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777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 2:18 am
by Max Q
Singapore had / has ? some 777ER models
which they deliberately derated for regional operations


I believe this was done by a paperwork reduction of maximum take off and other weights and maximum engine thrust was reduced and limited with electronic adjustment



This gave SIA a much lighter triple that burned less fuel and paid less in landing fees, although it didn’t have the performance of a regular ER it was more than adequate for regional flights


Not the most efficient solution to the mission, later it was covered by the A333
and now the 787-10 is starting to fill that
niche


So how did these ‘derated’ triples compare in weight, engine thrust and performance to the ‘original’ lightweight 777A models operated by UA / BA / CX ?

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 5:59 am
by strfyr51
Actually? OK as long as no fuel was in the center tank of the ER version

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 10:13 am
by VSMUT
Max Q wrote:
This gave SIA a much lighter triple that burned less fuel


Are you sure? The engine were the same, so for a similar payload and fuel on board, fuel consumption would likely have been the exact same.

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 10:44 am
by BravoOne
Their Operating Empty Weight probably did not change much other the revised seating and galley arrangements. Mostly a function of paperwork. The derated engines are most likely a function of the fuel control / computer logic, but have no weight implications.

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 12:18 pm
by Max Q
Maximum take off weight was reduced significantly, albeit ‘artificially’


Operating at similar weights as an ER would not change the burn but as the aircraft generally operated at much lighter weights fuel burn should improve

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 1:01 pm
by BravoOne
Operated a 767-200ER that had AFM reductions in MTOGW. When we wanted to revise it upwards to it's original delivered weights, Boeing wanted a significant charge for this paper mod. I think we did it with a paper STC and saved probably 50K.

Re: 777A compared to ‘derated ER’

Posted: Wed Nov 21, 2018 2:08 pm
by VSMUT
Max Q wrote:
Maximum take off weight was reduced significantly, albeit ‘artificially’


Operating at similar weights as an ER would not change the burn but as the aircraft generally operated at much lighter weights fuel burn should improve


If you operated an ER on the same routes with the same payload, the weight and fuel burn would be the same. You don't take more fuel just because you have a higher MTOM.

Re: 777A compared to ‘derated ER’

Posted: Thu Nov 22, 2018 1:45 am
by Max Q
VSMUT wrote:
Max Q wrote:
Maximum take off weight was reduced significantly, albeit ‘artificially’


Operating at similar weights as an ER would not change the burn but as the aircraft generally operated at much lighter weights fuel burn should improve


If you operated an ER on the same routes with the same payload, the weight and fuel burn would be the same. You don't take more fuel just because you have a higher MTOM.



This is true


What I’m really trying to see here is how a
purpose built 777A compares to an artificially ‘derated’ ER as SIA operated


Is the MGTOW the same ?

What was the engine thrust on the derated
aircraft?

Etc.,

Interested in a comparison

Re: 777A compared to ‘derated ER’

Posted: Thu Nov 22, 2018 2:52 pm
by BravoOne
While I cannot find a reference for the EOW on a 777A, the 777-200ER is heavier, that I'm sure off. Therefore givien the same payload one could assume that the -200ER is heavier and would burn a greater amount of fuel over the same city pairs on any given day. How much?

Maybe 3% would be my guess all things being equal.

Re: 777A compared to ‘derated ER’

Posted: Fri Nov 23, 2018 6:10 am
by Max Q
Well thanks for the post B1 but that wasn’t really my question


This topic and it’s point has been missed !

Re: 777A compared to ‘derated ER’

Posted: Fri Nov 23, 2018 4:44 pm
by zeke
I think your assumption that the regional 772s were lighter was false, I think they were heavier and still capable of flying 12 hr flights.

They had newer engines which reduces burn.

Re: 777A compared to ‘derated ER’

Posted: Fri Nov 23, 2018 9:42 pm
by Chaostheory
Max Q wrote:
VSMUT wrote:
Max Q wrote:
Maximum take off weight was reduced significantly, albeit ‘artificially’


Operating at similar weights as an ER would not change the burn but as the aircraft generally operated at much lighter weights fuel burn should improve


If you operated an ER on the same routes with the same payload, the weight and fuel burn would be the same. You don't take more fuel just because you have a higher MTOM.



This is true


What I’m really trying to see here is how a
purpose built 777A compares to an artificially ‘derated’ ER as SIA operated


Is the MGTOW the same ?

What was the engine thrust on the derated
aircraft?

Etc.,

Interested in a comparison


The paper mgtow ultimately depends on the operator. Unless there is someone here with access to or knowledge of SIA fleets specs, you're not going to get your answer.

Keep in mind that derate can be very much operator specific. both in terms of max operating weights and engine thrust.

I know for the 772/ER, in addition to SIA, PIA, AF, Saudia and BA operate(d) derated 772ERs.

BA has/had a varying number of max weights whilst I believe AF and PIA derated theirs to ~275t

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 2:50 am
by strfyr51
BravoOne wrote:
Operated a 767-200ER that had AFM reductions in MTOGW. When we wanted to revise it upwards to it's original delivered weights, Boeing wanted a significant charge for this paper mod. I think we did it with a paper STC and saved probably 50K.

The mod to make a B767-200 into a -er was to activate the Center tank in the cockpit with a new fuel panel. All the plumbing and Pumps were already installed so the Mod was pretty quick and the overwater gear just had to be installed. Ai United it was done in a 3 day visit just to install Placards, Seat back Placards, Life Vests. Rafts, New slide rafts on the Doors and to re-weigh the airplane to re-calculate the new weight and Moment. After the first one? All the rest could be done over the weekend for the 18 remainders (we only had 19 B767-222's)

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 8:34 pm
by BravoOne
Thanks, my post was strictly regarding the gross weight adjustments and had nothing to do with coverting a -200 to an ER. Keep in mind that some -200ER's have a full jetison system for the higher gross weight versions.

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 8:38 pm
by BravoOne
zeke wrote:
I think your assumption that the regional 772s were lighter was false, I think they were heavier and still capable of flying 12 hr flights.

They had newer engines which reduces burn.


Actually UAL was having marginal payload/range issues fro Europe to KORD with their A models so I'm not sure where you come up with the 12 hour flights. As others have said, many of these range issue are very operator specific.

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 9:18 pm
by zeke
We are not talking about United, we are talking about SQ.

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 10:25 pm
by BravoOne
Max Q wrote:
Singapore had / has ? some 777ER models
which they deliberately derated for regional operations


I believe this was done by a paperwork reduction of maximum take off and other weights and maximum engine thrust was reduced and limited with electronic adjustment



This gave SIA a much lighter triple that burned less fuel and paid less in landing fees, although it didn’t have the performance of a regular ER it was more than adequate for regional flights


Not the most efficient solution to the mission, later it was covered by the A333
and now the 787-10 is starting to fill that
niche


So how did these ‘derated’ triples compare in weight, engine thrust and performance to the ‘original’ lightweight 777A models operated by UA / BA / CX ?



So how did these ‘derated’ triples compare in weight, engine thrust and performance to the ‘original’ lightweight 777A models operated by UA / BA / CX ?

Sorry but looks to me that UAL is part of the discussion.? Anyway...what difference does it make?

Re: 777A compared to ‘derated ER’

Posted: Sat Nov 24, 2018 11:16 pm
by zeke
No every thread on this site does not need to include “this is what we did at united”, the OP was asking about the SQ regional 77Es.

They were not 77As, they were 77Es with lower MTOW but still good enough to get to LHR and AKL.

Re: 777A compared to ‘derated ER’

Posted: Sun Nov 25, 2018 4:51 am
by Pacific
Wasn't the question about the economies of operating a 772ER paper derated to 772A performance levels versus an actual 772A?

Does a 772A have lower OEW versus a derated 772ER?
How would they compare in fuel burn when flown on the same regional missions?

Re: 777A compared to ‘derated ER’

Posted: Sun Nov 25, 2018 5:12 am
by Max Q
BravoOne wrote:
Max Q wrote:
Singapore had / has ? some 777ER models
which they deliberately derated for regional operations


I believe this was done by a paperwork reduction of maximum take off and other weights and maximum engine thrust was reduced and limited with electronic adjustment



This gave SIA a much lighter triple that burned less fuel and paid less in landing fees, although it didn’t have the performance of a regular ER it was more than adequate for regional flights


Not the most efficient solution to the mission, later it was covered by the A333
and now the 787-10 is starting to fill that
niche


So how did these ‘derated’ triples compare in weight, engine thrust and performance to the ‘original’ lightweight 777A models operated by UA / BA / CX ?



So how did these ‘derated’ triples compare in weight, engine thrust and performance to the ‘original’ lightweight 777A models operated by UA / BA / CX ?

Sorry but looks to me that UAL is part of the discussion.? Anyway...what difference does it make?




Correct

That’s what this topic was about, comparing the A model 777 with those ER
versions, SIA for example that were deliberately downrated by their operators for regional operations

Re: 777A compared to ‘derated ER’

Posted: Sun Nov 25, 2018 5:48 am
by zeke
Pacific wrote:
Wasn't the question about the economies of operating a 772ER paper derated to 772A performance levels versus an actual 772A?

Does a 772A have lower OEW versus a derated 772ER?
How would they compare in fuel burn when flown on the same regional missions?


See above

"I think your assumption that the regional 772s were lighter was false, I think they were heavier and still capable of flying 12 hr flights.

They had newer engines which reduces burn."

The 77E was about 3 tonnes heavier than a 77A.

Re: 777A compared to ‘derated ER’

Posted: Sun Nov 25, 2018 7:27 am
by Pacific
Thanks Zeke for the information. The newer engines burning less fuel despite the 3t weight disadvantage is impressive. Even more impressive because the engines are less than half a generation apart.