Captain Avgas
Well Known Member
Some years ago Vans introduced an air induction bypass vent in the bottom of the filtered air box (FAB) on all models. The idea was to provide an option to get unfiltered air from the lower cowl to the engine in the event of an induction blockage at, or prior to, the filter in either carburetted or FI engines. The introduction of the bypass vent reportedly followed a couple of serious RV accidents involving induction blockages.
Vans first attempt was a magnetically held hinged flap vent. It was not one of his better ideas and there were many failures reported. Then a couple of years ago he scrapped the magnetic vent and replaced it with a pivotting vent which is still being supplied today on all FWF kits.
I note however that on August 30, 2006, John Ross reported that his new pivotting bypass vent had totally failed after only 50 hours of operation on his RV8. I have attached a photo supplied by John which clearly shows the classic aluminium stress crack which caused the vent to depart the FAB. Bear in mind that this material is .063" thick.
This is a critical component. No-one would want any parts from this component failing and being sucked up into the engine.
It is now 18 months since John's incident and it would be interesting to know if any other builders have experienced failures of the pivotting bypass vent (or operational problems of any kind).
For those with fuel injected engines in particular (no carbie heat bypass) it would seem to make sense to have an alternate air source, particularly if flying IFR. But if the bypass mechanism is dodgy the cure may be worse than the ailment.
Any feedback out there ???
Left click on photo for enlargement.
Vans first attempt was a magnetically held hinged flap vent. It was not one of his better ideas and there were many failures reported. Then a couple of years ago he scrapped the magnetic vent and replaced it with a pivotting vent which is still being supplied today on all FWF kits.
I note however that on August 30, 2006, John Ross reported that his new pivotting bypass vent had totally failed after only 50 hours of operation on his RV8. I have attached a photo supplied by John which clearly shows the classic aluminium stress crack which caused the vent to depart the FAB. Bear in mind that this material is .063" thick.
This is a critical component. No-one would want any parts from this component failing and being sucked up into the engine.
It is now 18 months since John's incident and it would be interesting to know if any other builders have experienced failures of the pivotting bypass vent (or operational problems of any kind).
For those with fuel injected engines in particular (no carbie heat bypass) it would seem to make sense to have an alternate air source, particularly if flying IFR. But if the bypass mechanism is dodgy the cure may be worse than the ailment.
Any feedback out there ???
Left click on photo for enlargement.
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