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Jabiru engine failure


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First, I have great empathy with the pilots and passengers who experience door, canopy and windscreen failures - I have experienced a bubble canopy coming open in flight myself; it was not a pleasant experience. In comparison, losing a piece of windshield must have been extremely frightening. Thankfully, such experiences are extremely rare.A few facts about the above references to the Foxbat may be helpful.

 

1. There have been no reported cases of 'vapour lock' in the 1000+ worldwide fleet of Foxbats - except for one aircraft in SE Queensland. This is because the wing tanks provide a continual fuel pressure of at least 0.5 bar to the pump, precluding the possibility of vapour lock. Almost certainly the cause for the reported engine misfiring in SE Queensland was carburettor ice: long descent from altitude, high humidity, no engine warming, misfire disappears as the aircraft descends into and remains in warmer air.

 

2. Apart from one documented birdstrike in SE Queensland, there have been two reported windscreen failures in Foxbats worldwide - one in Kazakhstan and one in SE Queensland. That's a rate of 0.002%. The Foxbat windshield is 2mm polycarbonate sheet, UV-proofed and scratch resistant, manufactured by Veralite in Belgium; it is the same as other polycarbonate sheet manufactured under trade names like Lexan, The product is used because it has excellent weather resistance and remains flexible even after prolonged UV exposure. Both incident aircraft were known to have had substantial cracks in the windscreens before the incidents, particularly along the front edge by the firewall. Cracks can be induced for a variety of reasons - they are most common in flying school aircraft, which have very high landing numbers per hours flown and more than their fair share of heavy landings.

 

The Foxbat maintenance manual clearly covers what to do if cracks appear in the windscreen, including replacement in some circumstances. Personally, if I found a windscreen crack in any aircraft longer than an inch/25mm or multiple small cracks, I'd replace the screen rather than stop drill the cracks.

Something wrong with the numbers here:

 

For the wing tanks to provide a continual fuel pressure of 0.5 bar to the pump under gravity, they would have to be something like 6metres higher than the pump.

 

And for the polycarbonate failure rate of 2 to be 0.002%, the manufacturer would have to have made 100,000 Foxbats.

 

I have no axe to grind here, but I greatly dislike this sort of inaccuracy, which just muddies the picture.

 

 

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He ran out of fuel and the engine seized Keith?That's a new one.

Could be a rolling seize, could be a freeze seize, consider the original evidence -- spit a piston then seized.

Fuel will cause seizures. Restricted fuel will cause seizures.

 

No evidence for a sensible comment.

 

KP

 

 

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There have been no reported cases of 'vapour lock' in the 1000+ worldwide fleet of Foxbats - except for one aircraft in SE Queensland

Well I wouldn't expect their to be a problem in the UK , it appears the LAA are on to it.

 

http://www.foxbataircraft.com/resources/A22,A22L,A22LS%20type%20acceptance.pdf

 

Section 2.6 LAA REQUIRED MODIFICATIONS item 5.

 

cheers

 

Jim G

 

 

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ALL A/C types have to pass a fuel flow rate adequate for engine type fitted test. A gravity feed of about 1.5 metres isn't much pressure head and hydrocarbon fuels densities are roughly 3/4 that of water where 1 bar = 33 feet. It might flow ok with large pipe sizes but there's no protection against vapourisation with no fuel pressure increase available from a pump with cool(er) fuel at the intake of it. Nev

 

 

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