Zenith Aircraft Builders and Flyers
Online Community of Zenith Builders and Flyers
Aux.or Boost fuel pumps
I was asked to tear down a plane that had crashed, and find the problem , the FAA and Rotax had inspected the plane and decided it was a pilot problem, the fuel bowls were empty and they were able to bypass all systems and start the motor , I found the FACET fuel pump that was inline to have failed and totally shut off the fuel, one person died because of the crash, DO NOT PUT A PUMP INLINE < PUT IT IN A BYPASS LOOP or leave it out you do not need a boost pump on most aircraft engines , also fly the plane no matter what happens ...BOB
Replies to This Discussion
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Permalink Reply by Gary Welch on
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Facet makes a number of different pump designs. Can you share which one it was?
Also can you explain how the pump failed to block the fuel flow?
I have facet pumps on my plane si any info that you can share would be appreciated.
I do understand that there may be legal reasons for not stating more than you already have...
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Permalink Reply by Bob Jones on
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It really doesnt matter what ELECTRIC pump you are using , if it is in- line{the only path to the mechanical pump] it can come apart internally and has the potential to plug up the only path to the motor , the point being to put any secondary pump in a by-pass line , 99% of elect. pumps are not aircraft rated or approved and you can not pull over to the curb ..BOB
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Permalink Reply by Shawn Magin on
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what exactly failed on the inline pump?
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Permalink Reply by Jim and Amelia Isaacs on
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Bob,
First, thanks for sharing. But there are many Experimental aircraft flying with Facet boost pumps, I plan to install one in mine. Facet makes pumps that are designed to leave the flow path open when power is removed, so can you confirm what model number pump was involved? And if this was the type pump that is designed to keep the flow path open with power removed that was involved in the mishap, then something inside the pump failed that blocked the fuel flow path. To echo Shawn’s question, Has the pump been returned to the manufacturer for tear down analysis?
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Jim, you are 100% correct , something came apart inside the pump , I actually thought I had made that clear , all pumps allow gravity flow in one direction , this pump is totally blocked both ways, and the filter which should always be installed before pumps was cut open and found spotless,I know and have worked on lots of set ups that have boost or emergency pumps but they Mostly have been installed in by-pass loops there - by giving double safety and back up , from the exit of the switching valve a "Y"should be installed with the ELECT. in one line and the MECH.in the other then rejoin before the carbs with a second "Y" both ELECT. and MECH. pumps have reverse flow checks , so can independently supply the carbs ... p.s. does any one know if Facet or and other aftermarket elect. fuel pump supplier sell a AIRCRAFT rated pump or are they all automotive ?? I will try to call Facet and ask if they approve their pumps to be installed in airplanes ,
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Permalink Reply by Joe Spencer on
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I don't doubt what Bob tells us or have a need for further proof. We all know Murphy's Law...if it can fail it will. Like others, I've seen it time and time again.
IMO, what's important is personal risk tolerance. We all know that Facets have been running in planes for decades with very few problems other than they quit pumping, I've only heard of one blockage now. If you wanta be as safe as you possibly can then assume it's gonna fail and block and install the bypass Bob recs, if you wanta play the odds then put it inline.
Your choice. Simple.
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Joe, thank you for your support , if someone wants to die for the cost of [2] "Y" fittings and [4]hose clamps then its their choice , I think its called evolution or survival of the fittest..BOB
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Permalink Reply by Mack P. Kreizenbeck on
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what's the chances of the electric pump reversing the flow in a bypass loop? instructions on my Jabiru did not mention a bypass.
Mack
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If you have two electric pumps in parrallel you need to add check valves at each pump outlet. This also represents two more potential points of failure.
There is a not-so-old post on either this forum or the 601 forum where this issue was discussed in detail.
Another member had a similar pump failure and redesigned his fuel system as a result.
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Gary, I have a single pump push pull fuel from two tanks on my 601 with no check valves. I researched both forums for this subject - only finding this particular discussion.
For clarification, I think I understand what is being what is being said here - that I should "T" my line on the upstream side of the pump running one line through the pump and the other parallel the pump into another "T" before entering the upstream side of the mechanical pump.
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Mack, depending on what pumps you have , the elect. pump is best in a bypass loop, there-by making it a true back up to the mechanical , normal bypass would be a 'Y" fitting after the tank selector valve with one line to mech. pump and second line to elect. pump then a second "Y"rejoining the pumps with one line to the carbs
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I dont really understand the question, if the internal output check valve in a elect. pump stuck open and ran no output pressure would realized , but if the elect. pump failed , and you are only using it as a back up then now you are saying both of your pumps failed , and its probably time to look for a suitable crash site
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