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StereoTechque
Topic Author
Posts: 186
Joined: Sat Nov 28, 2015 7:24 am

Increase in MTOW

Tue Oct 16, 2018 6:18 pm

The A320 Neo's at the Airline I work for have come with Three MTOW'S. 73.5 initially, then 74 and now in 79T. How does the Airframe become more capable of lifting heavier loads after a certain point of time? I know the engine thrust rating is same in all three..
Looking California.. Feeling Minnesota.... R. I.P. Chris Cornell...
 
wing
Posts: 1366
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Re: Increase in MTOW

Tue Oct 16, 2018 7:24 pm

The airplane is designed to operate with 79Ts.The higher the MTOW , higher is the landing,overflying etc. fees are.If your operations require short haul,low cost than you go with 73,5 T and save money from operational costs but if you require a longer range,higher density operation than you pay certification fees to Airbus than your airplane is certified to 79 Ts.
Summary;the more money you pay the higher load can your airplane carry :)
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Wacker1000
Posts: 226
Joined: Tue Jan 07, 2014 6:36 pm

Re: Increase in MTOW

Wed Oct 17, 2018 12:04 am

StereoTechque wrote:
THow does the Airframe become more capable of lifting heavier loads after a certain point of time?


In certain cases you only have to write a check and someone will hand you a piece of paper saying so.
 
GalaxyFlyer
Posts: 5635
Joined: Fri Jan 01, 2016 4:44 am

Re: Increase in MTOW

Wed Oct 17, 2018 2:29 am

In other cases, live with some compromises in performance-lower initial cruise level, greater fuel burn, maybe use more runway for take-off. There are “lines in the sand” both structural and performance that cannot be crossed, but fair latitude before reaching them.

GF
 
StereoTechque
Topic Author
Posts: 186
Joined: Sat Nov 28, 2015 7:24 am

Re: Increase in MTOW

Wed Oct 17, 2018 4:56 am

Wacker1000 wrote:

In certain cases you only have to write a check and someone will hand you a piece of paper saying so.


Haha.. Initially when the A320s rolled out they were having a MTOW of around 65T. Current 320 are around 77T. Your cheque writing might work for a few tons but in this case there must be something more..
Looking California.. Feeling Minnesota.... R. I.P. Chris Cornell...
 
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SAAFNAV
Posts: 603
Joined: Wed Mar 17, 2010 5:41 pm

Re: Increase in MTOW

Wed Oct 17, 2018 6:47 am

StereoTechque wrote:
Wacker1000 wrote:

In certain cases you only have to write a check and someone will hand you a piece of paper saying so.


Haha.. Initially when the A320s rolled out they were having a MTOW of around 65T. Current 320 are around 77T. Your cheque writing might work for a few tons but in this case there must be something more..


I'll expand the OP's question: I think we all understand that you pay for different weight variants.
But what changes in the life of an airliner design that permit the growth of max weight?

Is it just validation of data that proofs the longevity of the original design? Are parts designed differently? New parts added?
Engine upgrades are one part of the puzzle, but there's a lot more to the structural limits than just thrust.
CFI/Gr. III, L-382 Loadmaster, ex C-130B Navigator
 
WIederling
Posts: 9291
Joined: Sun Sep 13, 2015 2:15 pm

Re: Increase in MTOW

Wed Oct 17, 2018 8:43 am

Small hardware changes, fiddling with FBW, flight data on cyclic loads that indicates bigger available margins, ..
Look into specced service life and extension efforts too. Max loads and max cycles/max hours interact.
Murphy is an optimist
 
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zeke
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Joined: Thu Dec 14, 2006 1:42 pm

Re: Increase in MTOW

Wed Oct 17, 2018 10:25 am

StereoTechque wrote:
The A320 Neo's at the Airline I work for have come with Three MTOW'S. 73.5 initially, then 74 and now in 79T. How does the Airframe become more capable of lifting heavier loads after a certain point of time? I know the engine thrust rating is same in all three..


You will find they paid for the higher weight landing gear, should be a placard on the gear to reflect the highest MTOW. The other MTOWs would have different MLWs to improve maximum payload over shorter routes.
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
SteelChair
Posts: 1428
Joined: Fri Aug 25, 2017 11:37 am

Re: Increase in MTOW

Wed Oct 17, 2018 11:42 am

I believe the maintenance check intervals for some structural inspections change (become more frequent or stringent) as a result of higher weight.
 
LH707330
Posts: 2317
Joined: Fri Jun 15, 2012 11:27 pm

Re: Increase in MTOW

Wed Oct 17, 2018 6:52 pm

StereoTechque wrote:
Wacker1000 wrote:

In certain cases you only have to write a check and someone will hand you a piece of paper saying so.


Haha.. Initially when the A320s rolled out they were having a MTOW of around 65T. Current 320 are around 77T. Your cheque writing might work for a few tons but in this case there must be something more..

The A320-100 did have a lower MTOW, the 200s were slightly beefed up and came with the tortilla chips as standard.

Certain other aircraft also got beefed up over their lifetimes to enable higher weights. For example, SQ's A340-300s were specifically bought for SIN-CDG and were the first of the 313X variant, with MTOW upped from 257t on the 311 and 312 to 275t on the 313X. IIRC that became build standard in 1996, because other operators enjoyed the extra range as well. This model had an extra ~500 nm of range, and effectively killed off the business case for the A340-200.
 
Chaostheory
Posts: 1149
Joined: Wed Mar 06, 2013 2:09 am

Re: Increase in MTOW

Fri Oct 19, 2018 6:18 pm

When I flew for a now defunct UK airline, the CAA allowed us to operate the A319/320 under a flexible MTOW scheme. One sector we may be flying at 73.5t and the next may be upped to 75 or 77t.

As for how an aircraft family's MTOW grows from a low baseline to 78 or 79t, that is largely down to a bunch of boffins called stress engineers.
 
StereoTechque
Topic Author
Posts: 186
Joined: Sat Nov 28, 2015 7:24 am

Re: Increase in MTOW

Sat Oct 20, 2018 12:23 am

Chaostheory wrote:
When I flew for a now defunct UK airline, the CAA allowed us to operate the A319/320 under a flexible MTOW scheme. One sector we may be flying at 73.5t and the next may be upped to 75 or 77t.


Great. Never heard of such a practice before.
Looking California.. Feeling Minnesota.... R. I.P. Chris Cornell...
 
WIederling
Posts: 9291
Joined: Sun Sep 13, 2015 2:15 pm

Re: Increase in MTOW

Sat Oct 20, 2018 9:29 am

StereoTechque wrote:
Chaostheory wrote:
When I flew for a now defunct UK airline, the CAA allowed us to operate the A319/320 under a flexible MTOW scheme. One sector we may be flying at 73.5t and the next may be upped to 75 or 77t.


Great. Never heard of such a practice before.


Isn't that what the Airbus "Flex" VVs ( handoff between MTOW and MZFW ) allow?
Murphy is an optimist
 
Chaostheory
Posts: 1149
Joined: Wed Mar 06, 2013 2:09 am

Re: Increase in MTOW

Sat Oct 20, 2018 3:50 pm

WIederling wrote:
StereoTechque wrote:
Chaostheory wrote:
When I flew for a now defunct UK airline, the CAA allowed us to operate the A319/320 under a flexible MTOW scheme. One sector we may be flying at 73.5t and the next may be upped to 75 or 77t.


Great. Never heard of such a practice before.


Isn't that what the Airbus "Flex" VVs ( handoff between MTOW and MZFW ) allow?


Not quite

The "Flex WVs" you're referring to are in Airbus terms called dynamic payload variants. This is where you you can trade range (mtow) for payload (mzfw). On the A330 where it's available as an option, if you operate at 235t mtow, your mzfw is limited to 173t. Alternatively, if you fly at 233t mtow, your mzfw is 175t. I don't quite remember the formula but I know it doesn't scale linearly.

As mentioned by Zeke up thread, the flexible mtow schemes permitted by some CAAs allows you to change weight variants as your ops department sees fit. So if you jump from a 73.5t to 78t mtow wv, the associated mzfw and mlw limits increase too.

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