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Old 19th Dec 2013, 01:16
  #87 (permalink)  
Sarcs
 
Join Date: Apr 2007
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Leave it to the experts!

Jaba:
I strongly suggest you read the George Braly evidence provided to the SA coroner.
Yes it is a fascinating read and it was duly noted by the Coroner and ended up being the basis of his very damning findings into the actions, inactions/obfuscation in regards to the ATSB, CAsA and their involvement in the Whyalla crash investigation.

Couple of passages from the Whyalla Coroner's report :
12.80. Mr Braly outlined his opinions about the sequence of events leading to the ditching as follows:

'The following is a short summary of the sequence of events that, based on known hard engine operating data and the known objective findings surrounding the fatal crash, is what most likely happened in connection with this fatal crash:

1) The left engine crankshaft failed. The cause appears most likely to be related to improper installation of the connecting rod on the number six cylinder.

2) The pilot feathered the left engine and increased the manifold pressure on the remaining right hand engine from a normal 30" to some larger value in the 34 to 40" MP range. The pilot most likely failed to also increase the mixture on that engine to a suitably rich mixture.

3) The indicated airspeed (IAS) of the aircraft was reduced due to the left engine being feathered and the loss of nearly 50% of the previous available cruise power. The combination of the lowered cruise speed and the increased power on the right engine left the right engine in an environment very similar to a "climb condition". That is, the engine was enjoying minimal cooling air flow due to the reduced cruise speed and suffering from higher than normal power settings, both of which are typical of operating conditions encountered during routine climbs.

4) The crucial operational error was the likely failure of the pilot fully (or adequately) to increase the mixture on the right hand engine during this engine out cruise condition. Had the pilot simply and properly increased the mixture during this critical phase of the flight, as normal training and good engine operating practices would dictate, the right engine would not have failed and the aircraft would have, more likely than not, continued to a safe landing at Whyalla.

5) Something as simple as a small excess overhang of a helicoil tang at one of the spark plugs in cylinder 6 of the right engine could have dramatically increased the susceptibility of that cylinder to pre-ignition. The photographs in the ATSB report do not detail this area of the cylinders in sufficient detail to evaluate this not uncommon cause of pre-ignition.

6) One can readily demonstrate that even a newly built or overhauled TIO-540J2B engine, in perfect mechanical condition will, under the conditions described in paragraphs 2-4 above, operate in light to medium detonation and if left unresolved, that light to medium detonation will steadily raise the cylinder head temperature to the point that pre-ignition begins. After the pre-ignition begins, the engine will suffer catastrophic failure, usually within a matter of one to five minutes, unless the pre-ignition is promptly corrected. The author of these comments invites an appropriate representative of the ATSB to visit the author’s test facility and to observe the operation of the TIO-540J2B engine in any combination of power and mixture settings desired, in order to verify each and every observation about the operation of that engine described in these comments.

7) Notes:

a) The various different cruise mixture settings used by Whyalla and the other operators of these engines described in the ATSB report had no effect what so ever on this crash. At the reported normal cruise power settings, it is virtually impossible to cause one of these engines to detonate or pre-ignite, if the engine and the associated ignition system are in proper operating condition.
b) The climb mixture settings used by Whyalla (as distinguished from the descriptions of the power and mixture settings used by all other operators surveyed by the ATSB) were highly improper and likely caused one or more cylinders on both engines to frequently operate in light or medium detonation during portions of each climb.
c) The description of "deposits" on the pistons set forth in some detail in the report is essentially unrelated to any aspect of the cause of this crash. This extended pursuit of this subject is largely a red herring. For example, the deposits such as are described and displayed in the limited photographs in the ATSB report appear, from those photographs, in actuality, to be rather more accurately described as minimal as compared to most engines with similar operating time. In fact, they generally appear to be so minimal as to support the notion that the Whyalla engines were, in fact, frequently operating for short periods of time (probably during climbs, given the reported Whyalla engine operating technique during the climb phase of flight) in light to moderate detonation and this periodic condition actually cleaned the piston domes of some of the otherwise normal deposits. A better collection of photographs of the pistons and cylinder domes would provide still more accurate information on this subject.
d) In common pilot & mechanic operating terminology, when one "leans" the mixture, one reduces the ratio of fuel to air via use of the mixture control. However, when one thus "leans" the mixture to a condition that most pilots and mechanics would routinely call a "lean" mixture, the mixture remains a stoichiometric rich mixture. (The mixture is chemically a rich mixture until the exhaust gas temperature - - as indicated by the turbine inlet temperature gage [sic] during gradual reductions in fuel flow, - - has reached a maximum value and started to decline.) The confusing terminology in this area is responsible for an enormous misunderstanding in the pilot and mechanic community of the true implications of chemically rich and lean mixtures with respect to the operation of high powered piston aircraft engines. At one point, the ATSB report on this crash attempts to accurately define these terms, but then, in other areas, fails to accurately apply the correct terminology to the operation of the engines in question, and thus, compounds the confusion for pilots and mechanics who may read the report.

In its criticism of the routine use of so called "lean" mixtures, the ATSB fell into the common trap of mis-characterising stoichiometric "rich" mixtures as being "lean" mixtures. Worse, the lay press has grabbed onto this aspect of the report and has compounded the confusion in this area with published reports that completely mischaracterize the issue, blaming the crash on the use of "lean" mixtures, with an express or implied suggestion that the airline operators of this type aircraft were trying to skimp on fuel in order to save money at the expense of operating safety. (C196a, p4-6)

Some of Braly's findings etc (as stated above) were revised somewhat, after some of the assertions and conclusions made in the original ATSB final report were proved to be distorted and not entirely based on fact.... However the basic premise of Braly's review was largely applauded by the Coroner and enabled him to totally debunk the ATSB Final Report conclusions in regards to the reasons for the catastrophic double engine failures of VH-MZK.

Mr Braly's hypothesis for the causal chain from the time VH-MZK diverged right reads very similar to John Deakin's analysis article:
Reference pg 140 para 12.93:
'At the point where the aeroplane diverged right on page 3 at 1847:15, I think the pilot had been wrestling with problems with the right engine since some point in the climb. I believe at about that time he decided to simply throttle the engine. He could do that, and it’s my opinion that at that point in time he had experienced an episode of pre-ignition on the right engine. Whether or not it had already put a hole in the piston is debatable, but he did not, unlike the gentleman that was shown in the recreation of the data yesterday, the benefit of that sort of instrumentation and he would not have likely been able to stop the event before it did damage to the cylinder and, as indicated yesterday, once that sort of thing starts to happen in the cylinder, even if he throttled the engine, if you later reapply power, it’s going to happen again, assuming he had a hole in the piston already.

It is my opinion that the pilot decided simply to throttle the right engine and, in the process of that, the aeroplane yawed to the right slightly. In my experience teaching multi-engine pilots to fly during training, a momentary lapse in the heading control of the aircraft during major left/right power discrepancies is more common than not, even among good pilots, and I think the right-hand turn data is consistent with that, and a prompt re-correction back on course is consistent with him having done that and then retrimmed the aeroplane by use of the rudder trim control and what not to put the aeroplane back on course.

At that point in time the pilot had an unknown problem with the right engine, but it was still operating, and he had a 250- or 260-hour left-hand engine, and he made the decision to continue on. In the process he would have likely pushed up the power on the left-hand engine to something approaching climb power. He may have in fact used climb power - that would be a common training scenario for a multi-engine pilot, that if you lose an engine, you put the other engine up to climb power. That’s not necessarily the most optimal training exercise, but it’s a common method of teaching multi-engine pilots.

So I believe he increased the power on the left engine as he reduced the power on the right engine, and pressed on.

Some time just before 1901:10 when the MAYDAY was transmitted I think the crankshaft failed on the left engine. When the aircraft hit the water the left engine was feathered - I think the left engine would have virtually auto-feathered from the oil pressure loss. The right engine was still turning and not feathered, which is consistent with the previous power reduction.

I think if he had not already had a hole in the piston at the time - 1847:15 - when he throttled that engine, or when he tried to power up the right engine after the failure of the left, that he would have holed it promptly, because it would have gone back into pre-ignition.

It would have been a very confusing and difficult situation for the pilot.

They simply do not train for simultaneous engine failures, and they certainly do not do it at night with a full load of passengers over water.' (T3221-23)
Very sobering indeed...

There is no doubt the Coroner's report is a truly fascinating read (if you've got the time..), but the devil is always in the detail andwith most Coroner's reports that is contained in the findings and recommendations. In the case of Coroner Chivell his findings & recommendations underlined his frustration and consternation with the obvious bungling, obfuscation and disturbing shennanigans by the ATSB and to a lesser extent Fort Fumble. Perhaps this consternation is best illustrated from paragraph 15.5 (pg 181) to paragraph 15.13 (pg 183) {Note: Remembering that this was prior to the introduction of the TSI Act}.

Coroner report quote paragraph 15.10:
15.10. It follows, then, that I reject any suggestion that the ATSB were constrained or limited by section 19CA of the Air Navigation Act, 1920 in this investigation. In my opinion, the remarks of the Director of the ATSB, Mr Kym Bills, to the Australian Senate on 11 February 2003 reflect this misconception:

'For many years there have, from time to time, been difficult issues in some state and territory coronial inquests. The ATSB has been seeking better mutually cooperative relationships with coroners in the context of the legislation currently before the parliament and will continue to do so.

However, problems remain when the bureau is criticised at inquests for not spending more money on a particular investigation to satisfy
legal queries such as those relating to future civil litigation; when the high cost of inquests redirects our resources from higher safety priorities; where a particular inquest encounters difficulties with the Commonwealth no-blame legislation; under which we operate in accordance with international agreements; or where legal certainty is sought from an investigation, whereas the evidence often does not allow this and the ATSB’s focus is on the action necessary for future safety.'

The notion that ‘legal certainty’ (by which I assume Mr Bills means the finding of a fact to the requisite standard of proof) is somehow inconsistent with the ATSB’s role to ensure ‘future safety’ is not in accordance with logic. Surely an investigation must demonstrate, to an appropriate degree of certainty, that an incident has occurred in a particular way before remedial or preventative measures can be taken.
Hmm..interesting and what of the Coroner's well considered recommendations?? Have they been embraced by the regulator and promoted by the watchdog......well I'll let some one else be the judge of that...

IMO another (in a long line) of missed opportunities to advance our learning from a serious accident tragedy and to ultimately enhance aviation safety has been missed... As Gobbles quite often....said TICK..TOCK!
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