Unusable fuel is defined as that fuel that won't reach the engine in the most critical attitude. So if you have to abort a landing and go to Vx to clear the powerlines, will there be enough fuel in the tank to avoid unporting with the nose high like that? Or is your power-off, full-flap glide attitude steep enough to unport? The Cessna 150 is bad for that.When I wanted to calibrate some ways of determining how much fuel I had, I ran one take until the engine sputtered. Close enough to no usable fuel for me.
You can't switch tanks in a 150. The thing only has an on-off fuel selector (like the Navion
).
That doesn't tell you that you weren't sucking unusuable fuel. When I calibrated my fuel gauges worked my way from full tanks down to what the manufacturer claimed the usable fuel was. (39.5 gallons).When I wanted to calibrate some ways of determining how much fuel I had, I ran one take until the engine sputtered. Close enough to no usable fuel for me.
It keeps blinking at you even if you acknowledge it? That would be annoying.
It stays lit up. There's no way to tell it you don't care.
My aux tanks on my MVP 50 just go to 0.0 with no warning The mains flash yellow at 7.5. Sounds like you just had it set up wrong
I hope you are not unpleasantly surprised some day. But, based on experience, slipping into a low tank can result into an "oh ****" moment if you decide do go around.
I also used a vibrating handband timer during my training. Setting up the timer for 30 min intervals was part of my preflight custom checklist and starting the timer was in the takeoff checklist.
Yeah, I know that it's all configurable. When I put the new magnetic fuel sensors in, they walked me through some of the config changes. While I can see the alarm being useful on the main, the aux tanks really are designed to be run dry or left empty. I may have to call Dave up and get them to let me change that.
Unless you forgot to fill or sump the other tank. Then, definitely do forget to switch tanks.
Fun FactThe thing only has an on-off fuel selector(like the Navion
My aux tanks don't have any unusable fuel (or perhaps it is all unusable). They're placarded for level flight only and you can draw them empty.
Underseat tank. Had to be empty. You can actually take off on the under seat aux. The tip tanks (whose valve is usually 90 degrees left and right of the main) can only be used in level flight and there has been at least one notable crash where people have lost power trying to takeoff on those. The baggage aux tank (which I have in addition to the tips) gravity feeds into right tank when you pull a different handle. Of course, no two Navions quite have he same fuel system there days with the plethora of STC'd aux tanks and the fact that the money grubbing people who bought the type certificate crammed an AD on the fuel selector through in hopes that everybody would have to buy one from them. Fortunately, the ADO who issued the AD, was very gracious in approving AMOCs. The type society provided a better valve (with a positive lock to keep you from inadvertently selecting OFF) and A/N fittings that fit flush into the floor like the original one did (so you don't break the handle stepping on it). The "factory" one is the same manufacturer (Andair) valve without the lock off, mounted so it sticks up out of the floor, and uses banjo fittings that don't also fit very well. Mine came from JLOsborne. It's essentially identical to the one that came with the tip tanks originally except it has a part number stamped on it now. All Navion fuel valves were off-the-shelf Stuart-Warner industrial valves rather than specifically being an aircraft part.
