Rex incident YSSY
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The Australian article says the Rex aircraft was 26 years old - am I correct in saying the part that failed could have been only, say 10 years old - engines hours, or age surely can be vastly different to airframe hours or age. If a new engine fails on an older airframe and an accident ensures, the airframes age surely can't be the cause of the accident?
The Australian article says the Rex aircraft was 26 years old - am I correct in saying the part that failed could have been only, say 10 years old - engines hours, or age surely can be vastly different to airframe hours or age. If a new engine fails on an older airframe and an accident ensures, the airframes age surely can't be the cause of the accident?
Paul Cleary seems to have perfected the journalistic version of the double-tap; you get two stories based on essentially the same "facts" (and I use that word advisedly) undr different headlines in rapid succession. How Rex pilots narrowly avoided disaster after plane lost propeller and Engine crisis as REX propeller dropped is just one example; he follows the same approach with stories on in-flight wi fi and Sydney Airport's CEO.
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For starters, the accident airplane, VH-NRX, is 25 years (and one month and seven days) old; not 26 years old as claimed in the article. NRX is Saab 340B serial number 291 - its first flight was 25 February 1992 and it entered commercial service with the US regional operator, Business Express Airlines, a month later on 25 March 1992.
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If the failed shaft in fact ran 30K hrs with that fault, I might expect a special inspection (ultrasonic?) on high-time hardware in the fleet. It perhaps could even be done on-wing overnight.
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And strange as it might seem, the PGB supports the core engine in space within the nacelle; consider that the major mount loads are imposed by the prop torque, which are directly reacted by the PGB connected to the nacelle. I believe this is true of many other turboprop installations as well.
I've been following this thread as best as I could, so apologies if I'm repeating someone's comment.
The flange above, which is connected to the driveshaft, is obviously the main focus of attention, so it's not surprising it was removed for safe keeping prior to prop transportation.
As for The Australian article:
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
The flange above, which is connected to the driveshaft, is obviously the main focus of attention, so it's not surprising it was removed for safe keeping prior to prop transportation.
As for The Australian article:
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
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. . .As for The Australian article:
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
Not so much in this external portion of the fan shaft, exposed full time to ambient airflow.
True in a way, but in fact the PGB is married to the core engine in the shop, and the full powerplant is then hung in the aircraft.
Byron Bailey, is this Ian Bailey??
. . .As for The Australian article:
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
The gearbox overheating and causing the gearbox to seize sounds very feasible to me. Maybe the gearbox overheated because of a lack of oil, or maybe because of a design weakness. If the SAAB gearboxes often overheat, then this would be a reasonable line of investigation to follow.
The only time this has ever happened in the last 30 years of SAAB operations it was the result of a metallurgical manufacturing defect in the shaft. To assume the cause is anything different at this stage is a gamble most "experts" would not be willing to take.
Last edited by Slippery_Pete; 4th Apr 2017 at 13:23.
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Although it was probably authored by a PR flak, there is an interesting rebuttal of Bailey's statements by Rex's John Sharp in Friday's "Australian". Unfortunately the article is behind an online paywall so I'm not posting the link but if you have a sub or the paper itself it's worth a look.
Although it was probably authored by a PR flak, there is an interesting rebuttal of Bailey's statements by Rex's John Sharp in Friday's "Australian". Unfortunately the article is behind an online paywall so I'm not posting the link but if you have a sub or the paper itself it's worth a look.
Passengers, industry full of praise for Rex crew after mishaps
JOHN SHARP The Australian 12:00AM April 7, 2017
I have been associated with Regional Express (Rex) since its launch in 2004 and would like to respond to some of the claims made in this section last week.
Rex has an excellent safety record, having flown a million hours without a single flight-related injury. Rex’s aircraft are much more reliable than all other regional operations of the major carriers in Australia. This is demonstrated in its on-time performance being the best for more than a decade.
Further, with proper maintenance, age is not a root cause for safety incidents. The only other recorded similar event to that of Flight ZL768 (when the propeller separated) was in 1991, when US carrier Comair’s aircraft also landed safely after a separation of its propeller. The Comair aircraft was only two years old. Similarly, the Qantas A380 involved in a near catastrophic accident in 2010 was only two years old.
In last week’s article, (‘‘Rex pilots narrowly avoided air disaster’’, 31/3), Byron Bailey said “the pilots took quick action to shut down an overheating engine”. Mr Bailey said the crew was shutting down the engine because gearbox problems were causing the temperature to rise.
Rex can confirm the engine was not overheating at any stage. Nor was its gearbox its “weak link”, as Mr Bailey said. This allegation is the view of an individual who is not a subject matter expert. There are no statistics to support such a view.
The allegation about the engine overcoming the drag inside the gearbox is also a figment of imagination. The General Electric engine fitted to the Saab 340 is a free power turbine and, as such, the engine and gearbox have no mechanical connection.
Further, I challenge Mr Bailey’s statement that, had the pilots not taken action to shut it down, the propeller would have “been spinning faster and it could have impacted the fuselage”. This allegation is emotive and unfounded. The propeller separated only when the first officer selected fuel off, which also feathers the propeller.
We wish to set the record straight on allegations on the industrial relations with the crew. Rex pilots are paid in accordance with an enterprise agreement and are rostered in accordance with Civil Aviation Order flight and duty time limitations. Overnight allowances have always been paid to Rex pilots in accordance with the EA.
Finally, Rex did not suffer three incidents during March. Rex experienced two unrelated events. The first was the propeller separation on Flight ZL768 on March 17. The second was engine failure on Flight ZL821 on March 23. In the third incident, the crew initiated an air return because they believed they could hear an air noise associated with the ground communications hatch. The flight did not have any other apparent issues. Engineers carried out a thorough inspection including ground runs and no fault was found. The aircraft returned to service.
In summary, every carrier in Australia and in the world suffers from similar safety events occasionally as this is an inevitable part of flying, no different from driving. What is important is the in-built redundancy of the aircraft, which allows safe operations despite component failures. These safety features have resulted in flying being much safer than driving in terms of injuries per kilometre travelled.
The Saab 340 is designed to be able to climb, cruise and land safely on only one of its two engines. This was demonstrated in the events cited in the article to the extent that many passengers said they did not feel any difference when the aircraft landed uneventfully after the propeller separation.
The other important contributor to flight safety is crew flying standards. The two events demonstrate the high quality of training of Rex crew such that normal landings are achieved even under rare and challenging circumstances. Rex has received universal praise from the aviation world for the calm, professional and effective actions of the crew after the separation of the propeller.
John Sharp is deputy chairman of Rex and a former federal transport minister.
JOHN SHARP The Australian 12:00AM April 7, 2017
I have been associated with Regional Express (Rex) since its launch in 2004 and would like to respond to some of the claims made in this section last week.
Rex has an excellent safety record, having flown a million hours without a single flight-related injury. Rex’s aircraft are much more reliable than all other regional operations of the major carriers in Australia. This is demonstrated in its on-time performance being the best for more than a decade.
Further, with proper maintenance, age is not a root cause for safety incidents. The only other recorded similar event to that of Flight ZL768 (when the propeller separated) was in 1991, when US carrier Comair’s aircraft also landed safely after a separation of its propeller. The Comair aircraft was only two years old. Similarly, the Qantas A380 involved in a near catastrophic accident in 2010 was only two years old.
In last week’s article, (‘‘Rex pilots narrowly avoided air disaster’’, 31/3), Byron Bailey said “the pilots took quick action to shut down an overheating engine”. Mr Bailey said the crew was shutting down the engine because gearbox problems were causing the temperature to rise.
Rex can confirm the engine was not overheating at any stage. Nor was its gearbox its “weak link”, as Mr Bailey said. This allegation is the view of an individual who is not a subject matter expert. There are no statistics to support such a view.
The allegation about the engine overcoming the drag inside the gearbox is also a figment of imagination. The General Electric engine fitted to the Saab 340 is a free power turbine and, as such, the engine and gearbox have no mechanical connection.
Further, I challenge Mr Bailey’s statement that, had the pilots not taken action to shut it down, the propeller would have “been spinning faster and it could have impacted the fuselage”. This allegation is emotive and unfounded. The propeller separated only when the first officer selected fuel off, which also feathers the propeller.
We wish to set the record straight on allegations on the industrial relations with the crew. Rex pilots are paid in accordance with an enterprise agreement and are rostered in accordance with Civil Aviation Order flight and duty time limitations. Overnight allowances have always been paid to Rex pilots in accordance with the EA.
Finally, Rex did not suffer three incidents during March. Rex experienced two unrelated events. The first was the propeller separation on Flight ZL768 on March 17. The second was engine failure on Flight ZL821 on March 23. In the third incident, the crew initiated an air return because they believed they could hear an air noise associated with the ground communications hatch. The flight did not have any other apparent issues. Engineers carried out a thorough inspection including ground runs and no fault was found. The aircraft returned to service.
In summary, every carrier in Australia and in the world suffers from similar safety events occasionally as this is an inevitable part of flying, no different from driving. What is important is the in-built redundancy of the aircraft, which allows safe operations despite component failures. These safety features have resulted in flying being much safer than driving in terms of injuries per kilometre travelled.
The Saab 340 is designed to be able to climb, cruise and land safely on only one of its two engines. This was demonstrated in the events cited in the article to the extent that many passengers said they did not feel any difference when the aircraft landed uneventfully after the propeller separation.
The other important contributor to flight safety is crew flying standards. The two events demonstrate the high quality of training of Rex crew such that normal landings are achieved even under rare and challenging circumstances. Rex has received universal praise from the aviation world for the calm, professional and effective actions of the crew after the separation of the propeller.
John Sharp is deputy chairman of Rex and a former federal transport minister.
Thanks for posting that; probably as well I'm not in PR because I'd have had a hard time being as polite about Bailey, Cleary and their woeful lack of technical knowledge.
As far as aviation 'experts' are concerned, they are not paid to be accurate.
They are paid to say something, anything, in order to make their media masters look good in the eyes of the public.
The media these days rarely report the facts in news reports. They exaggerate it, embellish it and twist the truth to make a good story.
They are paid to say something, anything, in order to make their media masters look good in the eyes of the public.
The media these days rarely report the facts in news reports. They exaggerate it, embellish it and twist the truth to make a good story.
Just saw GT interview on Sky via twitter. Pontificating as usual about what caused it with statements like "they believe this happened and they believe that happened" - who's 'they' GT... like he'd know... anything happens we don't have to worry because aviation 'expert' GT will be out front spewing out his uninformed rubbish.
http://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-032/
I'm not an engineer (perhaps just as well), but what I can see of the corrosion on the bore of the dowel hole wouldn't really run up any red flags if I'd seen it prior to the incident.
I'm not an engineer (perhaps just as well), but what I can see of the corrosion on the bore of the dowel hole wouldn't really run up any red flags if I'd seen it prior to the incident.
Last edited by spinex; 13th Apr 2017 at 02:22.
via spinex:
I'm not an engineer (perhaps just as well), but what I can see of the corrosion on the bore of the dowel hole wouldn't really run up any red flags if I'd seen it prior to the incident.
I'm not an engineer (perhaps just as well), but what I can see of the corrosion on the bore of the dowel hole wouldn't really run up any red flags if I'd seen it prior to the incident.
.
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Psychophysiological entity
It's astonishing how metal stays together . . . until suddenly it doesn't.
I doubt it was possible to get a clue as to the state of that shaft but there's just a chance the clues were there.
It's very different, but I was due to flight test a Heron and the aircraft was surrounded in tech-staff. I noticed a fine line on one of the engines and got a couple of blokes to rock the aircraft with the prop. The line glistened more on a push than a pull. The Crankcase was split from top to bottom on one side. Goodness knows how long it had been like that but it's doubtful we'd have survived the entire front of the engine breaking away.
I doubt it was possible to get a clue as to the state of that shaft but there's just a chance the clues were there.
It's very different, but I was due to flight test a Heron and the aircraft was surrounded in tech-staff. I noticed a fine line on one of the engines and got a couple of blokes to rock the aircraft with the prop. The line glistened more on a push than a pull. The Crankcase was split from top to bottom on one side. Goodness knows how long it had been like that but it's doubtful we'd have survived the entire front of the engine breaking away.