A320 LAF(Load Alleviation Function) Re-introduced.
 

Ladies and Gentlemen the LAF has been reintroduced in the sharklets:cool:


The LAF (Load Alleviation Function) Unloads the stresses on the wing by momentarily deploying the Flight spoilers(Spoiler No. 4 and 5) and deflects BOTH Ailerons upward. This function is so fast that it is hardly noticeable.


Please Share some knowledge regarding this and correct me if i'm wrong.

Q. How do you know LAF is active?

A. Turn up the speaker and you'll hear 'hahaha'.

There are no normal or irregular procedures associated with it. There are no buttons to press. It is just flight control info they put in the FCOM to make it even bigger and thicker than it already is.

We have no control over it and cannot turn it off. It is not something I need to know about.

Sharklets are a promise Airbus has not been able to keep. The design is patented by a small company closely associated with Boeing (but not Boeing itself). Airbus is not willing to pay patent royalties.

In the early days, IIRC, there was an altitude restriction above a certain weight if the LAF was u/s. After several years, this was rescinded.

As planeboy_777 says, Spoilers 4 & 5, plus the aileron, are used on both sides. There are one or two (sorry, memories fade) hydraulic accumulators on each wing, to provide proximate fluid rapidly.

The LAF accumulators, with their direct-reading gauges, are partly visible when the flaps are extended (through the slot). Like all accumulators, they have an air (nitrogen) precharge. This used to be monitored by a low-pressure switch. This would provoke an ECAM warning "F/CTL LAF ACCU FAULT" when the hydraulic pressure had dissipated after engine shutdown. This warning would typically disappear within a minute or two, by which time the cold-soaked accumulator had warmed up a bit. If so, it could be topped up on the next long turnround or night-stop at base.

Enjoy!

I assume this is to reduce the strengthening required of the outer wing to fit sharklets thus reducing overall weight of the aircraft.

I wonder if the sharklet retrofit will require LAF activation or this will just be on new aircraft. I thought the LAF was removed, so I assume accumulators (as per Chris Scott) will have to be installed? Anyone know any more?

The other issue on wing-bending relief, of course, would be fuel management. That is: if and when you are allowed to pre-empt the scheduled fuel transfer from outers to inners.

Forgotten the rules now, but we sometimes used to do it manually (using the fuel xfer circuit-breakers) before landing in winter. That was after a fairly long sector, if humidity on the airfield was likely to cause frost formation on the skin above the outer tanks, if still full of cold fuel. (Arriving with them empty meant that, on refuelling, the warm fuel going into the outer tanks would avoid that problem.)

It's not official but there's a bit of info:

Flight Control Laws | Normal Law - Load Alleviation Function

@ planeboy777

You could change 'Gentleman' to gentlemen for a start :E

Can you write Hindi/Urdu/Arabic or Latin better than he does English?

Excelent. Topping up accumulators on a nightshift again. Kerching. ;)

LOAD ALLEVIATION FUNCTION (LAF) ACCUMULATORS
Four additional accumulators perform the load alleviation function. These accumulators (one for the green system and one for the yellow system on each wing) maintain the required pressure during high-rate operations of the various movable wing surfaces.
Note : To reduce wing bending loads in turbulence (due to discrete gusts), the ailerons and outboard spoilers are deflected to reduce G loads whenever actual G is 0.3G greater than expected.(difference between pilot demanded load factor and aircraft load factor)... It is active only in normal law and in clean config.

While aspects of the load-alleviation function was originally introduced for a specific certification purpose, these subsequently became redundant. The software was removed, although the mechanical systems in the wing remained in place.

But Airbus has concluded that, with new software, it use the load-alleviation system to increase the A320's payload-range capability.

From a recent airbus event I attended we were told that the LAF function would be re-introduced for the sharklet NEO & retrofit aircraft. However it would be a software function only. No additional hardware (accumulators) would be required. They are indeed supposed to help with the wing loading. There are also mods to the spoiler authority to prevent excessive wing loads.

USMC - Sharklets are here for airbus. There are several a/c flying with them installed for evaluation & proving. Sharklets are supposed to be different from blended winglets ala Aviation Partners Boeing.

EIU-EEC,

Thanks. Yes, 2 LAF accumulators (Green and Yellow) per side makes sense. Spoilers 4 use Yellow, Spoilers 5 use Green, and Ailerons use Green (as well as Blue).

Quote from mono:
"However it would be a software function only. No additional hardware (accumulators) would be required."

How could it work without hardware, incuding accumulators? It has to be lightning-fast: much faster than the normal control inputs. Perhaps it means "additional to the existing"?

Since LAF software was discontinued, have A320s continued to be made with some or all of the hardware, including the accumulators? If not, that information you quote doesn't make sense.

Wasn't the L1011 fitted with something like that 40 years ago?

Single Chime: Yes, the Active Control System controlling the outboard ailerons.

I only remember one accumulator on each side? - we used to top them up with nitrogen each turn at LHR on the old -100 series (ex BCal) BA G-BUS aircraft.

Greetings Marvo, quotes:
"I only remember one accumulator on each side?"

I couldn't remember either, so I looked at my first FCOM, dated 17 Feb 1988 (!), for the BCAL-ordered 100-series (G-BUSB/C/D/E/F). It clearly states the LAF operates Spoilers 4 (Yellow hydraulics) and 5 (Green), as well as Ailerons (Green & Blue). So there must have been two, surely? Maybe only one was visible when we extended the Flaps... Could it have been the other one that needed topping up? ;)

"we used to top them up with nitrogen each turn at LHR on the old -100 series (ex BCal) BA G-BUS aircraft."

Rubbish! You engineers never cease moaning. :ugh: BTW, the BCAL-ordered 200s (G-BUSG/H/I/J/K) definitely had the same system, but perhaps the accumulators were less leaky? Can't remember if the much later, BA-ordered, A319s had it.

mono
 

There are several a/c flying with them installed for evaluation & proving.
This is not correct, Airbus has full certification for the modification and will shortly also have it with the A319 & A321.
I believe all A320FAM aircraft now being delivered have the wing modification (provision for Sharklets) embodied. It is an option at the moment on the A320 to install the Sharklets, however not on the A321 until certification has been completed.

I beg to differ Spotty!

Airbus’ "Sharklet" wing-tip devices took to the sky for the first time on 30 November 2011 with a successful maiden flight using an A320 development aircraft. This nearly five-hour flight from Toulouse, France kicked off a multi-month test campaign to validate the Sharklets’ performance, confirm their aerodynamic behaviour and gather data for certification. Sharklets are expected to reduce fuel burn over long sectors by at least 3.5 per cent, representing an annual CO2 reduction of approximately 700 tonnes per aircraft.


That quote is taken direct from the airbus website. How can you have certification for a product if you haven't flown it for certification purposes??

On top of that, AirAsia became the first customer to receive an A320 equipped with Airbus’ Sharklets wingtip devices on 21 December 2012.

sharklets - Videos - AIRBUS.

The link shows some relevant info regarding sharklets.

Do try to keep up old chap!

mono
 

I will stick with my previous statement, certification flying has finished for the A320, Air Asia as you said was the first airline to receive sharklet fitted A320s.
You cannot put an aircraft into service without full certification, which was announced on the 3rd December for the CFM powered A320CEO.
Certification flying is still continuing on the rest of the A320FAM. :ok:

JetBlue is preparing to start retrofitting the Sharklets on our A320 fleet and we've been informed that the LAF will be active and there are some changes to the spoiler deployment on autolands to compensate for a bounce tendency discovered in testing.