Piper J3
Well Known Member
Shutting off electric fuel pump. This is being discussed in several threads again, so let’s just have the debate right here and now.
Rotax Installation Manual, and yesterday, the Vice President - Chief Engineer at Van’s Aircraft, are adamant about running electric fuel pump 100% for purpose of preventing vapor lock.
Can someone explain why they have elected to shut off electric fuel pump? Please explain in technical terms and not feels-good-to-do language. Please be specific and technical.
It is very hard for me to understand this behavior. It parallels what is happening now in this country with COVID vaccine reluctance. When something is proven effective, has scientific basis, explained well to the end user, with imminent danger if not followed – people are sticking their fingers in light sockets.
I experienced vapor lock several weeks ago and never want to have it happen again. I started a specific thread to discuss mitigation and now I read how happy people are to flaunt manufacturer’s advice on a safety related issue.
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Please read once again Van’s Aircraft – Rian Johnson, Vice President Chief Engineer:
To put an end to all of this discussion the main reason that there is a fuel pump in the RV-12 is to prevent vapor lock. Although some may not have an issue with the pump turned off, they may not be operating at a fuel type or density altitude that will cause an issue. Others may follow your lead and have an engine failure. There are multiple reports (that I know of) of pilots turning off the pump after reaching pattern altitude and experiencing partial power loss. The pump has been placed close to the tank to provide pressure all the way to the engine thus reducing the chance of vapor lock as the fuel passes through valves and gascolators (which may be points of cavitation/pressure drops where vapor can form) or heated fuel lines on its way to the engine.
A Rotax is not a Lycoming therefore do not add a switch to operate the aircraft in a similar manner. The pump needs to run all the time.
Next about checking the engine-driven pump. When you turn on the aircraft the fuel pressure will rise to a steady-state level. When the engine comes on the fuel pressure will rise to a higher level letting you know that the engine-driven pump is working.
What amazes me is why anyone would not want the electric pump running all the time? The pump is designed to be running all the time. These pumps will last for years and years and are only $40. Are people really risking their lives to save $40 over a period of 15 years (approx how long mine lasted on my RV-7) ... that is $2.67 per year. Not even a gallon of gas or a gallon of milk these days.
My main mission at Van's is to ensure that each and every one of you is safe. Let's do the right thing here and please just leave it running.
Rian Johnson
Van's Aircraft
Vice President Chief Engineer
Rotax Installation Manual, and yesterday, the Vice President - Chief Engineer at Van’s Aircraft, are adamant about running electric fuel pump 100% for purpose of preventing vapor lock.
Can someone explain why they have elected to shut off electric fuel pump? Please explain in technical terms and not feels-good-to-do language. Please be specific and technical.
It is very hard for me to understand this behavior. It parallels what is happening now in this country with COVID vaccine reluctance. When something is proven effective, has scientific basis, explained well to the end user, with imminent danger if not followed – people are sticking their fingers in light sockets.
I experienced vapor lock several weeks ago and never want to have it happen again. I started a specific thread to discuss mitigation and now I read how happy people are to flaunt manufacturer’s advice on a safety related issue.
-----------
Please read once again Van’s Aircraft – Rian Johnson, Vice President Chief Engineer:
To put an end to all of this discussion the main reason that there is a fuel pump in the RV-12 is to prevent vapor lock. Although some may not have an issue with the pump turned off, they may not be operating at a fuel type or density altitude that will cause an issue. Others may follow your lead and have an engine failure. There are multiple reports (that I know of) of pilots turning off the pump after reaching pattern altitude and experiencing partial power loss. The pump has been placed close to the tank to provide pressure all the way to the engine thus reducing the chance of vapor lock as the fuel passes through valves and gascolators (which may be points of cavitation/pressure drops where vapor can form) or heated fuel lines on its way to the engine.
A Rotax is not a Lycoming therefore do not add a switch to operate the aircraft in a similar manner. The pump needs to run all the time.
Next about checking the engine-driven pump. When you turn on the aircraft the fuel pressure will rise to a steady-state level. When the engine comes on the fuel pressure will rise to a higher level letting you know that the engine-driven pump is working.
What amazes me is why anyone would not want the electric pump running all the time? The pump is designed to be running all the time. These pumps will last for years and years and are only $40. Are people really risking their lives to save $40 over a period of 15 years (approx how long mine lasted on my RV-7) ... that is $2.67 per year. Not even a gallon of gas or a gallon of milk these days.
My main mission at Van's is to ensure that each and every one of you is safe. Let's do the right thing here and please just leave it running.
Rian Johnson
Van's Aircraft
Vice President Chief Engineer