I am installing a 914 in a Kitfox SS7. I'm curious as to what standard practice is for measuring fuel pressure in flight. The way the engine is set up out of the box, it would seem that Rotax only intended fuel pressure to be measured as a diagnostic ground test. Do most installations include installation of afuel/airbox differential pressure sensor? In the same vein, do most people measure airbox temp and/or pressure? They provide a single port, but again, it does not appear that they thought this would be part of a standard install, or they would have simply this info available from the TCU.
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Re: 914 Differential fuel pressure measurement.
by Ken Ryan » 7 years ago
Although Rotax does not require it, I have been advised that it is highly desirable to monitor fuel pressure (as related to airbox pressure). UMA makes a specific instrument for this that connects to the fuel supply and the airbox, does the calculation, and sends the information you need (fuel pressure over airbox pressure) to your gauge.
According to Dean at Lockwood, he has never seen a 914 installation that measures airbox temperature. If you do decide to measure airbox temperature, and you have a Dynon Skyview, do NOT follow their instructions. They say to use a duplicate sensor of the same type that is installed for the TCU. This will not work. Their Skyview is not calibrated for that sensor and it will not read correctly.
I hope Rotax chimes in with their thoughts on these questions.
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Re: 914 Differential fuel pressure measurement.
by Brian » 7 years ago
I have seen the UMA setup. The sender is supported for SkyView, and could be installed pretty easily with a dual banjo bolt at the fuel pressure control and an npt fitting at the one free airbox port.
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Re: 914 Differential fuel pressure measurement.
by Ken Ryan » 7 years ago
Actually there are two free airbox ports. There is the one directly beside the airbox temp probe, and a smaller one underneath. I used the one next to the airbox temp probe for a second airbox temp probe (like I said it is not supported by Dynon, despite their specific instructions to use the same probe as installed by Rotax) and I used the smaller one for the dry side of the UMA fuel pressure sensor.
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Re: 914 Differential fuel pressure measurement.
by Brian » 7 years ago
For the fuel pressure measurement, in the parts manual, it looks like Rotax uses a Bing idle jet as an orifice in the banjo nipple. Has anyone done this setup? Do you need to tap the banjo fitting for the idle jet?
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Re: 914 Differential fuel pressure measurement.
by Rob Seaton » 7 years ago
you can just press it into the fitting.
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