Easy for some... but it certainly gave me a headache, Laurent :-)I guess you did use the expression "PIC". As for the real aircraft... things get a little more complicated....1. Bank Limit Selector is only active in HDG SEL mode?: True, they say.2. T/O pitch mode can not be engaged in CMD mode?: True and False... It depends on aircraft option pin programming, FCC type, etc.3. Center A/P is powered by left AC bus?: Yes and (maybe) no. The Center FCC is powered by the Center Bus which is powered by the Left Bus in most phases of flight. During a normal Autoland (Land 3), Bus Isolation takes place. The Center Bus is then powered by the Standby Bus/Static Inverter. However, normally the Standby Bus is powered by the Left Bus anyway, so the Center FCC is still powered by the Left Bus.Now, what happens if the Left Generator fails during Land 3 and the APU is not running? (This is the part where I get lost) Is Bus Isolation cancelled? Does everything run off the Right Bus? Or does Bus Isolation remain, leaving the Center Bus to run off the Battery/Static Inverter? (Is Bus Isolation cancellation "height dependent"?)Of course, the expression "A/P" could mean more than just the FCC (Flight Control Computer). Things could get really complicated if we started looking at servo's, indication, data inputs, etc.4. FLCH is the fastest mode to change flight level in cruise?: Yes, no, maybe (Interesting question). How many flight levels are you traversing? Is the aircraft fitted with "intelligent FLCH"? (If so and if the altitude change is not too large (say 1000'), the aircraft might not try to go like a bat out of hell to the next altitude. With the old style FLCH, the aircraft would try to achieve the new altitude within a certain time period, so may use full thrust to get to the new altitude. You would also have to ask if the pilot was messing around with the MCP speed setting during FLCH ops).If V/S was chosen, and the pilot dialled in, say, 5000fpm and the altitude change was not so large, then perhaps the aircraft wouldn't stall by the time it reached the new altitude.... so this would definitely be the fastest way to change flight levels. If VNAV was selected for the flight level change the answer would depend on who you ask. Some say that for small altitude changes, VNAV doesn't use full climb thrust to get to the next altitude. Others say that full climb thrust is always given.If the aircraft is cruising at a low altitude in VNAV, I assume it will be flying to an airspeed, rather than a mach number. If VNAV is used to climb to a high altitude/FL, the aircraft will automatically switch to a fixed mach number. FLCH, I believe, would stick to the same airspeed during the climb (how would this affect climb rates?)5. Right AC bus failure does not prevent you from engaging AUTOLAND?: I'll go for true on this one, but I'll probably live to regret it :-)6. VNAV SPD is always a pitch-to-speed mode?: Yes... I've been told.Hope your next one is easier than this, Laurent :-lolCheers.Ian.

DO NOT READ ON IF YOU HAVENT DONE THE POLL YET!!!Ian, with to my reference, the AOM of an aircraft, i think you know(yes the 747-441) i concluded, that n

:-hmmm = as I started thinking on this poll :-newburn = what my head did while I pondered this poll *:-* = what I looked like after making my selection :'( & :-newbie = how I feel about my PIC knowledge nowI wound up guessing (and I'm not saying what I chose until I know the answer) ;-)I'm thinking I put waaayyy too much thought into this poll.

Hi Ian,You see I know how to get the fox out of his earth Ha Ha Ha :-wink2Regards,Laurent

oh Laurent, just like every single belgian, evil in heart and kidneys (or in dutch, vals in hart en nieren ;-))

"Now, what happens if the Left Generator fails during Land 3 and the APU is not running? (This is the part where I get lost) Is Bus Isolation cancelled? Does everything run off the Right Bus? Or does Bus Isolation remain, leaving the Center Bus to run off the Battery/Static Inverter? (Is Bus Isolation cancellation "height dependent"?)"Here's what I found in the Boeing Maintenance Manual....The (Elec) Bus Isolation command is given when ...1. The approach (APP) mode is selected2. The A/P is single channel engaged, multi channel armed (offline channels are automatically armed by the FCC's(A/P computers) when APP is selected) in the CMD mode3.Autoland Status Annunciator (ASA) is NOT displaying "NO LAND 3".According to the BMM, a "NO LAND 3" status exists if a single FCC (A/P computer), A/P servo, or "outer loop" sensor failure occurs. This "NO LAND 3" display is inhibited below 200ft unless already displayed, or no FCC is in the CMD mode. I'm thinking that if the Left Generator failed below 200', NO LAND 3 would not be annunciated... therefore, Bus Isolation would remain. However, it is still not clear (to me) what would power the Center Bus in this case. It will be powered by the Static Inverter, but what would power the Static Inverter in this scenario, I'm not sure. It could be the battery or it could still be the Left AC Bus (considering the fact that if the generator died, the L & R Bus Ties would close... and the Right Bus would be powering the Left Bus).Here's where I get lost again... If the Left Gen failed below 1500', but above 200', would you get a NO LAND 3 message? If so, why? The BTB's would close and allow the Right Bus to power the Left Bus, so you would get power to the L FCC, the L A/P servos and the outer loop sensors. This still appears to meets the requirements for not displaying a NO LAND 3 message (???)."Of course, the expression "A/P" could mean more than just the FCC (A/P or Flight Control Computer). Things could get really complicated if we started looking at servo's, indication, data inputs, etc."The C A/P servo is driven by the Left Main DC Bus... until Bus Isolation occurs. In which case, it appears to be driven by the 28V Hot Battery Bus. What powers the Hot Battery Bus during A/L is a mystery to me at the moment.Does anyone out there really know how this airplane works??? :-)Cheers.Ian.http://www.ozemail.com.au/~iriddell/767/Electrics.gif

I'm desperately hoping more than one fox will emerge, Laurent... (Hopefully one of them will be Eric.... I think we need him at the moment :-)).Cheers.Ian "still confused as ever" R.

Of course, the answers come (a little more) easily when you find the right books.... :-)Just found what I was looking for in a proper pilot's manual (re what powers the Center AC Bus during gen failures).If a generator fails above 200' during Autoland, the bus ties will close and "NO LAND 3" will appear on the ASA.The C A/P will be powered by the L Bus.However, if a generator fails below 200', the R/L bus ties will remain open and the 2 remaining A/P's will be powered by their respective operating busses. This means that if the Left Generator failed, the Left Bus will be dead... and the only way to power the Center A/P will be via the Main Battery and Stby Inverter. Not sure if the "NO LAND 3" on the ASA will appear in this situation.Anyway, this means that the statement in Laurent's Poll, "3. Center A/P is powered by left AC bus", is not _always_ true.I'm still working on "5. A Right AC bus failure does not prevent you from engaging AUTOLAND". I may need a bigger book for that one ;-)So, so far, I have two "trues", two "mostly trues", one "I don't know yet, but the truth is out there" and one "it depends on who you ask and how irresponsibly you fly the airplane" :-) Cheers.Ian.

"Ian, with to my reference, the AOM of an aircraft, i think you know(yes the 747-441) i concluded, that n

Fine Ian !You know your comments are building my technical "bible" for the 767. These kind of informations are always difficult to find in the pilot's manuals.N.B. But for the poll, there is no doubt the answer should be the only one which is blatantly wrong !Laurent_____________________________767PIC Panel co-designer

thanks ian, now the AOM may appear to be big, but the size of the pages makes it all worth it ;-)and also there are heaps of informations about revisions to the aircraft, guess for me that's "i'll pass this section" lecture untill FS can actually come up with a decent maintainance manager, and no FSmaintainance does not simulate what i want...Cheers