Mitch Cronin Posted October 12, 2007 Share Posted October 12, 2007 ... not how that sounds... Two questions. One on each: 1- I've got an idea in my head that there's some kind of rule about feeding tank to engine during take-off? ...that is... left tank to left engine, right tank to right engine, until ...? flaps up maybe?. I thought there existed a rule of sorts, and I thought all the beasts I'd diddled with would either do so themselves, or would be so configured manually. I learned today that the 777 will, at every opportunity, show me that what I once thought I knew, is frighteningly often wrong.... there apparently aint no auto-anything that'll accomplish that one on this bird, and nobody I heard from knew what I was talking about. Am I inventing that memory, or was it true once, on some airplane, or something? Similar thing with a trick from a memory of something else that may not exist: 2- Igintion on continuous (or whatever an equivalent might be called) during autoland? SOP? Once? CAR? In the past? FAR? Far out?? Link to comment Share on other sites More sharing options...
J.O. Posted October 13, 2007 Share Posted October 13, 2007 Mitch: While I have a few less years in this end of the biz than a wise old elf such as yourself , I don't recall either of those being a regulated item. I suspect they may have been either aircraft specific, a manufacturer's recommendation, or a company SOP. That said, someone will probably correct me shortly. Link to comment Share on other sites More sharing options...
Don Hudson Posted October 13, 2007 Share Posted October 13, 2007 Mitch; The A340 fuel feed is entirely automatic and requires no attention other than the hourly fuel checks for balance, "how-goes-it?" and leaks. Its an extremely sophisticated system. The -500 had fuel system issues I know but the 300's system worked without major issues. "Continuous ignition" isn't a concept I have heard since my time on the B727 and B767 22 years ago. The 320/340 designs offer ignition automatically during any sensed flameout, during anti-ice use on the -500 and if I recall correctly, after slat-extension on approach, (but I think that is no longer the case). In short, the guidance in the AOM is for IGN to be selected if there is standing water on the runway or heave rain or moderat turbulence is expected after takeoff. All other cases are automatically sensed. You will never convince me that the autoflight/autopilot/autothrust/FMGC systems on the B777 are superior to the A340 design but my biases have been and are right up front. Also, I haven't flown the aircraft so there is ignorance at work here, . In the end it matters not because, like the B767 which I did fly for four years, I suspect the B777 is one hell of a fine airplane to fly. Don Link to comment Share on other sites More sharing options...
Mitch Cronin Posted October 13, 2007 Author Share Posted October 13, 2007 Well, these days almost any new trick is just a matter of another processor or two at most, and more probably just some extra software, right? The major differences between Airbus and Boeing really do seem to be in design philosophy... (that's auto-throttle on a Boeing remember. ) This machine will also do all the auto-magic Don... seems like everything you could possibly think of can be pulled up on the displays, and is monitored for something else somewhere. It truly is remarkable how much gee whiz stuff this thing has goin' on in it... but in a very Boeing way, it still manages to maintain some tried and true simplicity. Better than the Bus? Well at least it's got real engines. Thanks guys, for helping me confirm that I was at least right about my horrible memory. Now I apparently invent memories to fill in the blanks... that can't be a good thing. Cheers, Mitch Link to comment Share on other sites More sharing options...
Don Hudson Posted October 13, 2007 Share Posted October 13, 2007 Engines? Whassamatter with hairdryers? Sheesh. See? Told you I was biased. Link to comment Share on other sites More sharing options...
anonymous Posted October 13, 2007 Share Posted October 13, 2007 The engines on the 777 are FADEC which will automatically attempt to restart should the EEC sense a flameout....on older engines like the JT9D which are not FADEC, various systems turn on the ignition, like extending the flaps (for takeoff and landing) and turning on the engine anti-ice...it's an AFM limitation to have ignition on for t/o, landing, and in turbulence Link to comment Share on other sites More sharing options...
anonymous Posted October 13, 2007 Share Posted October 13, 2007 for the 767 with respect to fuel tank to engine configuration again, another AFM limitation "With no center tank fuel use tank-to-engine fuel feed for take-off and landing with all operable main tank boost pumps on and the crossfeed valve(s) closed." Link to comment Share on other sites More sharing options...
Specs Posted October 13, 2007 Share Posted October 13, 2007 I was never invoved in fuel system design certification but from lunchtime conversations I gathered that all fuel systems were generally designed such that fuel feed priority is to default to CTR TK priority. At t/o, All pumps operate but CTR TK pumps run at higher psi and drain first. It's a safety issue (imagine a pipe bursting during t/o). There are also structural and aerodynamic reasons for using CTR TK fuel first. Link to comment Share on other sites More sharing options...
Mitch Cronin Posted October 13, 2007 Author Share Posted October 13, 2007 That's the case with the 777 as well Specs... As with the '67, the center tank pumps put out more pressure, so that tank will empty first... but I had it in my head since the 47 classic that tank to engine would be the config just for take-off. I guess I'd muddied up my notions of procedure and requirement somehow... Glad to hear some confirmation that the procedure once existed. Thanks Anonymous. The autorelight feature in this GE90 is just one of it's cute little tricks... if the EEC senses a rapid decrease in N2, or too low an N2, or too low Ps3 (compressor discharge pressure), it fires both ignitors. But what I was looking for was something that would turn ignition on during approach, or autoland I thought maybe... or something like that, but apparently not. Maybe the autorelight feature makes that unnecessary? The book I've got just says "CON" (the continuous ignition selection) can be selected any time and "the crew will normally select CON ignition during operation in heavy rain, severe turbulence [stay away from that, will ya!], or volcanic ash." [that too!]... but nothing else. There's some real beauty in this bird, but there's the odd thing that's got me scratching my noggin... I'm not sure if some of that's because our course material is too limited and I'm not getting the full picture, or I just can't quite see things the same way the creators did. The alternate gear extension business is a case in point!... But over all.... she seems like a very fine machine! Link to comment Share on other sites More sharing options...
boestar Posted October 13, 2007 Share Posted October 13, 2007 Pretty much every manufaturer does it different. As noted above with the Boeing and Airbus the fuel feeds FROM the CENTER first. In Bombardier aircraft the Wings ALWAYS feed the Engine (Tank To Engine) the center thank feeds the wings. this goes for the CRJ, Global EXpress, Challenger etc. Different philosophies all around. B Link to comment Share on other sites More sharing options...
Innuendo Posted October 13, 2007 Share Posted October 13, 2007 Mitch, don't trust all this new fangled automation. Just do your take off using the tank/s to engine/s that you did the runup and Mag check on Link to comment Share on other sites More sharing options...
RFL Posted October 14, 2007 Share Posted October 14, 2007 Mitch, don't trust all this new fangled automation. Just do your take off using the tank/s to engine/s that you did the runup and Mag check on Before start check: Brakes, Belts & Benzine. The rest is just fluff! Link to comment Share on other sites More sharing options...
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