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MAS A330 BNE leaves pitot covers on

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MAS A330 BNE leaves pitot covers on

Old 25th Jul 2018, 22:54
  #81 (permalink)  
 
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The importance of pushing back against commercial pressures (and how to go about it) is literally taught as part of an Engineering education.
Ha! Tell that to one of our wonderful Aussie ($afety first) airlines.....Engineering On Demand usually means "nil time to rectify" then a deferral. Commercial pressures are going to kill us one day.

Important to remember, the crew didn't follow a bunch of fvckups with one very big fvckup, pilots are still the last line of defence.
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Old 25th Jul 2018, 23:41
  #82 (permalink)  
 
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Forgive me if I haven't read the thread thoroughly enough but is the picture in post #10 of the incident aircraft? Furthermore, do we know for a fact that the pitot covers were left on? The preliminary report doesn't say that. Perhaps they were just being charitable?
Rgds
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Old 26th Jul 2018, 04:52
  #83 (permalink)  
 
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Originally Posted by Fris B. Fairing View Post
Forgive me if I haven't read the thread thoroughly enough but is the picture in post #10 of the incident aircraft? Furthermore, do we know for a fact that the pitot covers were left on? The preliminary report doesn't say that. Perhaps they were just being charitable?
Rgds
Yes it is a fact that the pitot covers were left on. ATSB preliminary reports are just a brief statement of facts about the flight (eg..... airspeed indications failed, they came back). They do not attribute any causes or suspected causes.

For the others here (speaking as a current aussie A330 pilot):

1) BNE has an ongoing mud wasp problem and it is standard procedure to leave pitot covers on until just before departure.
2) An open (ie, not signed off) tech log entry is required showing that covers are installed.
3) It is permissible to do the walkaround with the covers still on and this does happen when you arrive early at the aircraft. On the Airbus, the pilot not flying the sector does the walkaround.
4) In our company, the tech log is checked by the Captain in front of the F/O, for being signed off with no open entries before authorising the final door to be closed. I imagine most other airlines would apply similar CRM procedures.
5) Our engineers will come to the cockpit with the covers and show them to us before signing off the covers as "removed" in the tech log.
6) The A330 has the item "Gear Pins and Covers - Removed" as a challenge-response in the Before Start Checklist.
7) Yes on the Airbus there is a "100 knots" call during the takeoff roll as an airspeed crosscheck. The response from the flying pilot is "Checked".
8) The ADR 1+2+3 Fault is inhibited between 80 knots and liftoff.

I have absolutely no idea why they actually got airborne. I would've thought it would have registered this fault before the 80 knots inhibition phase. In any case, they can't possibly have got to 100 knots without an airspeed discrepancy (ie, not increasing from what it was at the start of the takeoff roll)!

Last edited by DutchRoll; 26th Jul 2018 at 06:58.
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Old 26th Jul 2018, 05:26
  #84 (permalink)  
 
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In the event the pitot covers were left on there was no airspeed discrepancy between all three indicators at all, they were all equally inaccurate!

Similar to the A330 stall warning logic being inhibited below 60kts, as it isn't possible to be airborne with <60kts IAS is it? AF447 proved that was faulty logic.

Recently we had a partial loss of airspeed event at ~120kts on the FO side (PF) from a very large insect impact totally blocking the pitot tube. The crew flew the OPT attitude and TO thrust until they could get the performance data and then flew loss of airspeed attitude & thrust settings for a happy ending. Perhaps the crew in this event did a similar thing?

Which leads to the future of fully automated aircraft, how would an fully automated aircraft deal with these sorts of scenario's?
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Old 26th Jul 2018, 05:52
  #85 (permalink)  
 
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Yeah but “airspeed discrepancy” also includes barreling down the runway with speed indications still the same as when you were parked at the gate! They can’t possibly have had an airspeed increase with the covers on.
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Old 26th Jul 2018, 06:07
  #86 (permalink)  
 
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Originally Posted by DutchRoll View Post
Yeah but “airspeed discrepancy” also includes barreling down the runway with speed indications still the same as when you were parked at the gate! They can’t possibly have had an airspeed increase with the covers on.
Agreed, I probably should have included a /sarc tag in there...
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Old 26th Jul 2018, 06:33
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Pitot covers installed are made of fabric so they don’t melt if pitot heat comes on with them installed. This fabric let’s a small amount of air through like a very dense filter. It’s possible airspeed did register up to a certain point as there would still have been some pressure getting to the probe.
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Old 26th Jul 2018, 07:05
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Hmmm..... modern pitot covers are heat resistant. But they’re not designed to let anything through.
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Old 26th Jul 2018, 07:26
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Originally Posted by DutchRoll View Post
Hmmm..... modern pitot covers are heat resistant. But they’re not designed to let anything through.
go and blow through one, I think you will be disappointed
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Old 26th Jul 2018, 08:25
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Which leads to the future of fully automated aircraft, how would an fully automated aircraft deal with these sorts of scenario's?
Any full automation worth it's salt would have done a 'reasonableness' check on airspeed (e.g. cross compared with ground speed changes) and aborted the takeoff by 80 knots.
It may surprise you, but the engineers who design this stuff are not idiots...
Bad air data is actually one of the easier design cases for full automation - there are multiple sources, cross compared with each other and GPS - determining which sensor(s) are wrong is usually fairly easy. Plugged Pitot ports are especially easily detected during takeoff since it messes so dramatically with airspeed. Plugged static ports are a much tougher problem since that won't change appreciably during a TO roll and would only become apparent once airborne.
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Old 26th Jul 2018, 09:27
  #91 (permalink)  
 
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Originally Posted by CurtainTwitcher View Post
In the event the pitot covers were left on there was no airspeed discrepancy between all three indicators at all, they were all equally inaccurate!

Similar to the A330 stall warning logic being inhibited below 60kts, as it isn't possible to be airborne with <60kts IAS is it? AF447 proved that was faulty logic.

Recently we had a partial loss of airspeed event at ~120kts on the FO side (PF) from a very large insect impact totally blocking the pitot tube. The crew flew the OPT attitude and TO thrust until they could get the performance data and then flew loss of airspeed attitude & thrust settings for a happy ending. Perhaps the crew in this event did a similar thing?

Which leads to the future of fully automated aircraft, how would an fully automated aircraft deal with these sorts of scenario's?
I'm guessing it wouldn't have you to get airborne to start with.
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Old 26th Jul 2018, 12:00
  #92 (permalink)  
 
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Originally Posted by A320skoda View Post


Pitot covers installed are made of fabric so they don’t melt if pitot heat comes on with them installed. This fabric let’s a small amount of air through like a very dense filter. It’s possible airspeed did register up to a certain point as there would still have been some pressure getting to the probe.

The Airbus pitot probe one's I had in my hand today weren't of a fabric variety. They were a made of of vinyl outer layer which was fully air/water resistant. I have seen fabric ones but they are of a fabric weave density that is similar to denim which would not let any significant airflow through to register any speed of a usable reference. There is picture at post 10 of the thread showing the covered probes from the actual incident.....they look pretty melted to me despite their supposed heat resistance.

Last edited by Tom Sawyer; 26th Jul 2018 at 12:31.
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Old 26th Jul 2018, 20:26
  #93 (permalink)  
 
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The railway engineers even 100 years ago had a statement " That if something can happen even a million to one it will happen"

So if the covers are so important to remove, as I know they are why not design them to ripe off at a certain air speed or design auto covers
which is not new as I have seen them on 1930s aircraft. Relying on humans to do such a critical operation is bound to fail, its a given.

So I think it is poor design knowing humans can fail.
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Old 26th Jul 2018, 20:35
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Originally Posted by horizon flyer View Post
The railway engineers even 100 years ago had a statement " That if something can happen even a million to one it will happen"
Murphy's Law predates the railways by several thousand years ...
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Old 27th Jul 2018, 01:23
  #95 (permalink)  
 
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Originally Posted by horizon flyer View Post
So if the covers are so important to remove, as I know they are why not design them to ripe off at a certain air speed or design auto covers
which is not new as I have seen them on 1930s aircraft. Relying on humans to do such a critical operation is bound to fail, its a given..
How about a pitot design change that enables them to be momentarily rotated 180 degrees and thus enable them to be self clearing? It could get rid of covers, mud-dobber nests, ice, insects.

Flyn.
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Old 27th Jul 2018, 03:17
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Originally Posted by flynerd View Post
How about a pitot design change that enables them to be momentarily rotated 180 degrees and thus enable them to be self clearing? It could get rid of covers, mud-dobber nests, ice, insects.

Flyn.
Because that type of design would allow the pitot to rotate in flight at some point, probably with a greater frequency that pitots become clogged, or covers are left on...

...............................

I am trying to find a way that our guys in the front got to rotate without noticing the discrepancy, is there a chance, at all, that the covers were already defective and allowed air in due to a break in the fabric, either before the flight or due to being pushed hard against the inlet and after rotating the relative airflow changed the position of the cover over the inlet and subsequently blocked the impact air..... I am very obviously clutching at straws, but it just seems so much more plausible than the idea of them not aborting the takeoff due to an airspeed discrepancy.
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Old 27th Jul 2018, 04:55
  #97 (permalink)  
 
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Welcome to the real world where Management do not want Engineers to carry out Arrivals & Pushbacks - utilising unskilled Ramp staff to do these tasks so the LAME can be used on other aircraft with defects - less LAME Engineers - unskilled cheaper Ramp staff - more bonus for Management!
All the Major Airlines are pushing more and more for this...Opens up the Swiss Cheese for more Human Error. Ask how many Pilots have had engineers on pushback & have rectified a defect that has occurred or advised the Tech Crew that it would be better to return to the gate & apply a deactivation procedure and MEL.
Most Majors all now use Maintenance Control remove advice which normally is under pressure (from management) to get the aircraft out....as a pilot, I prefer an engineer that I can talk too and is current/experienced on the type or who can see visually if I have a defect prior to getting airbourne...
Less Engineers on the Ramp is nothing but a Management Driven Bonus KPI...
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Old 27th Jul 2018, 09:09
  #98 (permalink)  
 
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A pool of hydraulic fluid was found at the holding point they departed from by the AOO
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Old 27th Jul 2018, 13:56
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Wellsaid, GDSlacker!
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Old 30th Jul 2018, 01:50
  #100 (permalink)  
 
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Originally Posted by DogDay2000 View Post
A pool of hydraulic fluid was found at the holding point they departed from by the AOO
Did the engineer forget to put the plug in too?
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