aviation

Sep 12, 2013

Wear, tear and quick repair at Sydney Airport

There is an interesting account in the Aviation Herald  of damage being noticed on a Sydney Airport

Ben Sandilands — Editor of Plane Talking

Ben Sandilands

Editor of Plane Talking

Qantas A380 and other heavies pounding the pavements at Sydney: Source Qantas

There is an interesting account in the Aviation Herald  of damage being noticed on a Sydney Airport runway on Wednesday after a Qantas A380 took off for Los Angeles.

The narrative in the report is brief:

By Simon Hradecky, created Wednesday, Sep 11th 2013 19:07Z, last updated Wednesday, Sep 11th 2013 19:10ZA

Qantas Airbus A380-800, registration VH-OQH performing flight QF-11 from Sydney,NS (Australia) to Los Angeles,CA (USA), had just gotten airborne after takeoff from Sydney’s runway 34L in gusting cross wind conditions when the crew of another aircraft advised tower that there appeared to be foreign objects on the runway, a second crew advised the taxiway signs had just been blown over when the Qantas A380 went past. An aircraft on approach was instructed to go around, runway 34L was closed. A crew reported it appeared as if something had exploded on the runway at the left hand side of the runway between taxiways A5 and L, just south of L when the Airbus A380 went past. A runway inspection was dispatched and reported the pavement of the runway had failed. Sydney tower subsequently advised all aircraft that runway 34L was unavailable for at least one hour, a number of departures requiring runway 34L returned to the apron, all other traffic was switched to runways 34R and 25.

VH-OQH continued to Los Angeles for a safe landing.

The airport returned to normal operation with both main runways 34L and 34R available about 5 hours later.

Sydney Airport was quick to fix the damage, and it is fair to say the passage of the big jet may have been a case of pushing cumulative damage to breaking point, since the wheel loadings of the A380 are less per wheel than some smaller and sometimes faster moving jets during takeoff rolls, and the peak stress on runways is delivered through the wheels of landing aircraft.

A note about the Aviation Herald. It always has more detail about Australian incidents and sooner than they are reported on the ATSB web site. It almost always has more photos where relevant, and more topographical maps, and …. more everything.

No-one knows how Hradecky does this and he isn’t telling.  But we are grateful and appreciative.

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11 comments

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11 thoughts on “Wear, tear and quick repair at Sydney Airport

  1. ggm

    So the semantic web now has keywords for this blog which link “sydney airpor” “a380” and “exploding” .. when as you point out, its the runway, something LOOKED like it had exploded, and because the wheel loadings on a 380 are less, its probably damage from something else.

    “frequent lighter plane use destroys landing infrastructure as 380 takes off and exposes it”

  2. Ben Sandilands

    As a general observation, the limitations of automated keyword searches and constructions, and above all, supposedly intuitive word completions and spelling changes are driving many web users nutz. Uh, huts. No, not huts, nuts.

  3. Richard de Crespigny

    Ben: “and the peak stress on runways is delivered through the wheels of landing aircraft”

    Richard: Interesting comment Ben. I’d like to know your reference for this statement.

    You might be correct because there is a higher frequency of landings over a small section of tarmac, and indeed GLS autolands tend to reduce the landing zone to tiny proportions.

    However, practically, the highest stress on the tires is on takeoff (NOT landing) due to TOW > LW and horizontal stabiliser-elevator forces.

    Its relatively common for tires to blow on takeoff, but very rare for tires to blow on landing (I know of none).

    So I can understand (in fact predict) that runways “delaminate” at the rotation point rather than at the touchdown point.

  4. Ben Sandilands

    Richard,

    Much appreciated. Some of your colleagues had informed the view I expressed in the post, however, at this point, with respect for all, I will quietly sit in the background and enjoy expert comments from all directions.

  5. Dan Dair

    I was doing some very minor follow-up that took me to ‘Gravatar’
    & I mistakenly thought “an avatar that add gravitas to your name or subject”
    (not so, as it turns out)
    And then I am privileged to see (the great) Richard de Crespigny, who chooses to add ‘gravitas’ to his name by the use of an image of Virgil Tracy.
    Just outstanding.!!!
    (Or perhaps that’s just a photo of him in his part-time job,? you know, saving the day on a regular basis.)

  6. Mark Parker

    I’m not from the aviation field so I’m not commenting in line with the expertise of others here but I’m intrigued by Richard’s comment re take off vs landing stress on tyres. I do understand that the stress’s on tyres at rotation must be immense – but would the stress’s on the tyres necessarily translate to undetected tarmac damage?

    The reason I ask is based on my experience of driving road trains many years ago in Queensland and the Northern Territory. During these years I learnt from my dad that when your GCM was north of 65 tonnes and often over 100 tonnes you were best advised to get your braking under control early as generally the last 150m+ in the lead up to a stop point (i.e. intersection or lights) was generally the most unstable piece of bitumen due to the stresses of heavy vehicles stomping on the brakes (at the last minute when they realised they were not stopping normally) and causing bitumen ripples and deformation which ultimately lead to surface separation. This was a lesson I learnt the hard way when driving into Cloncurry with (only) two trailers and being unable to pull up in time for the railway line stop sign – we simply bounced the final 30+ meters as the rippled road surface kicked tyres off the road – no tyre on road = no stopping force – luckily there was no traffic on the train line!

    So, before Richard’s comment I would have naturally assumed that the typical landing/braking zone is the zone of the runway that is most at risk – this is in line with my road train/line haul experience. Richard notes that the forces being transmitted through the tyres at rotate due to TOW and the design of modern wings is in fact greater than landing forces…are these forces being transferred into the tarmac in unexpected ways? i.e. straight down on rotate?

  7. Duxnutz

    Virgin’s 777 blew a mains tire just last year landing in Sydney on 34L. I’ve also witnessed at least one 747 blowing a tyre on landing. In both cases I think it was more an issue with the tire itself vs a hard landing.

  8. Rainer

    Could it be that the exhaust of the 380 (and of others) at the rotation-point has led to the weakening of the runway. Has anyone measured the temperature on the tarmac at rotation?

  9. Dan Dair

    Rainer,
    The ‘exhaust’ thrust at`rotation may well be the cause.
    The thrust to get any airliner into the air is substantial, especially if it’s a 4-engined A380 or a large twin such as 767 or 777.
    The heat from that thrust however, I would have thought was marginal. Whilst being quite hot, take-off speeds are approaching 200 miles an hour, so that heat will not be pointing at one area for more than a moment, consequently, no area has the chance to heat-up to a problematic temperature before the heat-source (engines) have moved further along the runway.

  10. Uwe

    Thrust per engine on an A380 is lower than on a 777-300ER.
    Dynamic pavement loading his higher on landings than during
    the start run. ( During touchdown sinkrate is reduced to zero
    in about a foot or two of downward movement : easily 1.5g or more deceleration ).
    What I could imagine is an A380 producing a higher (air)pressure differential over the runway surface and thus having a better chance of lifting up some debris ( see the “exploded” observation).

  11. TomM

    I’m no aviation expert, but on the takeoff run, the point of highest loading on the runway from the tires only should be at the start of the run. At rotation, the load should be minimal on the tires as the wings are now bearing the mass of the aircraft and hence starting to fly. Other factors (engine thrust, pressure change as wing passes over etc.) should be dominating runway loading at rotation.

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