Waiex B down

[GraemeSmith]

Modify the intake to bring in cooler air to the carb, and your intake icing will get worse.

AeroVee 2.1, Aeroinjector, modified to get a direct shot of outside air on the filter. In 360 hours to me - never experienced anything resembling carb ice - including 20 hours X-Country last month - at least 18 of which were flown in 80% plus humidity.

I'm NOT saying it can't/won't happen. And when I first added the outside air I was extremely careful/cautious about the possibility. But it just has not happened.

--

Thus be interested to hear of proven instances and the equipment setup and environment where it has happened.

[Dave Wolfe]

Graeme,

This is the one that comes to mind. I believe this AC had cool air routed to the intake.
http://www.sonex604.com/crash.html

[GraemeSmith]

Graeme,

This is the one that comes to mind. I believe this AC had cool air routed to the intake.
http://www.sonex604.com/crash.html

Just to play "What If?" NOT to be a contrarian!

Jeff states:

"the cause of the engine failure was never determined"

A look at historical weather data for the airport he was landing at:

https://www.wunderground.com/history/da ... /2009-6-24

Puts the humidity in a range that COULD cause carb ice - though it is top right of the carb ice chart - and if it was the hotter part of the day - then the carb ice probability is very low.

Jeff doesn't definitively state it. Though the post engine inspection is VERY similar to planes found in fields where carb ice was suspected.

You really need some pretty serious venturi type pressure drop and vaporization to cause the kind of cooling that might form ice. And then it forms in the venturi of a butterfly type carb. A possibility is ice over the filter - but in the warms of the back of the engine compartment - still pretty low. I'd put carb ice at "not proven".

Another possibility (though Jeff mentions trying to adjust mixture) is overlean while descending without riching up. I know I have to pay attention to that - but I suspect Jeff has more experience than to fall for that!

Or even a mag failure. I just had one of those Briggs and Stratton lawnmower mags quit a couple of weeks ago. Ground Mag check - AOK. Two hours later as the fuel flow ticked up for no reason I could initially determine - an in air Mag Check and "Oh Boy" - one of the manual mags was clearly not playing. I was running (really badly) on two plugs when I dropped out the electric mags. Glad they kept running when I brought them back online and landed!

End of rambling.....

[Dave Wolfe]

Yep, these things are never certain!

Vaporizing fuel, no matter how its done, causes a temperature drop. While aerocarbs dont have the traditional venturi, they still cause a pressure drop at partial throttle which mimic the traditional way carb ice is explained in aviation texts.

The point Im making, is that these types of slide carbs are described as not being able to ice up. But thats misleading, as nobody in these conversations point out that the ENTIRE INTAKE SYSTEM DOWNSTREAM FROM THE CARB is prone to form ice.

[Area 51%]

If I were a betting man, my money would be on vapor lock, not intake icing.
It's so common in these planes they even went as far as giving it a "cutie pie" name......."the burps".
The cause is probably indistinguishable between the two scenarios of icing and vapor lock after the wreckage warms up or cools down.

[WaiexN143NM]

hi all,
kathryns report back online. more narritive posted in the report.
I reached out to a few friends to see if they know anymore about this accident.

a few people mention john denvers accident. i was working in the tower that day(oct12, 97) , faa mry tower/tracon.
he initially did 3 touch and goes off rwy28. L/R. (limit due to airport noise abatement) then flew west over the water off lovers point(point pinos) . was with radar departure control(one floor below the twr cab) . people saw the crash, called 911, who called coast guard and
faa twr. scuttle butt around airport (and later in ntsb report) john walked to a few open hangars got a vice grips to go on fuel valve. but not in correct position, surmise fuel starvation(plane low on fuel), twisting body to reach fuel valve, which was installed behind left shoulder. twisting body left caused rudder deflection which at low altitude caused the plane to dive /roll downward into the water.
i did see the remains of the plane. just small pieces .
very tragic indeed.
a group comes every yr on the day to do a fly over.


fly safe out there

WaiexN143NM
Michael.

[GraemeSmith]

Final Report on this issued last week.

No evidence of structural or engine failure.

Ethanol in blood but not conclusively to determine if that was the factor.

Probable Cause - "A loss of control in flight for undetermined reasons that resulted in an impact with terrain"

The ADDITIONAL INFORMATION on the end of the report is worth a read if you bought your plane on the secondary market and did not build it.

Report_CEN22FA375_105703_4_3_2024 11_54_37 AM.pdf

NTSB Final

(739.12 KiB) Downloaded 388 times

[Bryan Cotton]

Good to see you posting here again Graeme.

Sure sounds like a medical issue to me, but per the report they were unable to determine that conclusively. Looking back at our speculation, it seems some or all of it was off.

[builderflyer]

Sure sounds like a medical issue to me, but per the report they were unable to determine that conclusively.

I agree. Personally knowing this Waiex and it's builder, noting that the NTSB could not find anything wrong with the airframe or engine, and noting that the NTSB could not complete an autopsy on the pilot, I believe this accident was likely do to some form of pilot incompacitation. So sad for the pilot's family and friends and for the builder of this beautiful Waiex.

Art,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,Jabiru 3300 #261