Some of this depends on what you are going to use to display your fuel quantity. For example, a simple gauge and a capacitance type sending unit can be calibrated at the transducer to read full and empty correctly, but are non-linear in between. I replaced several Westach probes in my KR as the ground side of the capacitance probe kept losing contact with ground reference. They were just poorly made. I finally fixed the issue by pulling the probe and wrapping the ground wire and the ground side of the probe with .020 safety wire and zipping it down tight.
The float type gauges seem to be pretty durable, but I think everyone at some point in time has had a car with a failed gauge, so they do fail. Additionally, sometimes it takes a reiterative process of bending the float arm to get them to read full and empty correctly, and like the capacitance gauges, they are non-linear when they just measure the height of the fuel in the tanks. However,if you are using an electronic instrument display such as the integrated Garmin, Dynon, JPI, EI, or other displays, you can typically add fuel to each tank one gallon at a time and tell the display after each gallon is added until it's full. Then the display takes the non-linear transducer readings from your 1 gallon increments and creates a linear display of fuel quantity, either in gallons remaining or E-1/2-1/2-3/4-F. This can be done with the output from either capacitive or float type transducers. It's always important to have your tanks display empty correctly and you can leave the full mark subject to interpretation. My RV has float type transducers with electronic averaging, so they don't constantly bounce up and down and are stable in flight. However, the calibration was not completed correctly, so they only display just over 3/4 when they tanks are full. But they do indicate empty correctly, and that is what is important to me. If I were to integrate an electronic display in the future, I could leave those same transducers in the tanks and just calibrate the display as I fill the tanks in 1 or 2 gallon increments, and would end up with an accurate, linear display of remaining fuel with full and empty in the correct places. -Jeff Scott Arkansas Ozarks > Sent: Friday, February 11, 2022 at 12:43 PM > From: "Mark Langford" <m...@n56ml.com> > To: krnet@list.krnet.org > Subject: KR>Re: fuel senders and gauges? > > Brad at Great Western Airsports wrote: > > > VDO has never let me down in various aircraft, various setups, lots of > > hours. > > Yep, that's exactly what I used on N56ML. Having been a VW fanatic > since before I could drive, I'm a big fan of Bosch, VDO, Hella, etc, so > I installed a VDO 226-001 sending unit in my right tank. It failed with > just a few hundred hours of flying. > > I've had much worse problems with VDO oil pressure senders, both on 56ML > and 971JF. They get a bit whacko and start fluctuating wildly, almost > always reading lower than actual oil pressure, so I get nervous and > install a new one, which works for another hundred or two hours until it > happens again. I have a box with about seven dead pressure sensors in > it, and one day tested them with regulated air pressure and they were > all way off or dead entirely. And no, they're not mounted directly to > the engine, I've always fastened them to non-vibrating surfaces like oil > filter adapter, which is bolted to the firewall. > > No more input from anybody else? Nobody has a fuel level sensor with > 500 hours on it that you'd swear by? > > If anybody's interested, see http://www.n56ml.com/wingtank.html for more > on how I did the tanks in N56ML. I still think that was a pretty good > way to do it, other than not making the fuel sensor easily replaceable. > I could have done that by providing a mounting hole and an access > panel in the wing, but eventually I just used a fuel totalizer, which I > reset after filling up. I used a 6 minute timer to transfer fuel from > the left tank to the right tank, which was half the tank. On 891JF I > use a "calibrated" paint stick to check before each flight, but if I'm > going anywhere other than local, I just fill it up before I leave, and > fill it up again on the way back, and call it good enough. I plan for 4 > gph (but usually throttled back and doing better than that) with a 14 > gallon tank. > -- > Mark Langford > m...@n56ml.com > http://www.n56ml.com > Huntsville, AL > ________________________________ > -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html > -Change list delivery options at > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board > -Search recent KRnet Archives at > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > -Search John Bouyea's decades of archive at > https://www.mail-archive.com/krnet@list.krnet.org/ > ________________________________ -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html -Change list delivery options at https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board -Search recent KRnet Archives at https://list.krnet.org/empathy/list/krnet.list.krnet.org/ -Search John Bouyea's decades of archive at https://www.mail-archive.com/krnet@list.krnet.org/
