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another Autoflight gearbox failure - this time after 34 hrs

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TarDevil

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Jun 29, 2010
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Coastal North Carolina/USA
The folks selling Jeff's Legend offer a Mopar 8.3L V10 with AutoFlight PSRU as a power option. I think I asked in this forum once if anyone has seen an aircraft so powered with no response.
To my ears, this engine sounds more like a Merlin than any LS V8 or the Falconer. I'm not an engine guy so I don't know if the V10 is a good aircraft engine candidate.
 

Jason Crossley

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Mar 2, 2020
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The Viper engine is an odd fire (90-54) degree engine. To me they sound like a bread truck when they go buy especially the earlier ones with side pipes. I'm surprised no one has done a split pin crank to address that. Most likely the addressable market is not big enough to sustain the engineering cost, but is certainly do-able. You would also need the appropriately ground camshaft as well. They are at their core an LA series (small block mopar) with an extra pair of cylinders. Decent aftermarket support as well. I know of a few that do standing mile, that are over 1500HP. Totally different use case than the workload seen in an aircraft, but they can make some steam.
 

MEDEVAC

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Apr 22, 2020
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Brisbane, Australia
Hi - I’ve read a couple of different stories. The main issues seem to stem from the engine. From what I have read on EPI-eng.com, another engine builder assessed the Falconer as inherently flawed. You can see a technical breakdown of the issues relating to harmonics. This would apply to the LSV12 as well due to the bank angle.
The gearbox suffers as a result of this.
I really like the idea of turbine performance and reliability as well as weight savings. I’m not sure the V12 option is great given all the issues with that power and transmission.
It’s a while before I have to worry to hard about that decision though.
 
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pantdino

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Feb 4, 2019
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Cerritos
UPDATE-- It turns out the machinist / mechanic who said the bearing was installed 15 thou off axis actually has never even opened the gearbox and looked inside. He's had it for 6 months now. I gather it's common in Aviation to have mechanics do this kind of thing, but I find it astounding. I have spent $5K on hangar fees and insurance while it sat on his floor and believed all the lies he told me about how it was "almost done."

It's back at the factory now and it was found the idler bearing had indeed failed, but because they had saved a few dollars by using a bearing that cost 1/3 of what their previous ones did. The owner there said the rollers had worn and tiny pieces of metal had come off their surfaces. He also said the shaft was damaged and is going to replace that and the bearing, this time with a quality piece.

I told him that according to the experts here the gear teeth need to be carefully examined and all the bearings replace.
 

wsimpso1

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Oct 18, 2003
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Saline Michigan
Sad story.

Once bearing debris gets up to a certain size, it does awful things to gear tooth faces, oil pumps, and other bearings. I hope it got stopped prior to that point.
Billski
 

pictsidhe

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Jul 15, 2014
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Hi - I’ve read a couple of different stories. The main issues seem to stem from the engine. From what I have read on EPI.com, another engine builder assessed the Falconer as inherently flawed. You can see a technical breakdown of the issues relating to harmonics. This would apply to the LSV12 as well due to the bank angle.
The gearbox suffers as a result of this.
I really like the idea of turbine performance and reliability as well as weight savings. I’m not sure the V12 option is great given all the issues with that power and transmission.
It’s a while before I have to worry to hard about that decision though.
Odd fire engines have a strong harmonic at half firing frequency. This needs accommodating in whatever is used to mitigate TV.
 

wsimpso1

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Oct 18, 2003
Messages
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Location
Saline Michigan
From what I have read on EPI-eng.com, another engine builder assessed the Falconer as inherently flawed. You can see a technical breakdown of the issues relating to harmonics. This would apply to the LSV12 as well due to the bank angle.
The gearbox suffers as a result of this.
Citation needed. I would like to read more about issues found in these 10 and 12 cylinder systems.
 
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