Propellor falls off Rex Saab 340 in NSW Australia
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The report will tell. Should not be too difficult to determine forensically. Fatigue initiated by corrosion pit, tooling mark, could be anything.
In my perusal of the data, that is extremely rare in powerplant related failures.
Such things as gun-drill tool marks, unchamfered oil holes, and quench cracks come to mind.
Barret1 probably has some more in mind
Such things as gun-drill tool marks, unchamfered oil holes, and quench cracks come to mind.
Barret1 probably has some more in mind
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Parallel thread
http://www.pprune.org/australia-new-...highlight=saab
And yes, I've seen a raw material defect or two - foreign material inclusions, a forging lap so blatant it failed on the first engine runup, sharp-corner stress riser, crack originating from the p/n marking area. . .
Highly engineered materials that must be properly manufactured, or they are guaranteed to fail!
And yes, I've seen a raw material defect or two - foreign material inclusions, a forging lap so blatant it failed on the first engine runup, sharp-corner stress riser, crack originating from the p/n marking area. . .
Highly engineered materials that must be properly manufactured, or they are guaranteed to fail!
Last edited by barit1; 21st Mar 2017 at 17:38.
Prop/fan shafts can fail for a variety of reasons. I recall a fan shaft failure on a nearly new turbofan engine a few years back that was traced to the wrong anti-seize assembly lube being used.
I don't recall the details (and metallurgy isn't exactly my area of expertise), but IIRC the assembly lube promoted stress corrosion on the threads that lead to the shaft failure.
I don't recall the details (and metallurgy isn't exactly my area of expertise), but IIRC the assembly lube promoted stress corrosion on the threads that lead to the shaft failure.
A previous 340 event where the prop was lost, in an identical manner to this, was found to be caused by a slag inclusion in the shaft. DC-10 had a similar event where a fan disc contained inclusions and let go with eye watering results.
Prelim Report
Well here's the prelim report, seems the pprune aib got it more or less right; Investigation: AO-2017-032 - In-flight propeller malfunction involving SAAB 340 VH-NRX, 19 km SW of Sydney Airport, NSW, on 17 March 2017
Well here's the prelim report, seems the pprune aib got it more or less right; Investigation: AO-2017-032 - In-flight propeller malfunction involving SAAB 340 VH-NRX, 19 km SW of Sydney Airport, NSW, on 17 March 2017
Of note
This is the first known critical failure of this type
Straight forward metallurgical techniques/examinations. including possible abusive machining. Typically this kind of stuff is batch related and a get well plan already in progress.
No doubt the ATSB or equiv is involved in the precise details of the cause and they will probably close out their invest when satisfied that the regulator has addressed the findings.
No doubt the ATSB or equiv is involved in the precise details of the cause and they will probably close out their invest when satisfied that the regulator has addressed the findings.
