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(B A) 747-400 question

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(B A) 747-400 question

Old 27th Jun 2022, 20:41
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(B A) 747-400 question

I started another thread regarding crew family cockpit visits & whilst thinking about my next post , half remembered something , so here’s the question.
My 747- 400 cockpit experience was ONLY British Airways’ but I recall that many of them had a plaque / notice , reading ‘This aircraft is ... rated’.
I think it was on the instrument panel , in the centre , but I’m not at all sure- and I think it related to the aircraft max’ speed.
Could someone please explain what it was & what it meant?
Thanks again!
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Old 28th Jun 2022, 05:37
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The placards said, “This aircraft is ‘G’ rated” or “This aircraft is ‘H’ rated” and they referred to the engine thrust rating. We had to check that the FMS engine rating was the same as on the placard. BA had a mixed fleet at the time, and they were worried that an FMS or engine could be re-fitted after repair that was incompatible. Intermix flying with two different ratings was not allowed.

The Rolls Royce RB211-524G had about 56,000 lbs of thrust and the 524H had about 60,000 lbs of thrust at seal level (if memory serves). I believe it was a fairly simple tweak of the EEC plus a pin change for the FMS which decided which rating was available.

From about 2008 all engines on the fleet were de-rated to ‘G’s but the sims were all ‘H’s! Didn’t really make much difference in the grand scheme of things.

Another mod introduced was the ‘Trent Core’, which reduced EGT and Fuel burn. Those engines were 524G/T or 524H/T.

Hope this explains what you were asking about.
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Old 28th Jun 2022, 07:54
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Thanks eckhard , that’s explained it wonderfully!
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Old 28th Jun 2022, 18:07
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Originally Posted by eckhard View Post
The Rolls Royce RB211-524G had about 56,000 lbs of thrust and the 524H had about 60,000 lbs of thrust at seal level (if memory serves). I believe it was a fairly simple tweak of the EEC plus a pin change for the FMS which decided which rating was available.
Just to clarify a bit, the engine rating is listed on the engine data plate - changing the engine rating requires changing the engine data plate and requires the implementation of an engine company service bulletin. There is a 'rating plug' that literally plugs into the EEC (aka FADEC) - the configuration of that plug tells the software what rating to select. The rating plug is attached to the fan case with a lanyard so it will stay with the engine when the EEC gets replaced (a fairly common maintenance practice).
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Old 28th Jun 2022, 19:58
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Thanks td’
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Old 30th Jun 2022, 13:47
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Thanks tdracer and you’re welcome Flugzeug A.

Another reason for the placard was that at that time we used paper manuals for take-off and landing performance. The manuals were also titled with ‘524G’ or ‘524H’ and to avoid mistakes, we had to check that the manual being used matched the placard in the cockpit.
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Old 30th Jun 2022, 20:46
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Ta once more eckhard.
I couldn’t find anything on the ‘net & was starting to think I’d imagined it.
All fascinating stuff to the visitor on the jump seat : to you & the other crews , many thanks for having me.
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Old 1st Jul 2022, 15:03
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Originally Posted by Flugzeug A View Post
I started another thread regarding crew family cockpit visits & whilst thinking about my next post , half remembered something , so here’s the question.
My 747- 400 cockpit experience was ONLY British Airways’ but I recall that many of them had a plaque / notice , reading ‘This aircraft is ... rated’.
I think it was on the instrument panel , in the centre , but I’m not at all sure- and I think it related to the aircraft max’ speed.
Could someone please explain what it was & what it meant?
Thanks again!
Could it be related to weight. Various aircraft can have a placard that can be removed, flipped over, and secured again to adjust the certified max allowable takeoff weight for landing fee purposes. That being said, it wasn't located on the instrument panel.
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