Hi, as I've been lucky enough to get a great deal of jumpseat-rides the last few years, I've noticed one thing in particular when the AC source is changed, that I miss from the NGX. Each time in the real thing I've seen the AC source's been changed (GPU - APU gen - Eng gen), a loud mechanical/electical "click" can be heard, and all displays and screens (and ind/warn lights? Been a while since I was last out flying as of this writing) flimmer or blink for half a second at the same time, as the system inure with the change of source. In the NGX however, you see no visual or audiable change or event, except of course the corresponding indicator lights. Does anyone know if this is a miss or deliberate? Will it be included later? Does the newer (real) NG's still have this feature or not? Thanks

Yeah, no, I partially agree. However, when up on the flight deck in the monitor-based cockpit that is the NG, I find it a nice reminder that this is a complex piece of machinery that is still very mechanic. Also, it's a rather noticable event, when everything you see sudenly blink and you hear that sound

Are you sure you are talking about the NG's? Digital electrical controls and a change of the locations of the big AC solenoids have (from what I understand) all but eliminated the characteristic 'clikity clunk kerplunk' sound from tge NG's.

I remember that being mentioned somewhere - the clicking is not audible on NGs.

Were these jumpseats rides on NGs or Classics (-300 to -500)? I remember reading that this is a specific difference between the NGs and the Classics... I don't remember the source though. In fact, this was one of the first things I wondered about myself when I got the NG (since I was used to, and quite liked, the "clunk" in the 737 PIC). If anyone has a definite source on this, I too would be very interested!As a side note, I remember from airliner flights many years ago that the cabin lights used to flicker just after engine start. At the time, I didn't understand what it was -- later, I realized that it must have been the switch from the APU generator to the engine generator. Of course that doesn't happen any more on the more modern jets...---Martin Boehme

Are you sure you are talking about the NG's? Digital electrical controls and a change of the locations of the big AC solenoids have (from what I understand) all but eliminated the characteristic 'clikity clunk kerplunk' sound from tge NG's.

Well, talking 'bout "modern" planes, the 'buses do that for sure... Quite scary in fact.

I'm 99,5% this was the case on SAS' NGs, as I remember big screens flickering. However, most of those planes have become rather old, so it might have been improved with the newer ones, I don't know.

Generators "pop" is not heard in NG.

Well, talking 'bout "modern" planes, the 'buses do that for sure... Quite scary in fact.

Meh, it ain't to scary for me...as long as the power is restored!

Meh, it ain't to scary for me...as long as the power is restored!

,True again... thought it was scary the first time I experienced it though! Although that was only after landing, so...

Main bus tie breakers have different positions between classic and NG planes.The classic have 2 behind circuit breaker panel P6 (the APU power breakers), and the other 4 are just below the floor of the cockpit, the access is thrugh an access panel in the nose gear wheel well. This make the "pop" louder as it starts from a very little distance and with only one or 2 walls separating the breaker to the cabin.On the NG there are Main boxes containing power devices, it is the modern "filosophy" on how to do.These boxes are in the electronic compartment, just forward of the fwd cargo. And the part number is also different.So tere are a lot of difference in how it sounds, if you are able to hear.

Would it still blink?

The principle is the same, position is different.On the NG, as for the entire 737 series there is no parallel connection of sources, never. Each source powers its own side normally, APU and ground power are connected to both sides by BPCU.And the last selected source exclude the other first, then engage the new one. (milliseconds)Other planes to eliminate glitches sometime allows 2 sources to be online on the same bus (on most of these planes this is for few time, just to allow a safe passage from one source to another), this means that voltage and frequency must be adjusted to match the other one.