SATA brand new A320 ; hard landing in Lisbon
 

rumors about a real hard landing (4.6G) on a brand new SATA A320 in Lisbon (Portugal)

quote AVHerald : SATA A320 at Lisbon on Aug 5th 2009, 4.6G landing By Simon Hradecky, AVHerald

A SATA Internacional Airbus A320-200, registration CS-TKO performing flight S4-124 from Ponta Delgada to Lisbon or flight S4-466 from Funchal to Lisbon (Portugal), experienced a very hard landing on Lisbon's runway 03 causing substantial damage to the airplane. No injuries occured.

The airline reported in a press release, that the newest airplane of their fleet, which entered service only in May 2009, will be out of service until September to repair the damage following the heavy landing on Lisbon's runway 03. The accident occured at the end of a flight originating in Ponta Delgada on Aug 6th...

source : http://www.avherald.com/h?article=41e7623d&opt=0

I think the key understanding to clarify here is whether the aircraft flew two more sectors after the hard landing:

Just out of interest:

1) What's the max "g" loading that an A320 (or indeed any commercial acft) can have on landing without structural damage? What kind of "g" loading would effectively result in the aircraft being declared a write off (for example, the FR aircraft at CIA, last Nov)?

2) Is it possible to translate this into a descent rate - e.g. 12-15'/sec?


Photos: Airbus A320-214 Aircraft Pictures | Airliners.net

Airliners are certificated to a rate of descent and weight combination. Sadly it is not easy to turn this into a simple g reading as the value that would be shown on any particular g meter would depend in where it was mounted and indeed the nature of its mounting.

Clearly people experienced on a particular aircraft type may well be able to correlate damage (or not) to a particular g meter reading but that is not the same thing as coming up with a simple number to cover a range of types.

Airliner airframes structural mininums are:

Up 3G
Fwd. 9G
Down 6G
Laterally 1.5G

Question about the fwd load rating
 

Okay, this makes me curious. What is the reason for a 9G fwd requirement? Seems to me longitudinal accelerations would be pretty small normally (less than 1 G). Is it something to do with withstanding minor taxi collisions?

Or is it just a typo - should have been .9G perhaps?

The 9G could be taking into account a sudden deceleration such as running off the runway end and ending with the nosewheel in soft ground which would stop the aircraft quite rapidly?

In practical terms how is it possible to land a plane at 4.6g? Even if you don't flare and ram it straignt in it would surely be less than that?

IIRC the A320 family a/c have a mandatory hard landing check after a touchdown of 2.6G or more, regardless of a/c weight.

The G is as measured by the IRS's. An auto print out of the landing stats +- 5 secs from first main gear touchdown comes out on the acars printer so there's no way the flight crew could miss it.

4.6 G is achieveable, my company had a 3.5G touchdown during windshear. They touched down with a lot of backstick and TOGA power applied and flew it off the bounce. Less or no corrective action would have resulted in a much harder landing. The a/c was found to be undamaged after the check, airbus build 'em strong!

even when its calm, lisbon can be sporty....when its windy, one has to be at the top of their game....period.

Hello,

The hard landing was not in Lisbon, but in Ponta Delgada in Azores on the 4th of August .

It flew at least 1 more time in the 5th of August.

How could the crew possibly think it was ok to fly the aircraft after a 4.6G landing? Or, how could a first engineering inspection not spot obvious damage such as popped rivets?! :confused:

If it is subsequently found that the crew have been "economical with the truth" w.r.t tech log entries/tried to cover it up, I would imagine no biscuits - possibly no tea.

Reminds me of the Scandi (Finnair?) botched B757 go around (which when you read the report will give you goosebumps). That wasn't entered in the log and the aircraft flew for several days before being inspected. It was found to have been majorly overstressed. Don't know what happened to the crew.....

Think about your fellow aviators who are about to take the aircraft from you. Would you want something kept from you?

A4

A4,

I do believe that you mean the Islandicair botched approach and go-around to ENGM where all thinks went out of control for a period of time :=.

Mj

A4,

do you hvae a link to this report? Finnair guys look mysteriously at me when asked...do you mean as the other poster said the ENGM incident?

fc101

You can calculate the minimium g if you know the vertical velocity and the "stopping distance". The stopping is roughly the vertical undercarriage travel.

From the equations of motion..

V^2 = U^2 + 2aS

V = final vertical velocity (hopefully zero)
U = Initial velocity (rate of descent at contact)
a = acceleration (will be negative in this case)
S = displacement (undercarriage travel)

This makes a lot of assumptions but it gives the minimium g that will be experienced. In practise the shock absorber won't be linear and I guess it may "bottom out" under high load. That would increase the g considerably.

"a" will be in meters per second. Needs to be divided by 9.8 to get a "g" ratio.

Edit: Report shows this to be irrelevant though. The peak g occured in the air.

fc101
 

Here you are:

ASN Aircraft accident Boeing 757-208 TF-FIO Oslo-Gardermoen Airport (GEN)

DB

wow that was some ride.

Altflaps,

Ask your companies engineers about the build quality difference between A & B. The reason the a320 hard landing limit is so high is that they're solid bits of kit. If it had been a 737 or 757 that touched down at 3.5G we'd have been picking bits up off the runway.

Don't let your (unjustified) prejudices about flying airbusses lead on to the structure too.

LD

ps. That Icelandair incident (so nearly a hull loss) couldn't have happened on an airbus (time to feed the trolls.....)

Printout or not depends on the programing

So, do we know for sure yet, whether the aircraft flew again after the "4.6g" touchdown? Is there some kind of incident report out yet?

IGh - the go-around upsets you're referring to were on an Airbus A300. The A320 types wouldn't have behaved the same way, although mode-confusion/vestibular disorientation is a factor in at least three 320 go-around accidents - two in the Ukraine, (Black Sea was one?) and Gulfair at Bahrain if I recall.

I'd say the G load was only a sideshow in the context of the expletitves from the encampment near Mullingar!
More to the point are the two still even there, given the culture that seems to exist in that organisation?

Got ryr the unenviable distinction of the first Irish airline operated jet hull loss ever

4.8 g
 

The hard landing achieved 4.82 G´s. The maximum permitted was 2.6 G´s.
The AC is doeing a deep inspection in TAP Air Portugal.

I always understood that the design landing limit equated to a touch down at 1000ft per/min at max weight + proof factor.

This equates to an unflared landing after a 3 degree glide path with the max permitted tailwind. :8

@IGh

You are correct regarding the A300's and A310's...... but they are not FBW aircraft. If I recall these events are similar to the Iceland B757 i.e. fighting the THS/trim.

Whilst it is possible to make a horlicks of any go-around, the current FBW family of Airbus products do provide a great deal of protection. Go around in an (current) Airbus is straight forward..... push the levers to TOGA and either let the A/P do the work or just pitch to SRS and engage the A/P. Simples! If in the excitement you over pitch then the protections should help you.

There was an A330 loss during a test flight at TLS during a go-around.... can't remember the details but I think it involved a simulated engine failure during the go-around/ altitude aquire (ALT*) phase with insufficient altitude to recover :(

A4

An update to the Aviation Herald entry on this incident says:

"Portugals "Gabinete de Prevencao e Investigacao de Acidentes com Aeronaves" (GPIAA Aviation Accident Branch) told The Aviation Herald on Aug 21st, that they are not investigating the occurrence."

NOT investigating the occurrence? Can't understand why not; I'm presuming the GPIAA works under the same rules as the AAIB and the AAIB certainly would be, particularly given allegations that the aircraft may have flown another sector following the incident.

IGh,

I think most of the comments regarding Airbus are references to its control laws and the FBW philosophy and then meaning the 320, 330 and 340s. Your examples are for the A300/310 which are more "standard", whatever that means.

This thread is (should be) more about a hard landing in an A320 rather than an unstable approach in a 757.

But please let's not turn this thread into an AvB

fc101
E145 driver

16.6 ft/s - I'd say that sounds about right for an extreme liimit

12~15 ft/s is normally what's quoted

The vertical speed and weight limits, are more a measure of the kinetic energy absorption of the u/c. beyond that G ^ rapidly and is not directly calculable

4g at 15 ft/s implies a very small deceleration displacement (6" to 9"), implying the u/c has already done the best it can and we are into plastic deformation territiry

Very surprised indeed if 4.6 G recorded and that deep inspection doesn't find damage

PS. There is a big difference between wingborne G loads (+6/-3) and a landing impact.
The former involves primarily udls (uniformly distributed loads), airframe pressures often largely mitigated by inertia.(alleviation)
The latter more like point loads exacerbated by inertial considerations.

The whole story cannot be told by a single 'g' figure, as John Farley said quite way back. But a central body 'peak G' does give a comparison figure, and thus a measure of likely structural damage..

I have exhausted 'search' and cannot find it, but there was a ?330? thread a while back about a heavy landing which grounded the a/c for weeks with major u/c mounting damage I think - Manchester? Anyone recall?

I believe this is the thread you refer to http://www.pprune.org/rumours-news/2...nding-sfb.html

Aircraft was ferried back from SFB to MAN for repairs

Regards,
G-BPED

From my recollections (not yet hazy...) it is not the first bounce, on a "hard" landing, that causes the excessive acceleration and damages the plane, but the next more or less controlled landing (or crash landing)...I was always taught, if after a miscalculated flare, the plane really bounced back into the air , to GO AROUND, forgetting any pride. If not, Airbus tells not to try to flare again, but to wait with sidestick in the neutral position, and control the descent with a little thrust, but insists you should go around. I do not know if this was the case here, but after bouncing, trying to soften the next touchdown with stick back, decaying speed, nose very high, leads to catastrophic impacts. But you all know that...just to show I am not napping...The A330 at Toulouse was a take-off and another matter completely.

Some rivets disapered and others found loose.

Thanks G-BPED - that appears to have been 2.7g, and both imain gear replaced.

NARVAL;
That is precisely correct both tactically (SOPs), and as seen/experienced.

I would strongly agree with Narval. It would be very difficult to obtain a 4.6g if you try to fly the aircraft into the ground. It usually happens when the aircraft pops up into the air again, looses lift, stalls and "falls" on the runway. The situation can be seriously aggravated if the lift dumpers extend after the first bounce and destroy even more lift.

Dani

Dani;

Yes, fully agree.

So then - do we know, officially, whether this airplane flew after the hard landing or was it grounded?

Flew. The hard landing wasn´t at Lisbon.

BOAC, not sure if this was the thread you referred to, but it was a TCX 320 at BRS which ended up in MAN hangars. I am typing from memory as I have not re-read the thread but hopefully this is the link.

http://www.pprune.org/rumours-news/2...par-crack.html

Thanks for that, lurkio- could not see a g estimate there though.

Just a small clarification on this:

The above quote is referring to § 25.561 of the FARs. That requirement is about aircraft crashworthiness. Aircraft structure is not designed to withstand those levels without damage. The requirement is that the aircraft structure be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing. The acceleration levels quoted above are those felt by the occupants. In addition, the attachments for items of mass in the aircraft which cannot be positioned so that, if they break loose, they do not injure occupants, pierce fuel tanks, or block emergency egress, must also be designed for those acceleration levels.

So, for example, the mounting system of the APU must be designed to withstand the loads produced by those inertia levels applied to the mass of the APU. Otherwise, in a "minor" crash landing, there is a risk that the APU breaks loose and causes hazards for the occupants of the aircraft.

§ 25.473 "Landing load conditions and assumptions" specifies 10 fps at design landing weight, or 600 fpm, and 6 fps at maximum take-off weight, or 360 fpm. Aircraft structure is designed so that no permanent deformation occurs at the maximum loads induced by these landing conditions, over a range of aircraft mass distributions, landing attitudes and landing speeds. The structure is designed not to fail (although permanent deformation can occur) for loads up to these maximum (limit) loads mulitiplied by an ultimate factor of 1.5. In addition, the landing gear itself is tested to reserve energy conditions (§ 25.723), a 12 fps descent rate at design landing weight, which corresponds roughly to the ultimate factor of 1.5 (12^2/10^2 = 144/100 = 1.44). The landing gear structure is designed not to fail up to the reserve energy condition.

It's important to note that the FARs allow the manufacturer to make the assumption of 1g wing lift in the load calculations. Therefore, the 10fps and 6fps landing descent rates are steady-state conditions. In bounce situations, with lift dump deployed, the aircraft can land considerably harder than it was designed for, due to the lack of lift on the wings.

It's also important to note that not all of the aircraft structure will be designed by landing loads. Many flight load cases are more critical.