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King Air down at Essendon?

Old 24th Sep 2018, 09:03
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And, you will also read about simulator trials where the aircraft was taken off, with full NL rudder trim, and how difficult this was for the pilot to sustain.
Actually the report says:

" The yaw on take-off was manageable......After takeoff the aircraft was manageable but challenging up to about 140 knots..."

The aircraft didn't get above about 112 kt. So, on the ATSB's own evidence, the yaw from full LH rudder trim was manageable.
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Old 24th Sep 2018, 09:07
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I won't say that this report is the biggest load of cr@p I've ever read from the ATSB as practically everything they have written in the last 30 years or so is cr@p and the good old rubber stamp "Pilot Error" comes out again. They have obviously not consulted professional King Air pilots. I'm appalled once again.
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Old 24th Sep 2018, 09:10
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Question from a pilot not rated on the King Air.

What is the scenario that the trim would be left in this position from a previous flight?
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Old 24th Sep 2018, 09:36
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Old Akro,

I don't believe you are reading the report as closely as you could, re the simulator trials. The pilot doing the trials said that leg muscle forces "could only be held for a short period of time". And obviously, the strength, fitness and age of the pilot would be a factor in exactly what the period of time was, and to which airspeed things could be managed.

The simulator performance in this situation would not be an exact replication of the real aircraft. Did the simulation have the same CG as the accident aircraft? It doesn't say, but that aspect would have a bearing on the controllability.
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Old 24th Sep 2018, 09:49
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Originally Posted by FGD135
Groggy, read the report. Full explanation there as to how the rudder trim could not have been "displaced by impact forces" (e.g. the position of the jackscrew).

And, you will also read about simulator trials where the aircraft was taken off, with full NL rudder trim, and how difficult this was for the pilot to sustain.
FGD,

With respect I take your point about the trim jack but please consider that if trim wasnít checked then maybe the power lever friction nuts werenít checked either. I could live with that scenario where both items were missed and Murphy took over with full left rudder trim and a rollback on left engine which would have resulted in a very very difficult situation. My reason is it should have climbed!!!!

Groggy
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Old 24th Sep 2018, 09:54
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Somebody asked why, with both engines supplying full power, the aircraft couldn't still climb.

I believe the answer to this is because the drag was too great. With the pilot's "leg having given out", re the simulator trials, the aircraft's sideslip would have increased to the point where the yaw moment due rudder was equal to the opposite yaw moment due fuselage angle. As shown in the report, that was a significant angle, presenting much more of the airframe and nacelles to the airflow than is normally the case.

Also, with the sideslip angle at around 30 degrees, the prop thrust is acting at this angle, rather than directly along the flight path, so the reduction in thrust, also considering the off-optimum incidence angle into the props, could be anything up to 50% (my estimation).
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Old 24th Sep 2018, 09:55
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I don't believe you are reading the report as closely as you could
I read those comments as relating to the 140KT condition. They are written after the concept of loss of control at 140 Kt is introduced. Earlier in the reference when rotation and initial lift off speed were discussed the forces were labelled as " manageable".

Frankly, think there is a big question about the relevancy of 140 Kt. The best rate climb speed is 121 Kt. Surely, there is no need (in an emergency situation) to go faster.

And if the simulator was not relevant and the loading not able to be represented, then what on earth was the ATSB doing it for??
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Old 24th Sep 2018, 09:57
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Hey Groggy, I think the ATSB did a good job ruling out the "power lever migration" theory. The witness marks in the roof of the building, the prop damage and the audio recording all showed that both engines were at full power.
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Old 24th Sep 2018, 10:01
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Somebody asked why, with both engines supplying full power, the aircraft couldn't still climb
FGD

1. The whole Essendon incident occurred in 12 seconds. a) I don't think that fits with the meaning that the SIM pilot was meaning when he said "your leg WILL give out...." and b) as noted above, I believe this refers to the 140 Kt condition. I don't believe this refers to the 100 - 112 kt (ish) speeds of this flight. I think the SIM pilots comment " The yaw on take-off was manageable" refers to this flight condition.

Secondly, the ATSB side slip angle calculation and hypothesis is seriously flawed.
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Old 24th Sep 2018, 10:04
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Originally Posted by FGD135
Hey Groggy, I think the ATSB did a good job ruling out the "power lever migration" theory. The witness marks in the roof of the building, the prop damage and the audio recording all showed that both engines were at full power.
FGD,

Yes saw that however donít forget that a windmilling constant speed propeller would have considerable force spinnnng at 2000 rpm.

Groggy
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Old 24th Sep 2018, 10:07
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Old Akro,

What was flawed about their sideslip angle calculation? The relative positions of the impact marks on the roof would make for a pretty accurate calculation. I didn't look too closely at their photographic pixel method, but the impact marks were pretty definitive.
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Old 24th Sep 2018, 10:08
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Old Akro,
as you are asking lot of questions and providing no answers:
why did the PIC broadcast 7 maydays? Wouldnít his attention not be better utilised by flying the aircraft? Who, apart from those on the aircraft , were going to help him with his predicament?
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Old 24th Sep 2018, 10:09
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Groggy,

Yes, but a big big difference in the blade angle and resultant damage signature to a prop that is windmilling compared to one that is delivering power.
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Old 24th Sep 2018, 10:09
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Itís a good report in my view (apart from the odd spelling mistake). Full left trim not detected prior to take off. Possible confusion and mistake that engine had failed.

But why was full left trim set in the first place? Three complete rotations were needed. Who would have done that? Why would they have done that?

It wasnt maintenance as the aircraft had flown after its last maintenance.

So what was it?
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Old 24th Sep 2018, 10:31
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FGD: You keep talking about ‘sideslip’.

Wouldn’t an uncorrected rudder trim cause a ‘skid’?
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Old 24th Sep 2018, 10:38
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why did the PIC broadcast 7 maydays?
Wombat, seriously? The report says that the pilot made 1 Mayday transmission in witch he repeated Mayday 7 times. A perfectly human response to an extreme situation I would have thought.
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Old 24th Sep 2018, 10:41
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Leady, slip and skid occur during a turn, when the turn is not perfectly coordinated.

Sideslip is when the aircraft is going through the air "somewhat sideways". It can have a significant sideslip angle but still be travelling in a straight line - with zero yaw and all forces in equilibrium!
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Old 24th Sep 2018, 10:43
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Akro - it didn't climb because he stopped piloting. Fly the aircraft first and worry about mayday mayday mayday later.

Wombat, seriously? The report says that the pilot made 1 Mayday transmission in witch he repeated Mayday 7 times. A perfectly human response to an extreme situation I would have thought. Maybe so AKRO - but NOT a perfect response by a well trained pilot who is taught to fly the bloody aeroplane. Next time I'm a passenger I hope I don't have a pilot who gives your definition of a perfect response to an anomoly. I know you're trying hard to defend a buddy here, but to say that screaming Mayday 7 times while his machine NEEDS flying is an expected and understandable response really is a stupid thing to say.

As for the Pilots leg giving out holding against the rudder trim - how long was it airborne for again?? Seconds wasnt it?? I doubt the leg gave out.
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Old 24th Sep 2018, 10:44
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I didn't look too closely at their photographic pixel method
Look closely at the pixel method. Its responsible for 5 out of 6 calculations. Think about the potential errors and the area of uncertainty that that creates. Think about the parallax that they are using to determine yaw vs direction of travel.
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Old 24th Sep 2018, 10:46
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Originally Posted by Old Akro
Wombat, seriously? The report says that the pilot made 1 Mayday transmission in witch he repeated Mayday 7 times. A perfectly human response to an extreme situation I would have thought.

aviate, navigate,communicate?
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