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Red cube single point failure potential ?

L

Larry DeCamp

Well Known Member
Recently in the thread referencing Manifold Pressure , one post raised the potential that a faulty RedCube could terminate fuel flow. Since this possibility could concern or affect many VAF participants, I called Electronic International for the facts.

They said, “ the red cube has been verified to support fuel flow in the event of RedCube malfunction. The total loss of fuel would be caused by occlusion of the fuel supply line “

I hope this comforts Red Cube users and avoids unfounded conjecture on this great community forum.
 
Failure

A friend had a total engine failure on takeoff in a Lycoming powered EAB(not an RV) No question this was a red cube failure. The manufacturer is aware and "investigating". Airplane landed safely on remaining runway. I know a lot more but don't want to provide further info at this time except to say that I do not and will not have a red cube on my airplane.
 
jrs14855 said:
A friend had a total engine failure on takeoff in a Lycoming powered EAB(not an RV) No question this was a red cube failure. The manufacturer is aware and "investigating". Airplane landed safely on remaining runway. I know a lot more but don't want to provide further info at this time except to say that I do not and will not have a red cube on my airplane.
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Jim, I have a lot of respect for your knowledge, but find it hard to buy fault for the red cube. How about some tech support for your statement?

As I see it, there are only two possible failure modes which could restrict flow, those being a blocked passage or a locked rotor.

A blocked passage is possible, given a large enough chunk of trash in the incoming fuel. Pretty sure we saw one of those cases in an NTSB report, where a guy used silicone sealant on threaded fittings, and chunk blocked the inlet. I even recall tracking down such a chunk in the Facet pump inlet on the RV-1. That said, I find it hard to blame EI or Facet for trash.

As for a locked rotor, see the photos. Plenty of space around the rotor. It can't block flow, even it to were to lock, which is unlikely.
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.02 cents worth. I agree with Dan in this case. I have never heard of the shutter wheel failing in a FT60, to the point that its 'locked up'. Even so, I think its design would allow fuel flow around the 4 little paddles to keep the engine running. Dan would probably know better, since he did the cutaway of one several years ago.
It would take some pretty large debris to block the fuel port---port is about .125 ID--- and that would mean with the filters in use today, 10 micron to 100 micron, thats sounds like an unreasonable possiblity. IF the cube is mounted downstream of all the filters like most of them, something else had to have occured. Like the previously mentioned case above.

Tom

PS-- for all of you that hav huge concerns over your fuel line sizes---yes several have upsized from -6 to -8, just remember the passage in the FT60 is .125 ID, where a -6 teflon hose is .320 and the stem ID is +- .253. Still has enough flow to feed IO540s with no problem.
 
DanH said:
I did hear of a possible third failure mode, so let's be patient.
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Not sure what this third possible failure mode is, but I guess if one over-tightens the AN fittings the cube itself could crack and leak fuel.
 
jrs14855 said:
A friend had a total engine failure on takeoff in a Lycoming powered EAB(not an RV) No question this was a red cube failure. The manufacturer is aware and "investigating". Airplane landed safely on remaining runway. I know a lot more but don't want to provide further info at this time except to say that I do not and will not have a red cube on my airplane.
Click to expand...

Well? What was the outcome...7 months later, no update?
 
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