic of the toggle / cam end. Even applying as much force as possible, the switch does not skip the cam to the alternate position. The toggle must be lifted, and is quite heavily spring loaded. As far as I can see, there is no way that such a switch would change position, other than by lifting the toggle, which is, in fact, the way they are designed to work.

Subjects: None

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RAT types vary significantly by aircraft family. The 777 and 787 types (along with most BBD aircraft) are indeed dual hydraulic-electric (lifted from the 2010 FCOM available online):


Other types are different. The A350/A380 do have an electric-only RAT with adequate electric flight controls.

The A320/A330 have a hydraulic-only RAT with a separate hydraulic-driven electrical generator. The 757/767 are similar except the generator is optional.

Some used an electric RAT to drive an electric hydraulic pump.

Be careful when attempting to transfer knowledge from one type to another.

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Last edited by Saab Dastard; 19th June 2025 at 16:45 . Reason: Reference to deleted post removed

Subjects FCOM  Generators/Alternators  Hydraulic Failure (All)  RAT (All)

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Quote:

Originally Posted by Europa01

I\x92ve had a look at the Honeywell spec sheet for TL type switches. They are a common type with many available configurations and are essentially a normal looking snap action switch. The locking feature is an add-on which can be specified. I have to say that from the diagrams, the locking mechanism doesn\x92t look that robust and I\x92d guess that it is subject to wear which was probably the basis of the SAIB. Given that this is a mechanical locking device seeing frequent use possibly with less than full mechanical sympathy it is possible to see how wear would occur making the lock less effective. This does beg the question of whether a check on the mechanism has made it into maintenance routines. ( Note - the locking mechanism appears to be the same for all TL switch types) . Those familiar with the switches - what do you think?
For the avoidance of doubt, the above is a technical observation on the switch type NOT a causation theory for this accident.

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 Condolences  Honeywell  Special Airworthiness Information Bulletin

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Quote:

Originally Posted by LGB

So they only got to around 100' height, half the wing span of a Boeing 787? I think it looks higher than that..

The last report received from ADS-B out is 625 ft but, at that point, the aircraft is still over the runway. The video shows the aircraft continued to climb after passing the departure end.

There is no conflict. Simply a lack of ADS-B data.

Edit - Add the ADS-B data points graphic that I had posted June 17.

Subjects ADSB

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Draw your own conclusions.
Personally, I trust there were no issues.

Subjects: None

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Quote:

Originally Posted by Musician

Draw your own conclusions.
Personally, I trust there were no issues.

Quite.
​​​The 787 is operated throughout the middle East where temperatures far exceed that experienced in this instance.

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Last edited by T28B; 19th June 2025 at 17:15 . Reason: format and spelling assistance

Subjects: None

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Quote:

Originally Posted by StudentInDebt

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

The type of switch being discussed is the specific type reported as being liable to problems. The SAIB is here https://ad.easa.europa.eu/blob/NM-18...SIB_NM-18-33_1 and specifies a part number for the B788 as 4TL837-3D

That's a TL series switch with 4 poles (the "4" in "4TL"), a "type D" lock (meaning locked out of centre position per the Honeywell data sheet - the "D" in "3D." This is a photo of one:


You can find the manufacturer's datasheet here: https://octopart.com/datasheet/4tl83...ywell-25749542

Problems with critical switches aren't new on 787-8s. For instance, in addition to the SAIB above, there's this AD: https://www.federalregister.gov/docu...pany-airplanes

Looking at the photo above, it isn't just wear that's potentially an issue, but foreign object impingement. There don't appear to be gaitors fitted to these switches in the 788, so the locking mechanisms are potentially susceptible to a build-up of material if not kept clean. There are a range of other failure modes possible, whilst the SAIB specifically describes found-in-the-field problems with these switches.

Yes, they're chunky, and very positive when new. That doesn't mean they shouldn't be discussed.

Subjects Air Worthiness Directives  Honeywell  Special Airworthiness Information Bulletin

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Galaxy flyer,
UPS had a triple engine shutdown on A RR Tay engined 727. The crew got one started in the nick of time and were able to land at KORD. I know the crewmemebers.

An old post from 2004,

Subjects Engine Failure (All)  Engine Shutdown

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slf/ppl here - with a respectable amount of experience in software delivery for real-time/embedded/safety critical systems. Software development in this area really is an engineering discipline and bears no resemblance to common practice in other areas. Couple that with the requirements for function duplication/triplication, harness separation et al then IMHO the chances of FADEC etc software errors are effectively zero.


I'm commenting to make that point but also to link the videos and the FR-24 dataset - (below with my deltas for height/time added)



Extract from FR24 csv dataset


As noted in both threads to date everything was normal until it wasn't - the two values for fpm above are subject to FR24 variance of +/- 25' so even these suggest a normal climb at this stage of flight ca 2,000fpm. FR24 Lat/Longs all follow the centre line.


On this data the climb stops at around 70' AGL and electrical failure around 2s later. Again, as noted in the threads, this aligns with when gear up might have been expected. If the climb stopped because of fuel shutoff then 2s for spool down to electrical failure isn't out of the question.


Looking at the two videos.

The CCTV video indicates a total flight time, from rotation, of about 32s, subjectively levelling off ~14s after rotation.

The rooftop video has a flight time ~14s suggesting the video starts ~18s after rotation.


The rooftop video evidences the RAT as deployed from the beginning - meaning it must have been deployed by at least 16s after rotation - which aligns with the ADS-B indicated electrical failure.


If the forward flight recorder really is being sent to the US for recovery then it's reasonable to assume that the rear recorder contains nothing after the electrical failure and they are hoping the forward recorder captured something from the cockpit in the final 16s.


I don't have any experience of flight deck CRM but I don't see how those timings allow problem identification/misidentification and subsequent action - ie it wasn't down to the crew.


However:

The maximum aircraft height in the CCTV video, as judged by wingspan, appears higher than 71' - though it is certainly less than a wingspan height at the beginning of the rooftop video.


I haven't seen, in the threads, any statement of what happens on the flight deck with a total electrical failure - is it a 4s blackout whilst the RAT deploys and systems restart? - or are there batteries that keep something alive?

Subjects ADSB  CCTV  DFDR  Electrical Failure  FADEC  FlightRadar24  RAT (All)  RAT (Deployment)  Relight

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Quote:

Originally Posted by skwdenyer

The type of switch being discussed is the specific type reported as being liable to problems. The SAIB is here https://ad.easa.europa.eu/blob/NM-18...SIB_NM-18-33_1 and specifies a part number for the B788 as 4TL837-3D

That's a TL series switch with 4 poles (the "4" in "4TL"), a "type D" lock (meaning locked out of centre position per the Honeywell data sheet - the "D" in "3D." This is a photo of one:


You can find the manufacturer's datasheet here: https://octopart.com/datasheet/4tl83...ywell-25749542

Problems with critical switches aren't new on 787-8s. For instance, in addition to the SAIB above, there's this AD: https://www.federalregister.gov/docu...pany-airplanes

Looking at the photo above, it isn't just wear that's potentially an issue, but foreign object impingement. There don't appear to be gaitors fitted to these switches in the 788, so the locking mechanisms are potentially susceptible to a build-up of material if not kept clean. There are a range of other failure modes possible, whilst the SAIB specifically describes found-in-the-field problems with these switches.

Yes, they're chunky, and very positive when new. That doesn't mean they shouldn't be discussed.

This switch thing is a nothing burger. If you\x92ve ever operated these switches you\x92d know how they feel. They require a very distinct pull and are most definitely either on or off. There is no impossibly balanced in between position.

Subjects Air Worthiness Directives  Honeywell  Special Airworthiness Information Bulletin

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Quote:

Originally Posted by StudentInDebt

No, it doesn’t “only” happen in these cases!

It is very, very, very close:

Both engines failed: yup, both engines have failed.
Triple hydraulic pressure low: either you've been hit by a SAM/uncontained engine failure causing massive fluid leaks, or both engine driven pumps have failed (likely because the engines have failed) and all four electric pumps have failed (because the engines have failed).
Loss of all electric power to flight instruments both sides: total AC electric loss, and I think battery/static inverter too? Given four generators and four buses, either massive electrical failure (swimming pool in E&E bay) or engines have failed. Note failure of an individual contactor that can tie two buses together should not cause a quad-bus outage.
Loss of all four electric motor pumps: total AC failure, see above.

Subjects Electrical Failure  Engine Failure (All)  Engine Shutdown  Generators/Alternators  Hydraulic Failure (All)

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Quote:

Originally Posted by Someone Somewhere

It is very, very, very close:

Both engines failed: yup, both engines have failed.
Triple hydraulic pressure low: either you've been hit by a SAM/uncontained engine failure causing massive fluid leaks, or both engine driven pumps have failed (likely because the engines have failed) and all four electric pumps have failed (because the engines have failed).
Loss of all electric power to flight instruments both sides: total AC electric loss, and I think battery/static inverter too? Given four generators and four buses, either massive electrical failure (swimming pool in E&E bay) or engines have failed. Note failure of an individual contactor that can tie two buses together should not cause a quad-bus outage.
Loss of all four electric motor pumps: total AC failure, see above.

thanks for posting the conditions, while likely it deployed as a result of a simultaneous loss of both engines, not the only circumstances then.

Subjects Electrical Failure  Engine Failure (All)  Engine Shutdown  Generators/Alternators  Hydraulic Failure (All)

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Quote:

Originally Posted by jdaley

FR24 Lat/Longs all follow the centre line.

More or less.

Subjects FlightRadar24

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EAFR documentation

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Quote:

Originally Posted by xetroV

Do both EAFRs run on emergency power? Could it be possible that only ONE (if any) EAFR unit was recording after the supposed loss of thrust on both engines? If the other one is severely damaged we might as well end up with NO EAFR data from the critical last part of the flight. Perhaps both units are severely damaged? I\x92m not convinced your optimism is entirely warranted.

Both EAFR run on standby power, yes. In addition, the forward EAFR has its own battery backup. However, the number of devices that still send valid data to the EAFR during a power outage is diminished, of course.

The black rubber cap protects a multi-pin connector.

The white cylinder is an underwater location transmitter.

The forward EAFR has its own backup power.

Source: https://www.geaerospace.com/sites/de...rder-3254F.pdf

Subjects EAFR

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Quote:

Originally Posted by EXDAC

In the CSV data set that can be downloaded from that link the first point with altitude data is 1630 ft short of the departure threshold. That point is 575. The highest alt recorded in the data set is 625. All the points with altitude data overlay the departure runway. I do not understand how anyone is using this data set to determine the maximum altitude which was way past the departure end.




Edit to add - I have made no attempt to correct the raw ADS-B altitude data. There is no need to make any correction to see altitude gain.

I posted my first-cut analysis in the earlier thread.
I've had a bit more time to analyse now.
Those ADS-B data points (and particularly the rate of deceleration) are EXACTLY what you would expect to see from a total engine failure at or very shortly after TAKE-OFF
(it implies a 13:1 L/D which must be pretty close for gear down and flaps 5).
It places takeoff at 700m before the runway end @ ~185kt
Based on those, max altitude was c250ft @ 140kt (or the equivalent total energy equivalent), 500m after the end of the runway.
13:1 L/D would also get you groundspeed on impact of 120kt
Do those numbers make sense?

Subjects ADSB  Engine Failure (All)

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