Rex incident YSSY

[LostProperty]

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.

[MickG0105]

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.
Here's the article;

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.

[spinex]

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.

[Capt Fathom]

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.

[AerialPerspective]

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.

[spinex]

http://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-032/ (http://www.atsb.gov.au/newsroom/news-items/2017/saab-propeller-malfunction/)

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.
(http://www.atsb.gov.au/newsroom/news-items/2017/saab-propeller-malfunction/)

[megan]

In a stressed component corrosion is often the source of fatigue cracking.

[Flying Binghi]

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.

Reminds me of some corrosion i've seen on sprockets on farm machinery. A loose rusty bolt to thin for the hole it is in will give that 'smeared mud' effect seen in the lower left quarter of the ATSB photo. The next stage is the bolt rusts up enough to lock into place embedding the rust flakes into the sprocket hole.




.

[barit1]

In a stressed component corrosion is often the source of fatigue cracking.

Yes, anything that degrades the surface finish; a scratch, improper part marking, . . .

[Loose rivets]

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.

[Derfred]

All this metallurgy discussion is fine, but John Sharp's article disputing Bailey's report is interesting to me. He disputes the "engine overheating" theory, fine. He then admits the the prop only sheared off after the crew cut off the fuel to the engine. Now maybe they didn't cut off the fuel due to engine overheating, but they certainly did cut off the fuel. Why? According to the PAN call: "uncommanded engine operations and then our propeller has just sheared off."

So something, observable to the pilots, happened prior to the prop shear, which was enough to prompt a shutdown. Were these "uncommanded engine operations" the cause of the prop shear? Or perhaps merely a symptom of the prop partially shearing prior to completely shearing? Is the gearbox still ok?

[barit1]

. . .
So something, observable to the pilots, happened prior to the prop shear, which was enough to prompt a shutdown. Were these "uncommanded engine operations" the cause of the prop shear? Or perhaps merely a symptom of the prop partially shearing prior to completely shearing? Is the gearbox still ok?


It was noticeable, and worsening, vibration which motivated the crew to shutdown #2. It was during this sequence the separation occurred.

Per Investigation: AO-2017-032 - In-flight propeller malfunction involving SAAB 340 VH-NRX, 19 km SW of Sydney Airport, NSW, on 17 March 2017 (http://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-032/)

And while I'm sure the PGB will get a thorough teardown inspection, I don't see anything at this point that would be distressed, other than possible bearing brinelling.

[Ejector]

What would happen if it was feathered while still (un-commanded possibly) producing a decent amount of power ?

[barit1]

It would cause an over-torque (or near so) condition, probably requiring a PGB teardown inspection.

[Andy_RR]

It may be the light, but if you look at this photo, there seems to be a surprising number of nuts missing from the (presumably) propeller hub studs. There is in all the pixel fuzz apparently one remaining at around 10 o'clock as displayed. Odd!

http://www.atsb.gov.au/media/5772523/saab340_prop.jpg

[Capt Fathom]

Andy_RR
This was a topic of discussion a couple of pages back when the prop was found!

[Andy_RR]

Ah, yes. Sorry Capt. I got bored hammering through this and the other thread before posting - big mistake!

My thoughts follow Leadie's conspiracy theories though. Why would you publish such a photo in a prelim report when someone official would presumably have officially documented the entire recovery process - you know, as found, turned over, dirt and grass brushed away etc. The guys there seem well equipped with cameras but no sign of any spanners in hand.

It seems strange that you'd publish such a trophy hunt photo without at least explanatory notes regarding the missing nuts, even if to remove the potential for conspiracy theories to hatch...

[jonkster]

It seems strange that you'd publish such a trophy hunt photo without at least explanatory notes regarding the missing nuts

They are clearly unaware of Jonkster's Second Thereom.

Jonkster's Second Thereom: when calculating the likelihood of people making up a conspiracy theory to fit the evidence, you will always underestimate it.
Even when you take into account Jonkster's Second Thereom.

[Lead Balloon]

How many similar pictures have you seen published by ATSB, jonkster?

Post one link to one picture with ATSB staff holding a piece of aircraft, which piece may be related to an incident, published by the ATSB.

Just one link.

If those pictures were taken and made available to someone by the ATSB, you don't have to bother with 'conspiracy theories'. The organisation would, in that case, evidently be a complete basket case.

[spinex]

Sounds as though it's not only Rex's Saab missing a few vital bits.:E

[Ralo]

Final report is out

(my post count too low to post link)

[Buswinker]

Final report is out

(my post count too low to post link)

https://www.atsb.gov.au/newsroom/news-items/2018/in-flight-propeller-loss/