777~200er fuel pages

[Flamin_Squirrel 71]

Many years ago, in the late 80's, I flew a display at Fairford. Afterwards we had to stand on the line and answer questions. I had one gentleman who, honestly, knew far more about my aircraft, where and when it was build, the engines, lift, thrust, weapons etc. etc. etc. What he didn't know was how to fly it and fight it. :-D

 

Nice! What aircraft did you demo?

[GregL 26]

Nothing glamorous I'm afraid, it was back in my early rotary days, a Sea King Mk V.

 

Great machine vastly underestimated.

[Flamin_Squirrel 71]

Eh, more glamorous than anything I have/will get my mitts on :ph34r:

[kevinh 409]

The simple fact is that I use these aircraft every week and I'm not in the slightest bit fussed if I have a GE or a RR. As I'm not an engineer I am not particularly bothered exactly how specific sensors, knobs, wheels and widgets work in the engine either. I know how to use them. I have enough to do with managing the flight, passengers, destination and ATC not to get bogged down in trivia hence I look for a simplistic approach.

That's perfectly fine, but in amongst those general observations you made some definitive statements which were not generally correct. You can't expect that not to be challenged just because you are a pilot. Not getting bogged down by trivia should not prevent being factual.

[GregL 26]

That's perfectly fine, but in amongst those general observations you made some definitive statements which were not generally correct. You can't expect that not to be challenged just because you are a pilot. Not getting bogged down by trivia should not prevent being factual.

I was dealing deliberately in generics, you supplied the limits that you put onto your interpretation of what was said. There were no definitive if you look, you supplied them.

 

As far as I'm concerned this conversation is over. Back to the thread.

[777simmer 117]

Also, it is quite difficult to cater for everyone with discussion like this.

 

Some have indepth knowledge of the subject or are ingeneers, etc but others are not.

 

My girlfriend for instance thought that the new Album of Mariah Carey was coming out when I mentioned F=m.a to here ;-)

 

Of coure when you start of easy, so everybody can follow and benefit, you are naturally going to end up with inaccuracys as the discussion goes deeper and grows more detailed.

[777simmer 117]

ps, had to look up trivia.

 

Now I know why that game is called trivial persuit ;-)

[kevinh 409]

I was dealing deliberately in generics, you supplied the limits that you put onto your interpretation of what was said. There were no definitive if you look, you supplied them.

 

As far as I'm concerned this conversation is over. Back to the thread.

I'm sorry Greg, but I've re-read the thread and I can't agree with that summary. The idea that 100% N1 was maximum thrust was first mentioned by 777simmer. cva1077 questioned that and I replied suppporting their view with a specific example. You commented on cva1077's reply to me in a way which I felt only confused the issue, so I responded to that post.

 

You began one paragraph by saying "N1 100% may be exceeded for specified periods but specific exceedences must be recorded for engineering inspection." The first part of that sentence is specific: 100% N1 is a value that may be exceeded for a specified time. That implies it is a limit. The second part then says that such exceedances have to be recorded. You may have meant the sentence to read differently, but that is how I read it at the time. On reflection, it could be interpreted as meaning that above 100% N1 there is a limit that must be respected but how does such an obvious statement add anything of value to the discussion?

 

In the same post you mentioned three very different ideas of what 100% N1 represents. First that 100% was the nominal maximum for structural and wear reasons (which is a reasonable definition). Then you said that 100% was determined by the manufacturer for cruise economy. Then you suggested 100% N1 would be the governed max continuous limit for safety. Three different and contradictory interpretations in one post. The last one quite contrary to what you, as a pilot, would be aware of. Engines with FADEC/EEC controllers are indeed governed to remain within operating limits, but that will rarely correspond to 100% N1, so that isn't generally true.

[GregL 26]

You began one paragraph by saying "N1 100% may be exceeded for specified periods but specific exceedences must be recorded for engineering inspection." The first part of that sentence is specific: 100% N1 is a value that may be exceeded for a specified time. That implies it is a limit. The second part then says that such exceedances have to be recorded. You may have meant the sentence to read differently, but that is how I read it at the time. On reflection, it could be interpreted as meaning that above 100% N1 there is a limit that must be respected but how does such an obvious statement add anything of value to the discussion?

Grief.

 

The example was 'made up' to demonstrate a point. The example does not adhere to any known engine with any 'real world' application it is there merely to prove a point that limitations may be exceeded in the real world but must be checked as a point of safety or may carry lifex penalties.

 

I could have stated 100% bananas or 110% bananas if I wished, it is there for theoretical exercise to carry the point that past a specific limit engineering checks are required.

 

Limits are set by engineers and manufacturers for a whole variety of reasons. Three of the above are perfectly valid ones. The military have a different usage profile to civilian aviation and the engines will be manufactured and limited accordingly.

 

Not all engines are governed within safety limits by FADEC. Have a look at large helicopters where, in the event of engine failure the FADEC/EEC/Hydro-mechanical governor (if fitted) will revert to emergency mode to enable the full max power usage of the remaining engine and will govern at max transient power for up to 5 minutes in some cases after which the engine is rejected.

 

In other aircraft the gas turbine doesn't have FADEC or EEC, one of mine had Teleflex and bodenflex cables to the engine throttle quadrant of a 1500shp gas turbine. Over throttling could cause tripping of the overspeed governor and was, thus, frowned upon.

 

So whilst different they are not contradictory just taken from a wide spectrum of operational requirements.

 

I think you were reading a little too literally and I failed to include that the numbers were purely there for example. Potentially I could have couched it a little better.

[cva1077 68]

OK Guys, I think that's enough arguing for now. Why don't we all just leave it and accept what the others had to contribute to the discussion?

[momtchil 32]

Its time to let the argument go.

 

OK Guys, I think that's enough arguing for now. Why don't we all just leave it and accept what the others had to contribute to the discussion?

 

Yes, please lets do that - We couldn't have said it better ourselves!

[martybuzz 2]

...and people wonder why Tech Crew Members don't bother commenting in forums.  Thank you Greg and Rob for trying to share flying knowledge to the masses. 

[777simmer 117]

You are welcome Martin :-)

 

I post because I like to help others (not to show off!) .

And I will do so untill ofcourse I dont like it anymore or until I have the feeling my posts are not wanted anymore.

 

So posts like yours are highly appreciated, thx.