I really love your videos for the technical info, and the ability to see "behind" the things that normally are shown in the multitude of pilots' videos (which are, of course also great). I really appreciate this additional perspective. Thanks for sharing, and please keep the videos coming :)
Hello Dennis, 1)You said that APU must be running for the next flight, because the right Drive Generator is disconnected. Does it mean, that the aircraft has to fly on lower altitudes? I am asking because the APU can only be operated to a certain max altitude. 2)That also would mean higher fuel consumption, right? Especially with APU running and "possible" lower cruising altitude, back to Doha. 3)How does the crew know how much fuel they have to take more? That is bad for the new flightdeck crew that has to deal with these problems from the beginning of the flight. 4)Did you check the right Drive Generator visually? 5)How much time does it take to reactivate the Drive Gen on a 777-300ER? 6)Is it up to the airline if they want to get the aircraft repaired or want to fly with minimum equipment? I know that with this solution it is less expansive for the airline, because otherwise the flight would get canceled and they need to send a replacement aircraft. 7)But what is if the APU or the left GEN would fail, too? Could the aircraft still continue the flight or would that be an emergency case? 8) Because it is a trans atkantic flight, are there any other regulations to be considered regarding MEL and generator faults? 9) Regarding the center isolation valve, could humidity within the valve be a reason why it didnt work? Thanks and I hope you can find time to answer these questions in your lunch break😄
Hello there, let me see if I can answer you questions. In the B777 the use of APU in electrical mode only has no altitude restrictions. If used for providing bleed air max altitude is 22000ft ( that’s emergency only ) you can’t dispatch aircraft with two bleed systems INOP. Fuel consumption at altitude is about 90kg/hr on ground that is about 240kg/hr. I suppose that has been checked during the certification process of the aircraft. So it’s no a big deal, they will need to take about 1400 kg extra for the APU fuel burn. So it is possible cargo or passengers need to be of loaded if aircraft is operating at its max takeoff weight. It is very simple to reconnect and IDG again, you will have to open the engine, and on the IDG is a ring you pull to reconnect the axle to the gearbox again. Only testing will take up a lot of time, aircraft need to be cleared and engine need to be run. Aircraft will take a delay for that and most likely the outcome will be that the IDG is inoperative. Replacement of and IDG is about 4 hours work. So APU is used during the flight as a redundancy, one generator plus the backup generator can feed the whole aircraft with electricity. Also APU can feed the whole aircraft. Aircraft will need to stay 180 minutes from a suitable airport. So if the aircraft would have for example 207 min ETOPS it will be down graded to 180, this aircraft was 180 ETOPS so no extra restrictions. And no other regulations are applicable. Hope it clears it up. And regarding the isolation valve, don’t think humidity is the problem (air going though the bleed air lines is about 200 C) but the position RVDT’s (rotary variable differential transformer) wear out of valve internal components wear / clog up / corrode etc. It can have many causes. Valve was working so my guess is that the RVDT was causing the problem, valve was open but system saw it failed closed.
@@dennisvijverbergbrakesrele6098 Thank you very much. So as long the APU bleed valve stays off, there is no problem with the cruise altitude. It would be very cool to see a long video about the onboard maintenance system and AIMS, AMMA, Tools ect.
I think it is there to do, so that when pilots do there scan of the panel with the checklist, if when list states “turn on” they see it’s INOP. It’s just my take on it, maybe someone has more insight into it. But procedures often ask us to mark system INOP with a placard.
I really love your videos for the technical info, and the ability to see "behind" the things that normally are shown in the multitude of pilots' videos (which are, of course also great). I really appreciate this additional perspective. Thanks for sharing, and please keep the videos coming :)
Thanks, will be keeping it going with all kinds of behind the scenes videos.
Hello Dennis,
1)You said that APU must be running for the next flight, because the right Drive Generator is disconnected.
Does it mean, that the aircraft has to fly on lower altitudes?
I am asking because the APU can only be operated to a certain max altitude.
2)That also would mean higher fuel consumption, right?
Especially with APU running and "possible" lower cruising altitude, back to Doha.
3)How does the crew know how much fuel they have to take more?
That is bad for the new flightdeck crew that has to deal with these problems from the beginning of the flight.
4)Did you check the right Drive Generator visually?
5)How much time does it take to reactivate the Drive Gen on a 777-300ER?
6)Is it up to the airline if they want to get the aircraft repaired or want to fly with minimum equipment?
I know that with this solution it is less expansive for the airline, because otherwise the flight would get canceled and they need to send a replacement aircraft.
7)But what is if the APU or the left GEN would fail, too?
Could the aircraft still continue the flight or would that be an emergency case?
8) Because it is a trans atkantic flight, are there any other regulations to be considered regarding MEL and generator faults?
9)
Regarding the center isolation valve, could humidity within the valve be a reason why it didnt work?
Thanks and I hope you can find time to answer these questions in your lunch break😄
Hello there, let me see if I can answer you questions.
In the B777 the use of APU in electrical mode only has no altitude restrictions. If used for providing bleed air max altitude is 22000ft ( that’s emergency only ) you can’t dispatch aircraft with two bleed systems INOP.
Fuel consumption at altitude is about 90kg/hr on ground that is about 240kg/hr. I suppose that has been checked during the certification process of the aircraft.
So it’s no a big deal, they will need to take about 1400 kg extra for the APU fuel burn. So it is possible cargo or passengers need to be of loaded if aircraft is operating at its max takeoff weight.
It is very simple to reconnect and IDG again, you will have to open the engine, and on the IDG is a ring you pull to reconnect the axle to the gearbox again. Only testing will take up a lot of time, aircraft need to be cleared and engine need to be run. Aircraft will take a delay for that and most likely the outcome will be that the IDG is inoperative.
Replacement of and IDG is about 4 hours work.
So APU is used during the flight as a redundancy, one generator plus the backup generator can feed the whole aircraft with electricity. Also APU can feed the whole aircraft.
Aircraft will need to stay 180 minutes from a suitable airport. So if the aircraft would have for example 207 min ETOPS it will be down graded to 180, this aircraft was 180 ETOPS so no extra restrictions. And no other regulations are applicable.
Hope it clears it up.
And regarding the isolation valve, don’t think humidity is the problem (air going though the bleed air lines is about 200 C) but the position RVDT’s (rotary variable differential transformer) wear out of valve internal components wear / clog up / corrode etc. It can have many causes.
Valve was working so my guess is that the RVDT was causing the problem, valve was open but system saw it failed closed.
@@dennisvijverbergbrakesrele6098
Thank you very much.
So as long the APU bleed valve stays off, there is no problem with the cruise altitude.
It would be very cool to see a long video about the onboard maintenance system and AIMS, AMMA, Tools ect.
This was really interesting indeed, keep them coming.
an entire generator under MEL is wild. boeing move.
@@asilva_media can be done as long as APU is operational.
Hi Dennis, very informative and interesting, keep up the good work; it's appreciated!
Thanks, will do!
thank you for sharing this
My pleasure
Hi Dennis pls any video to dispatch B777 with wing or ENG anti ice valve inop.thanks
Will do if occurs.
Is it needed to place an INOP sticker on the R GEN pushbutton?
I think it is there to do, so that when pilots do there scan of the panel with the checklist, if when list states “turn on” they see it’s INOP.
It’s just my take on it, maybe someone has more insight into it. But procedures often ask us to mark system INOP with a placard.
@@dennisvijverbergbrakesrele6098 Thanks for the info! I'm used to Airbus procedures from when I studied Avionics. But Boeing is quite unknown for me.
Any fault history on the isolation valve?
No, no previous write ups
🎉🎉🎉
They understand all what you say? 😅😅🤔
Crew was briefed by Maintenance Control so they were aware of what needed to be done.
Sounds like they didn't train for this in the sim or even checked the QRH.
Promo'SM