Aero Commander accident in the past - Reason for in-flight break-up.
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Aero Commander accident in the past - Reason for in-flight break-up.
The Aero Commander has an unmistakeable howling engine noise while climbing. I first heard, then saw, an Aero Commander climbing away from Essendon to the north-east this morning Monday 30 September. The weather over the Melbourne area was overcast with very strong gusting northerlies and the Aero Commander was making slow headway. Soon it would be over high terrain and although I haven't seen the flight forecast experience says it is probably moderate to severe turbulence below 10,000 ft over the ranges.
It got me thinking about the Aero Commander that broke up in mid-air on the same route as todays flight I saw. That was quite a few years ago and the circumstances leading to the in-flight break up could not be satisfactorily explained by ATSB. The sequence of break-up was explained after the wreckage was examined. Apparently there was no sign of structural failure that initiated the disaster. Whatever happened it was quite sudden and may have been caused by pilot input in turbulence. A radar picture revealed a series of sharp turns and loss of altitude before the break up started to occur. Hundreds of Aero Commanders and other general aviation light twins would have flown over the same route in the same conditions over many years yet none came to grief.
I wondered what really happened and no doubt many other people wondered the same thing. The ATSB report was, as usual, bland and gave no Most Probable Cause -other than a forensic examination of the break up sequence. I have always considered it a pity that ATSB are constrained by their legislation not to state a Most Probable Cause of an accident, if the facts cannot be proven with certainty.
I understand the American NTSB are required by law to give a Most Probable Cause if they are unable to pin down what actually happened to cause the accident sequence.
In the case of the Aero Commander crash in question, the pilot and her passenger were killed. Accidents involving in-flight control surface failures have often been caused by over-controlling by flight crew. The American Airlines A300 rudder fin failure was caused by over-controlling on the rudder by the first officer for example.
I wondered if over controlling by the Aero Commander pilot in severe turbulence - or even by her passenger somehow on the controls with her in fright - may have been a Most probable Cause? Something happened and few have talked about it...
It got me thinking about the Aero Commander that broke up in mid-air on the same route as todays flight I saw. That was quite a few years ago and the circumstances leading to the in-flight break up could not be satisfactorily explained by ATSB. The sequence of break-up was explained after the wreckage was examined. Apparently there was no sign of structural failure that initiated the disaster. Whatever happened it was quite sudden and may have been caused by pilot input in turbulence. A radar picture revealed a series of sharp turns and loss of altitude before the break up started to occur. Hundreds of Aero Commanders and other general aviation light twins would have flown over the same route in the same conditions over many years yet none came to grief.
I wondered what really happened and no doubt many other people wondered the same thing. The ATSB report was, as usual, bland and gave no Most Probable Cause -other than a forensic examination of the break up sequence. I have always considered it a pity that ATSB are constrained by their legislation not to state a Most Probable Cause of an accident, if the facts cannot be proven with certainty.
I understand the American NTSB are required by law to give a Most Probable Cause if they are unable to pin down what actually happened to cause the accident sequence.
In the case of the Aero Commander crash in question, the pilot and her passenger were killed. Accidents involving in-flight control surface failures have often been caused by over-controlling by flight crew. The American Airlines A300 rudder fin failure was caused by over-controlling on the rudder by the first officer for example.
I wondered if over controlling by the Aero Commander pilot in severe turbulence - or even by her passenger somehow on the controls with her in fright - may have been a Most probable Cause? Something happened and few have talked about it...
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Got a couple of good mates flying those aircraft for GAMS, that accident often crosses my mind. They are a great bunch of pilots & and good to work with on 'the other side.' I know they have procedures for turbulence but it must be on their minds as well.
It is fact Australia is a more litigious society than the US. Something to be proud of, NOT. What is the point of the ATSB if they can't state a probable cause? Could save quite a few million if it was disbanded.
It is fact Australia is a more litigious society than the US. Something to be proud of, NOT. What is the point of the ATSB if they can't state a probable cause? Could save quite a few million if it was disbanded.
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A similar one also without satisfactory explanation.
Investigation: 200400610 - Aero Commander 500-S, VH-LST
Investigation: 200400610 - Aero Commander 500-S, VH-LST
The Aero Commander has an unmistakeable howling engine noise while climbing.
DF.
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an aero engineer commented to me once that the combination of bends in the centre spar had been thought to cause about twice the stresses in the centre section as originally calculated.
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I could be wrong, but from memory, the Essendon crash involved an overloading of newspapers which was thought a a contributing factor.
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Unmistakeable yes, but I certainly wouldn't call it howling. Droning maybe, but not howling. I used to love hearing the sound of ACZ (the Augusta Airways mail plane) fading into the distance as it headed north every weekend on the (then) World's Longest Mail Run.
Sorry for the thread drift. Memory nostalgia overcame me.
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The meteorology of the 2007 case was examined in detail by one of my colleagues at Melb Uni with their student. The "executive summary" was presented at a local conference:
www.amos.org.au/documents/item/393
Gareth.
www.amos.org.au/documents/item/393
Gareth.
Interesting summary.
I'll remember [d^2ψˆ ( z ) ]/ dz^2 + m^2ψˆ ( z ) = 0 next time it's rough.
We'll never know if it was over controlling, or controlling and getting out of phase, or just the sheer force of what they went through.
I look back on what I took Shrikes through back in the day. It was years before this accident and Google so I had a deal of confidence (ignorant perhaps) in the airframe. With no radar, you'd look for the tops of the wet season CBs from a distance, dial 200 on the ADF to check, pick a heading, stick to that and wait till you were spat out the other side.
I'll remember [d^2ψˆ ( z ) ]/ dz^2 + m^2ψˆ ( z ) = 0 next time it's rough.
We'll never know if it was over controlling, or controlling and getting out of phase, or just the sheer force of what they went through.
I look back on what I took Shrikes through back in the day. It was years before this accident and Google so I had a deal of confidence (ignorant perhaps) in the airframe. With no radar, you'd look for the tops of the wet season CBs from a distance, dial 200 on the ADF to check, pick a heading, stick to that and wait till you were spat out the other side.
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The breakup most likely resulted from an encounter with localised and intense turbulence, or from an elevator control input, or from a combination of both.
Desert Flower, didn't you like the drone of the chieftain as it headed north every weekend as well? I enjoyed having a cuppa tea and biscuit in your donga after refuelling.
DF.
P.S. The "donga" now sits in my yard alongside the house. Still has all the memorabilia attached to the walls & hanging from the ceiling!
Last edited by Desert Flower; 30th Sep 2013 at 11:52.
Thread Starter
That do you Centaurus, from the ATSB report?
I was surprised that in the case of the 2007 Aero Commander accident, ATSB studiously avoided mentioning the possibility that, at the onset of severe turbulence over the hills in partial IMC, the passenger may have grabbed the controls in fright counteracting the pilot's input. On the other hand the passenger may have thought he could help the pilot with the controlling of the aircraft in severe turbulence? If indeed that was the case, things would literally have gone downhill from there.
Perhaps in their deliberations, investigators should make mention in some detail what actions by the pilot could be discounted. By not doing so, it leaves the situation wide open to healthy speculation just as I am doing right now. After all, ATSB alluded to possible over-controlling of the elevators. But not by whom
Last edited by Centaurus; 30th Sep 2013 at 13:32.
I flew the man many times, and never once did he touch - or appear to want to touch - any control.
Last edited by compressor stall; 30th Sep 2013 at 13:26.
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I flew the man many times, and never once did he touch - or appear to want to touch - any control.
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This has been discussed at length in numerous threads all of which are merged, but:
It's worth noting that the passenger was the foremost expert on Aerocommanders in the southern hemisphere (if not the world), and the pilot was one of the more experienced on the line at the time. At 7,000ft the aircraft is nestled right into a reasonable turbulence penetration speed at cruise settings.
With the experience onboard, a low time airframe (one of the best in the fleet) and the aircraft comfortably in its niche, you could all but rule out over manipulation.
The only freight onboard was tools and parts for repairs to another aircraft.
Anecdotally, in the past 6 years I can think of at least 5 CB penetrations by Aerocommanders, that the pilots and aircraft have come away from relatively unscathed.
It's worth noting that the passenger was the foremost expert on Aerocommanders in the southern hemisphere (if not the world), and the pilot was one of the more experienced on the line at the time. At 7,000ft the aircraft is nestled right into a reasonable turbulence penetration speed at cruise settings.
With the experience onboard, a low time airframe (one of the best in the fleet) and the aircraft comfortably in its niche, you could all but rule out over manipulation.
The only freight onboard was tools and parts for repairs to another aircraft.
Anecdotally, in the past 6 years I can think of at least 5 CB penetrations by Aerocommanders, that the pilots and aircraft have come away from relatively unscathed.
Last edited by avconnection; 30th Sep 2013 at 13:56.
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, it leaves the situation wide open to healthy speculation just as I am doing right now. After all, ATSB alluded to possible over-controlling of the elevators. But not by whom
Last edited by prospector; 30th Sep 2013 at 20:38.
an aero engineer commented to me once that the combination of bends in the centre spar had been thought to cause about twice the stresses in the centre section as originally calculated.
That could probably do with some elaboration from an aeronautical engineer
knowledgeable about stressing and the loadings that occur in different flight modes. Makes you wonder whether ATSB ever consult any real boffins?
re.. .. 'Healthy speculation' . . . . . aren't you being a bit harsh there on Centaurus, Prospector ?. Pre report speculation is often ludicrous, true, but post report, and in the analysis of deficiencies in reports. . . . it's a friggin' minefield, mate. Especially when the men sent out to do the forensic don't know a tapered spiggot from a knurled flange bracket.
Last edited by Fantome; 30th Sep 2013 at 21:03.