Check the caps-monitor the guages

[pelmet]

Actually, even if you prefer not to climb up to physically check the caps, you can see them from behind the aircraft if at a reasonable distance.

"C-GZPV, a Cessna A152 aircraft operated by Canadian Flight Centre, was conducting a local
training flight from Vancouver/Boundary Bay (CZBB), BC with 2 persons on board. During the
return flight to CZBB, the aircraft experienced a loss of power. The instructor-pilot declared a
MAYDAY, and conducted a forced landing on Highway 17. There were no damage to the aircraft,
and no injuries to the 2 occupants.
Further inspection revealed that the right hand fuel cap was missing, and both fuel quantity
indicators were at zero"

Picture with news article here.....

https://www.citynews1130.com/2019/06/14 ... ighway-17/

[goingnowherefast]

I'm surprised anti-siphon/flapper valves haven't made it to small aircraft. It's just a piece of mental on a spring hinge mounted on the inside of the tank opening. It pushes out of the way when a fuel nozzle is inserted into the tank. Spring holds it closed so gas doesn't get siphoned out should the gas cap go missing.

[digits_]

I'm surprised anti-siphon/flapper valves haven't made it to small aircraft. It's just a piece of mental on a spring hinge mounted on the inside of the tank opening. It pushes out of the way when a fuel nozzle is inserted into the tank. Spring holds it closed so gas doesn't get siphoned out should the gas cap go missing.

Some do, but even then there is only a point in using them if the fuel gauges are reliable. Even those siphon protection systems will usually still leak fuel.

The best protection would be to put the fuel caps in an area where there is almost no negative pressure. If I'm not mistaken, that should be the case in a 172. Then again, if you do circuits and go through a whole speed range, I'm sure you'll create negative pressure at some point.

Pipers tend to really suck out a lot of fuel right away if the fuel caps are missing, if I can believe the old war stories.

[goingnowherefast]

Been a while since I flew Cessnas, but I still seem to remember the old adage: "Cessna fuel gauges are only good for indicating that they are Cessna fuel gauges".