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...
I think the key understanding to clarify here is whether the aircraft flew two more sectors after the hard landing:
If the press release by SATA is to be taken seriously discarding the obvious date error, the airplane would have flown two more sectors after the accident despite substantial damage to the landing gear and missing rivets in the structure of one wing.
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?
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.
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?
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!
Last edited by Locked door; 20th Aug 2009 at 20:43.
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?!
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?
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.
Narrative: The descent and approach was made in strong tailwind. A change of runway, the strong tail wind and the shortened approach path resulted in the aircraft becoming high on the approach profile. The unstabilized final approach was abandoned at low altitude (580 feet), and during the go-around the aircraft entered an extreme manoeuvre with high positive and negative pitch attitudes, and the aircraft exceeded maximum negative and positive g-values. The aircraft reaced attitudes of -49degrees to 40degrees and a load factor of +3.59g. The speed limits were exceeded. After the upset the aircraft was flown for another approach and landed at the airport at 11:02. The aircraft structure appeared not to be damaged.
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.
ps. That Icelandair incident (so nearly a hull loss) couldn't have happened on an airbus (time to feed the trolls.....)
This thread is straying from the original ARC (Abnormal Rwy Contact), into another interesting (understudied) subject of UNSTABLE Go-Around.
A few slots above, commenting on B757 IcelandAir G/A- UPSET at Oslo: "... couldn't have happened on an airbus ..."
But there were numerous analogous G/A pitch UPSETs aboard AirBus [??] before that B757 example:
-- China Air Flt 140 / 26Apr94 ... A300-600R lost control, crashed during APPCH at Nagoya, 1000' agl inadvertantly selected G/A mode on Throttle's Palm-switch; ... Horizontal Stab had moved to max deflection aircraft nose up. Aircraft pitched up to 36 degrees nu, airspeed decaying, rolled right, impacted tail first ... @ 400' Alpha floor triggered and both engines accel to max thrust, stab trim abnormal, nose pitches up uncontrollably, max pitch 36-52 deg @ 22 sec after Alpha Floor activation. GPWS and Stall warnings. sob = 14+257. Fatalities = 264.
Cited three similar incidents:
-- Finnair A300 on approach at Helsinki, Jan '89, sudden pitch-up to 35 deg;
-- an Interflug (German) A310 pitch-up to 88 degrees during a go-around at Moscow/Sheremechevo in '91; and
-- Tarom (Romania) A310 approaching Paris in 24Sep94;
all recovered and landed safely.
[AWST May 9 '94, pg 31+; & Feb 13 '95 pg 32; RAeS "Aerospace" Apr '95.]