EY Emergency Landing in BNE

[markis10]

Yes - the Birgenair B757 was parked for 20 days or so and allowed mud wasps to build a nest in one of the the pitot tubes, but, given the EY A330 would only have been on the ground for a few hours at BNE (maybe overnight at most?) it is interesting to note how quickly those wasps can apparently build a nest or maybe build up an obstruction over time, with one final grain of sand/mud being the difference between an embarrasing emergency and something even worse.

Which is why you should always cover them when parked!

 

[eastwest101]

Which is why you should always cover them when parked!

I agree - I am guessing it is (or should be) standard operating procedure. A quick question - what is the definition of "being parked", i.e. is it aircraft idle for 2hrs, 6hrs, 10hrs or 12hrs ? Planned to be idle for 3hrs but ends up being 6hrs due to delays? Or is it something else entirely? Like once wheels are chocked it is considered to be parked. I guess this is what the ATSB will be looking into with the EY A330 at BNE.

The other interesting thing is the 3 pitot tube set up common to most Airbus and I presume Boeing aircraft, and the fact that you can switch over the airspeed indicators and ADRIU's between the three. And the findings from the B757 incident in 1996 where one pitot tube out of the three is misleading can result in misleading and unintentional/conflicting data and warnings in the coughpit. Lots of interesting questions to answer here!

 

[markis10]

I would define parked as when the engines are off.

 

[omgbomb]

Odd for this not to be noticed when the pilot does their walkaround before a flight? (don't know if that's standard practice by Etihad)

 

[markis10]

Odd for this not to be noticed when the pilot does their walkaround before a flight? (don't know if that's standard practice by Etihad)

It was inside the device and only visible once at the lab.

 

[omgbomb]

It was inside the device and only visible once at the lab.

I see, thanks.
Scary they can build a nest so quickly!

 

[albatross710]

With a blocked pitot think about what happens

1. On the ground : no difference

2. On take off roll, no airspeed likely to be indicated from the blocked tube, but others working OK

3. As aircraft altitude increases, instead of the ram air coming into the tube to indicate airspeed the pressure difference from the altitude starts to erroneously indicate airspeed. The ground level air trapped inside the pitot starts to put pressure onto the device and the indicator starts to show airspeed.

4. As the altitude increases, so does the indicated airspeed on the device with the blocked pitot. As it goes overspeed, then the pilots inherent response may be to raise the nose (to reduce airspeed) but which will increase altitude and increase that indicated bogus airspeed even more.

I guess the really good pilots notice it at step 2.

 

[eastwest101]

Odd for this not to be noticed when the pilot does their walkaround before a flight? (don't know if that's standard practice by Etihad)

Quite high off the ground so maybe difficult to inspect or see the inside of a pitot tube during a walk around? I am not an expert but maybe pilots or ground crew have ladders/stairs to check flight instruments? A pilot may notice that the pitot covers are not on when they do their walk around, but maybe only a very studious/OCD pilot whom may check with ground crew along the lines of "who took off/put on the pitot tube covers and when?

 

[albatross710]

Quite high off the ground so maybe difficult to inspect or see the inside of a pitot tube during a walk around? I am not an expert but maybe pilots or ground crew have ladders/stairs to check flight instruments? A pilot may notice that the pitot covers are not on when they do their walk around, but maybe only a very studious/OCD pilot whom may check with ground crew along the lines of "who took off/put on the pitot tube covers and when?

On the RAAF flight line I recall we used to remove the covers as pilots came out to the aircraft. OMG, one distance memory was with the Canberra bombers where the pilot would inspect the (9?) covers once we had removed them.

Pitot tubes are heated in flight, so from memory they cannot be immediately fitted after landing.

And final btw, "Blowing" into a pitot tube is bad news and will result in instrument failure.

 

[erkpod]

Which is why you should always cover them when parked!

And then remember to remove the covers before the next flight.

 

[ozbeachbabe]

Quite high off the ground so maybe difficult to inspect or see the inside of a pitot tube during a walk around? I am not an expert but maybe pilots or ground crew have ladders/stairs to check flight instruments? A pilot may notice that the pitot covers are not on when they do their walk around, but maybe only a very studious/OCD pilot whom may check with ground crew along the lines of "who took off/put on the pitot tube covers and when?

Engineers may be able to see a blockage if they looked into the pitot tube however visually inspecting pitot tubes is not normally part of an engineers walk around inspection for larger aircraft due to them being too high off the tarmac.

Smaller aircraft eg Dash8 aircraft have inspection of pitot tubes on both the engineer & pilot checklists as they can be viewed from the ground. Military aircraft eg F-111's & F/A-18's have pitot tubes on the pre-flight checklist inspection for pilots & engineers also.

After the initial rejected take-off engineers could always have used a pitot static test kit to check the airspeed after the adiru's were swapped around & the MEL applied.

 

[Happy Trails]

Those wasps are a pain in oil & gas too.
They can find their way into sensitive equipment and the mud sets like cement.

 

[SeatBackForward]

Those wasps are a pain in oil & gas too.
They can find their way into sensitive equipment and the mud sets like cement.

Sorry have to put on my engineering hat...

Sets like concrete. Cement is a powder used to make concrete, along with sand aggregate and water.

 

[markis10]

Sorry have to put on my engineering hat...

Sets like concrete. Cement is a powder used to make concrete, along with sand aggregate and water.

While cement is indeed a component of concrete, it's also a resonable thing to say the mud sets like cement, given cement is a binder.