How about Running a Tank Dry?
"Never run a fuel tank dry" is one of the newer ones, because it used to be a standard method of fuel management. We used to do it on virtually EVERY flight, before the jets came along! I still do it regularly, in non-turbine aircraft, and it works great. What happened to change this?
Now please, folks. I'm not talking about running a tank dry when it's the only tank in the airplane! Nor when it's the last tank with fuel in it! Some readers have blasted me on the checklist columns about single-pilot operations, saying "Well, how about the A-26, or the single-pilot Citation?" Folks, there are exceptions to every rule, and if you haven't got the smarts to figure that out, you not only shouldn't be reading this column, you probably shouldn't be flying (or even walking). As I tried to point out in "What Really Counts," you ought to read this, think about it, figure out what applies to you and what doesn't, and act accordingly. You don't like something? Argue about it! Find some data to prove I'm wrong! Please! I want to know more than anyone.
Who Started This Insanity?
In my opinion, the change in attitude was mostly due to turbines (jets and turboprops), in which even a tiny bit of air in the fuel supply may kill the engine. Turbines, as wonderful as they are, can be miserable or impossible to restart in the air, often requiring a descent into "thicker" air, specific airspeeds and windmilling RPM, and several systems have to function properly to get a re-light. The turbine is like a campfire on a rainy day. Keep it going, and it's fine, but let it go out, it can be really tough to get it going again. I suspect that as many pilots started flying turbines, the idea developed that running a tank dry was "a bad thing," and this attitude permeated down to the recips, as well.
This is simply not true of recips. When a recip runs out of fuel, nothing else has changed. The spark is still there on every power stroke, the piston is still pumping air, driven by the prop, which is nearly impossible to stop, inflight even when you want to. Two of the "three necessities" (fuel, air, spark) remain, totally unaffected by the lack of fuel.