Could the Australian Transport Safety Bureau’s final report on the crash of the Piper Chieftain into the sea off Whyalla in May 2000 have inadvertently overlooked some potentially very relevant matters?
The Australian Transport Safety Bureau’s decision to release its Whyalla Airlines crash investigation report on December 19, 2001, was promptly branded by industry cynics as a Canberra ruse to bury the report and any resulting debate in the festive period, in the hope that it would be stale news when post-Christmas normalcy returned.
Seven passengers and the pilot died when the Piper Chieftain was ditched at sea at night following a double engine failure on May 31, 2000. The airline voluntarily suspended operations the following day in the hope of an early return to the air. But Whyalla airlines never flew again.
In a post-accident pattern of behaviour now familiar to the general aviation industry, the Civil Aviation Safety Authority (CASA) launched a series of post-accident “special audits,” interviewing various individuals including a former chief pilot (who had been dismissed six weeks earlier for alleged misconduct not related to his aviation duties); the chief pilot of another operator; and the bereaved partner of the deceased pilot.
The then chief pilot and manager, Kym Brougham, recounted that the statements of these individuals were preferred by CASA above the detailed information offered by a long term employee:- “A mature, adult, sensible person, who was ignored because he answered the questions too well, and was accused of being coached to answer them.”
The CASA investigation quickly homed in on “evidence to suggest” that pilot flight and duty time records had not been properly maintained – “leading to the risk of incorrectly calculating the statutory rest periods.” To date, CASA has not released the outcome of its investigations into these allegations; and the ATSB findings did not suggest that fatigue issues were a factor.
CASA then called in extra staff from Canberra, says Brougham: “They kept saying ‘we need more time to look at it,’ meaning to look at whatever allegations were made against us. On June 10, on the day of the memorial service at the beach, they served a “suspension notice pending investigation.” The notice, signed by (then) Assistant Director Aviation Safety Compliance Division, Laurie Foley, said the suspension was based on “reason to believe that there exist facts and circumstances which justify the suspension.” Quoting no demonstrable facts and circumstances to support the suspension, CASA used language such as:
- “It therefore appears that…….. some of the records of the duty times of the members of the operating crews …..may be inaccurate”;
- ”It appears that, on some occasions…….dead head transportation of pilots was not taken into account when calculating flight and duty times”;
- “Some…..pilots interviewed by the Authority consider the “turnaround” between two sectors on your regular public transport routes may be inadequate”;
- “Some of the pilots …….. expressed concerns about the adequacy of the accommodation provided”;
- There is evidence to suggest that the company’s pilots are under undue pressure to comply with time constraints imposed by the company; may not be recent to conduct the operations required of them; and the company is not providing adequate rest facilities.
- On the basis of the facts and circumstances described above, I have reason to believe that there is a serious risk to air safety if the AOC…….were not suspended;”
- Therefore, until these facts and circumstances can be investigated thoroughly and such further action as may be appropriate may be taken by CASA, I have reason to be believe that to permit the continued operations of the company would pose a potentially serious and immediate safety threat to other aircraft, and to such persons and property as may be effected by the operation of aircraft under the control of Whyalla Airlines Pty Ltd
CASA did not provide the company at any time with details of the progress of the investigation; nor any with indication of a time when its conclusion was expected. This mirrors the authority’s conduct in similar investigations such as those related to the suspensions of Aquaflight Airways, Uzu Air, and Yanda Airlines.
“We cooperated with them all through June and early July, but it looked like they weren’t going to relent. They kept saying ‘we need more time.’ We were desperate at that stage to create some flying and some cash flow, and finally we went to the AAT (Administrative Appeals Tribunal) to appeal against the suspension. In the third week in July they got the sitting under way, but CASA weren’t ready to start until the following day because the expensive QC they’d hired hadn’t yet done any homework. In fact, at one stage he fell asleep while he was cross-examining his own witness. CASA didn’t care, because they knew the longer they dragged it out the more they’d hurt us.”
In the AAT, under its in-house rules which are more relaxed than those of formal courts, a number of allegations and unsigned statements became public property and were duly miss-reported in the non-aviation media, says Brougham: “Anything tendered in the AAT was available to the media. That means that CASA can make a wild allegation, and the media can print it like it can print evidence given under oath in a normal court case. The media had taken an above-average interest, and CASA circulated these documents, some of which were unsigned witness statements. The pilots wouldn’t sign them, because they said they were bullshit, but the media printed them as evidence, and people read terrible stories about us.” (One television report interpreted the ATSB findings interestingly, saying: “The ATSB said the company had been trying to save money by using a weak mixture of fuel!”)
As well, CASA indicated in the AAT hearings that if the tribunal overturned its decision to suspend the company’s AOC, it would probably then suspend or cancel Broughham’s chief pilot approval, which would have the effect of a further suspension or cancellation of the AOC, and a return to the AAT for a further confrontation with CASA’s expensive legal firepower. Assessing that further AAT hearings would send them insolvent, Kym and Chris Brougham voluntarily surrendered their suspended AOC.
Meanwhile both had provided full cooperation to the ATSB, but they and many of their staff were unimpressed with the level of technical knowledge displayed by some of the investigators, whom they say appeared to have decided that incorrect fuel mixture leaning practices were a key factor in both engine failures: “I finished up asking them technical questions about operating engines, and I found their knowledge deficient,” says Brougham. “We spent two weeks researching and drafting the reply, getting the facts right, but that’s how far off track they were; they just wouldn’t talk to us.”
In its draft report (which was leaked to the media), the ATSB focused strongly on the use of excessively lean fuel mixture as the cause of both engine failures, says Brougham: “That was when a lot of people turned against us, because we were blamed for running the engines too lean to save money, and for causing the accident. The draft report actually said the chief pilot was more interested in saving money than in his safety program. The ATSB report finally vindicated us, but by then it was too late.”
The final report release date, advised to interested parties when the ATSB’s draft report was circulated to them in April 2001, was set before significant new evidence was thrust under the ATSB’s nose, which compelled a complete review of the investigation, and a comprehensive rewrite of its conclusions. The disparities between the preliminary and final reports raise serious questions about the quality of the ATSB investigation, as well as CASA’s role in the airline’s shutdown. The report also raises more questions than it answers, about other possible and credible causes of both mechanical failures. The removed material related to the mixture leaning issue was not replaced by other analysis, leaving notable apparent gaps, omissions and errors in the final report.
Under “Significant Factors” in the draft report, the ATSB said the Manager/Chief Pilot had instructed pilots to use fuel mixture leaning procedures that did not provide an adequate margin for error from exceeding fuel mixture leaning limitations; and that these practices had resulted in unintentional mechanical damage, which had resulted in the two engine failure, even though they were of dissimilar types.
Normal mixture leaning procedures in high-performance piston engines are to lean the mixture until the exhaust gas temperature (EGT) reaches a peak; and then to richen the mixture until the EGT drops by 25 to 50 degrees according to engine manufacturer recommendations. Some aircraft manufactures publish alternative procedures, usually not supported by the engine manufacturer, under which the mixture may be further leaned until the EGT reduces to a similar degree. Although the draft report claimed those practices had been extant at Whyalla Airlines, the final report made no such claim; and noted: “The Chieftain engine handling procedures described by most pilots were generally in accordance with those described by the Manager. Most pilots used a mixture setting in cruise that resulted in an EGT 50°F rich of peak.”
Repeatedly throughout the draft report, the ATSB made statements in support of its mixture leaning theory, saying that specialty analysis had found the damage in both engines to be consistent with the effects of abnormal combustion; that it had found the airline’s management policy had been to encourage fuel leaning practices which had the unintended consequences of inducing engine damage; that reports from various sources suggested that the actions of the pilot might have been adversely influenced by the manager; that no company pilot, including the Manager/Chief Pilot, expressed any knowledge of the engine manufacturer’s recommendations; that new pilots were being taught to operate the engines on the lean side of peak EGT as part of a normal cruise power regime; and that the chief pilot’s continual advocacy of minimising fuel consumption was likely to have encouraged a culture within the company that operating the engines within reduced fuel leaning margins was the norm.”
Labelling several of these and other statements in the report as “ill founded and defamatory,” Whyalla executives Chris and Alan Brougham sent the ATSB a 17-page analysis of the draft and successfully demanded their removal as well as raising several apparently relevant new issues which the investigation had not addressed.
They later provided a more detailed and technical analysis of some of the draft’s findings, prepared by Doug Sprigg, a powerplant mechanic and commercial pilot who has spent 30 years studying engine reliability, failure causes, and the development of strategies to extend engine longevity. This analysis posed the serious possibility that the ATSB had developed a tunnel-vision view of its “aggressive leaning” theory, which had caused it to overlook available information of high potential relevance. While ATSB postulated that the left engine’s bearing failure was caused by combustion abnormalities creating high combustion chamber pressures and resulting high loads on the engine’s reciprocating components, Sprigg’ analysis rejected this on what other engine specialists agreed were credible technical grounds. He believed that there was ample evidence that faulty bearing manufacture had caused a large number of bearing failures in similar engines; and that this was an issue which ATSB had not investigated adequately. Sprigg’s analysis also credibly questioned a number of ATSB conclusions relating to the nature and cause of the evidence of pre-ignition identified by ATSB, and its role in the engine failures.
Two current issues in the USA and failures of a number of factory remanufactured engines in Australia supported Sprigg’ view that this issue must be evaluated in the Whyalla context. A large number of engine bearing failures in high-compression Textron Lycoming powerplants had now caused the grounding of a fleet of new turbocharged Cessna 206Ts in California, and given rise to a class action against Textron Lycoming and New Piper by Malibu Mirage owners. Sprigg believed these had occurred as a result of changes in the metallurgical composition of the bearings themselves.
The Californian Highway Patrol had taken delivery of 14 of an order of C206Ts, and had already introduced 12 into service, when it grounded the entire fleet following a series of forced landings due to bearing failures in aircraft which had all flown less than 500 hours since new. Bearing failures had also triggered a class action by Piper Malibu Mirage owners against Textron Lycoming and New Piper; and court documents provided copious evidence that Piper, Textron Lycoming and bearing manufacturer KS Bearings Inc were well aware of the problem, and had been working on remedies for at least two years.
ATSB Executive Director Kym Bills however said: “Based on careful analysis of the engine failures and recorded radar and audio data, it is likely that the left engine failed first as a result of a fatigue crack in the crankshaft. This was initiated about 50 flights before the accident flight due to the breakdown of a connecting rod bearing insert. The combined effects of high combustion gas pressures developed as a result of deposit-induced pre-ignition, and lowered bearing insert retention forces due to an ‘anti-galling’ lubricating compound used during engine assembly by the manufacturer, led to this breakdown.
“It is likely that because of the increased power demanded of the right engine after the left engine failed, abnormal combustion (detonation) occurred and rapidly raised the temperature of the pistons and cylinder heads. As a result, a hole melted in the number 6 piston causing loss of engine power and erratic engine operation.”
Although issues were identified in the company that the ATSB believes had the potential to adversely influence safety, the report says: “There was insufficient information to conclude that any of these issues were of significance with respect to the accident.” The Bureau had stated publicly that: “No one should be blamed for this accident.”
In its technical analyses, Sprigg insisted that ATSB was probably wrong on several counts: “I dispute that cracking was initiated fifty flights before the loss of the aircraft. That would mean the engine ran for fifty flights with a de-metalled big end bearing that had excessive clearance and a lack of lubrication, which had already caused a “planar discontinuity”, cracking of the nitrided surface of shaft. I believe the fatigue crack propagation would have to be far more rapid, associated with first order vibrations in the shaft, causing almost immediate failure after the initial heat stress crack. How can a journal or a connecting rod bearing last without lubrication, cooling and cushioning for fifty flight cycles after lubrication breakdown has already caused heat stress cracking? ”Fifty (fatigue) cycles leading to ultimate failure of the shaft would be likely to be related to first order disturbance (power stroke forces) in the shaft, and not flight cycles, which are far more likely to show up in turbine engines during rapid temperature changes. If the fatigue crack propagation were related to flight cycles, then it is more likely that the planar discontinuity was caused by heat stress of the nitrided crankshaft surface during re-grinding as part of the engine remanufacture process 200 hours before.”
Similarly Sprigg contested ATSB conclusions that the left engine failed because of pre-ignition-inducing deposits in the combustion chamber which melted and created regions of incandescence that led to pre-ignition and increased bearing loads: “Advanced ignition timing caused by preignition, should show increased heat flow to combustion chamber surfaces. That would be manifested in melting damage to piston crown, top ring land and/or cylinder head, before any damage could be attributed to this cause in the connecting rod assemblies. Massive pre-ignition detonation could cause bearing failure, but combustion chamber surfaces should have evidence of overheat and or overload.”
Sprigg also did not accept it was possible that the right engine was operated under different conditions to the left engine until the failure of the left engine: “That is, had there not been the catastrophic failure of the left engine, both engines would have had the same piston crown deposits. I strongly believe differences are due to the high power operation of the right engine to maintain flight after the failure of the left engine. Examination of failures in engines of similar type revealed similar piston crown deposits, because they are normal combustion products. Again we are looking at a sudden and unforseen, catastrophic bearing failure which may be due to babbit material (bearing overlay) fatigue.”
Both Brougham and Sprigg, independently say several other credible causes of the partial failure of the right engine have not been duly investigated or eliminated:
- a misfiring magneto
- a blocked injector
- a faulty fuel control unit or
- the pilot omitting to adjust the mixture from its lean cruise power setting with the engine on climb power.
Brougham says “CASA claims the hole was recent, in the last ten minutes of flight, because it would otherwise have dumped all the oil. We say that’s nonsense, because we’ve holed two pistons before and the flight has continued its whole duration. So we know they’ll run for another hour with a hole that size in the piston.”
The ATSB made recommendations to Textron Lycoming and the FAA on engine deposits that may cause pre-ignition; and on the use of anti-galling compounds between connecting rod bearing inserts and housings during engine assembly. It had however apparently not sought to explore the relevance to the Whyalla events, of the unusually large number of bearing failures in similar powerplants in the US and Australia.
- A convincing and informative review of these events by US aviation commentator John Deakin presents a lucid and knowledgeable countervailing view that is well worth reading.
- This article has been only slightly updated and is re-published with the kind consent of Yaffa Publishing’s Aircraft & Aerospace magazine where it first appeared in March 2002
- Submission to Aviation Safety Regulation Review ProAviation, updated February 21, 2014 Index We havn't been able to make the automated index function work in this post. Following are the principal headings in the correct sequence. We're working on a fix for that. Meanwhile the ten case studies which were part…
- A chain of events that competent, responsive and honest management could clearly have prevented, ended in the grounding of about 65% of Australia's general aviation fleet in December 1999; most of them for almost four months. In-house Civil Aviation Safety Authority documents show that CASA ignored important industry input and…
- The Aerial Agricultural Association of Australia (AAAA) has added its voice to the torrent of industry grievance against the aviation regulator. AAAA’s blistering submission to the Aviation Safety Regulation Review (ASRR) Panel is all the more notable because the Association had always cultivated a track record of positive engagement with…
- Posted by: Paul Phelan Posted date: October 31, 2012 | comment : 2 On October 22 this year a Senate Committee inquiry into accident investigation processes began hearing submissions that focused on the relationships and interactions between the Civil Aviation Safety Authority and the Australian Transport Safety Bureau, and on the management of their investigations…
- Regulation of Australian General Aviation and Low Capacity Airline Transport Volume 1: Enforcement - Why is it failing? Paul D Phelan September, 2000 The original version of this analysis was circulated electronically to all members of Federal Parliament, industry identities, aviation writers, other selected media outlets, industry associations, CASA Board…