grumpyoldgeek
June 15, 2025, 03:05:00 GMT
permalink Post: 11902051

Quote:

Originally Posted by Xeptu

It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight)

I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight.

Subjects V1

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grumpyoldgeek
June 15, 2025, 22:49:00 GMT
permalink Post: 11902876

RAT and best glide

Firstly. I find all the speculation about hearing the RAT suspect. Not that I doubt observers heard something sounding like a RAT, but that I question the fidelity of the low bit rate and bit depth of the audio to reproduce the difference between the sound of a deployed or non-deployed RAT. The audio sounds quite distorted and I have zero confidence that anyone could accurately tell. Secondly, is the speculation about best glide performance. Any private pilot knows that best glide does not exist until the pilot pitches the nose down and establishes it. As far as I can see, there is no time nor visible indication that the nose pitched down. What I see is the aircraft mushing down to the ground with the nose high and just short of a stall.

Subjects RAT (All)

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grumpyoldgeek
June 16, 2025, 01:51:00 GMT
permalink Post: 11903014

Quote:

Originally Posted by boeing_eng

I've ground tested countless RAT's on 757/767's over many years....

Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard

Not trying to be a smart ass, but how do you "ground test" a RAT?

Subjects RAT (All) RAT (Deployment)

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grumpyoldgeek
June 16, 2025, 01:51:00 GMT
permalink Post: 11903733

Quote:

Originally Posted by boeing_eng

Not trying to be a smart ass, but how do you "ground test" a RAT?

Subjects RAT (All) RAT (Deployment)

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grumpyoldgeek
June 19, 2025, 19:47:00 GMT
permalink Post: 11906262

Has it been determined from the wreckage that the RAT was deployed at the time of impact?

Subjects RAT (All) RAT (Deployment)

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grumpyoldgeek
June 20, 2025, 00:59:00 GMT
permalink Post: 11906498

Quote:

Originally Posted by MatthiasC172

Can someone help me with the calculations on how far from the point of our last ADS-B readout we can expect the stricken jet to fly/glide?

I am assuming the take off mass around 190-200 tons with 50 tons of fuel. For the glide phase this is of no importance, however.

Data on the Internet puts the glide ratio of a 789 around 18-21:1. Gear and flaps/slats out should have a significant negative effect. Does anyone have a good take how much? Minus 40%?

From the available data we can infer the plane never was higher than 200\x92 AAL, maybe even 100\x92. If I understood the online sources correctly, the point of impact was only about 20\x92 lower than the average runway level.

If I am not mistaken the distance from the last ADS-B point to the impact site is about 2 km as per Reuters and the Guardian. That would put it at 6,500\x92.

I just can\x92t get these numbers over each other without the aircraft producing thrust. Please help me correcting the numbers.

Best glide performance doesn't start until the pilot pitches the nose down and establishes best glide. As near as I can see, the nose never pitches down.

Subjects ADSB

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grumpyoldgeek
June 26, 2025, 22:58:00 GMT
permalink Post: 11911531

Quote:

Originally Posted by D Bru

Thx, this indicates at least two issues:

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

I have to disagree with point 1. They did not give a reason for using the front unit and I don't see why you would assume one.

Subjects CVR EAFR RIPS

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grumpyoldgeek
July 13, 2025, 02:51:00 GMT
permalink Post: 11920984

Quote:

Originally Posted by Alty7x7

Would not expect an FDR dedicated pole. They might pull the FCS position from the FADEC, since what really matters is what the FADEC receives as a command. I would expect two poles dedicated to the two circuits, one routed to each FADEC channel, and the others to the non-FADEC-reset-command functions.

I'm guessing they use a separate set of contacts to electrically isolate the FADEC wiring from the flight recorder wiring. Which would seem like a good idea.

Subjects DFDR FADEC FDR Fuel (All) Fuel Cutoff Switches

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grumpyoldgeek
July 15, 2025, 00:56:00 GMT
permalink Post: 11922584

Quote:

Originally Posted by barrymung

I don't buy the idea that both switches failed at virtually the same time.

I don't buy the idea that even one switch failed.

Subjects: None

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grumpyoldgeek June 15, 2025, 03:05:00 GMT permalink Post: 11902051	Quote: Originally Posted by Xeptu It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight) I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight. Subjects V1 Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 15, 2025, 22:49:00 GMT permalink Post: 11902876	RAT and best glide Firstly. I find all the speculation about hearing the RAT suspect. Not that I doubt observers heard something sounding like a RAT, but that I question the fidelity of the low bit rate and bit depth of the audio to reproduce the difference between the sound of a deployed or non-deployed RAT. The audio sounds quite distorted and I have zero confidence that anyone could accurately tell. Secondly, is the speculation about best glide performance. Any private pilot knows that best glide does not exist until the pilot pitches the nose down and establishes it. As far as I can see, there is no time nor visible indication that the nose pitched down. What I see is the aircraft mushing down to the ground with the nose high and just short of a stall. Subjects RAT (All) Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 16, 2025, 01:51:00 GMT permalink Post: 11903014	Quote: Originally Posted by boeing_eng I've ground tested countless RAT's on 757/767's over many years.... Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard Not trying to be a smart ass, but how do you "ground test" a RAT? Subjects RAT (All) RAT (Deployment) Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 16, 2025, 01:51:00 GMT permalink Post: 11903733	Quote: Originally Posted by boeing_eng I've ground tested countless RAT's on 757/767's over many years.... Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard Not trying to be a smart ass, but how do you "ground test" a RAT? Subjects RAT (All) RAT (Deployment) Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 19, 2025, 19:47:00 GMT permalink Post: 11906262	Has it been determined from the wreckage that the RAT was deployed at the time of impact? Subjects RAT (All) RAT (Deployment) Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 20, 2025, 00:59:00 GMT permalink Post: 11906498	Quote: Originally Posted by MatthiasC172 Can someone help me with the calculations on how far from the point of our last ADS-B readout we can expect the stricken jet to fly/glide? I am assuming the take off mass around 190-200 tons with 50 tons of fuel. For the glide phase this is of no importance, however. Data on the Internet puts the glide ratio of a 789 around 18-21:1. Gear and flaps/slats out should have a significant negative effect. Does anyone have a good take how much? Minus 40%? From the available data we can infer the plane never was higher than 200\x92 AAL, maybe even 100\x92. If I understood the online sources correctly, the point of impact was only about 20\x92 lower than the average runway level. If I am not mistaken the distance from the last ADS-B point to the impact site is about 2 km as per Reuters and the Guardian. That would put it at 6,500\x92. I just can\x92t get these numbers over each other without the aircraft producing thrust. Please help me correcting the numbers. Best glide performance doesn't start until the pilot pitches the nose down and establishes best glide. As near as I can see, the nose never pitches down. Subjects ADSB Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek June 26, 2025, 22:58:00 GMT permalink Post: 11911531	Quote: Originally Posted by D Bru Thx, this indicates at least two issues: 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 I have to disagree with point 1. They did not give a reason for using the front unit and I don't see why you would assume one. Subjects CVR EAFR RIPS Links are to this post in the relevant subject page so that this post can be seen in context. The thread is closed so there are no user likes are available and no reply is possible.
grumpyoldgeek July 13, 2025, 02:51:00 GMT permalink Post: 11920984	Quote: Originally Posted by Alty7x7 Would not expect an FDR dedicated pole. They might pull the FCS position from the FADEC, since what really matters is what the FADEC receives as a command. I would expect two poles dedicated to the two circuits, one routed to each FADEC channel, and the others to the non-FADEC-reset-command functions. I'm guessing they use a separate set of contacts to electrically isolate the FADEC wiring from the flight recorder wiring. Which would seem like a good idea. Subjects DFDR FADEC FDR Fuel (All) Fuel Cutoff Switches Links are to this post in the relevant subject page so that this post can be seen in context. No recorded likes for this post (could be before pprune supported 'likes'). Reply to this quoting this original post. You need to be logged in. Not available on closed threads.
grumpyoldgeek July 15, 2025, 00:56:00 GMT permalink Post: 11922584	Quote: Originally Posted by barrymung I don't buy the idea that both switches failed at virtually the same time. I don't buy the idea that even one switch failed. Subjects: None 10 recorded likes for this post. Reply to this quoting this original post. You need to be logged in. Not available on closed threads.

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