It's even more embarrassing in an airplane. Had a customer call me on a Sat morning about 10. Said he had made a dead stick landing in a bean field 80 miles east of me. I asked if he had any gas in the tanks and he said I am sure I have about 45 minutes left in the tanks.
This is a 1941 Waco biplane with two 25 gallon tanks in the upper wing center section. Only gauges are a float in a clear glass tube. She burns 13 gals per hour so 45 minutes remaining fuel should be about 10 gallons.
I drive over and the first thing I do is open the fuel strainer at the bottom of the firewall. No gas. I pull the hose off the carb/no gas. I open the carb bowl's drain plug no gas. I take a plastic container and remove the drain plugs from both sight gauges and I got the 3 ounces out of each that lays in the gage all the time.
I turn to the owner and I said "I think you are out of gas"!
Fortunately he only tore off one of his main wheel pants, I pulled the other off, threw them in my truck, added 15 gallons a side gas and the farmer chopped down two rows of beans and my customer flew her home.
That Monday I went to my customer's hangar and drained both tanks empty. Then using the metered pump I filled both. Both of these 25 gallon aluminum tanks only held 20 gallons! Apparently over the years they had been reskinned and the repairman failed to keep the size where it was.
Is there a moral to this story. It's a little routine I always did whenever I buy a used car. I put a 5 gal can of gas in the back and drive it till she quits. I take a marker and mark the position of the needle in the gage. I will never run out of gas with this car since I know exactly where the gage reads a true empty. Now I know you are all laughing cause this is an airplane! Well if it had a single tank you should be laughing. But it has two tanks so you run both down to about 1/2 tank based on flying time. Then you run on a single tank til the engine sputters then you switch to the other tank and land. Now determine the remaining fuel level in the tank you had run empty. Drain the remaining gas from that tank in a measured container. This is your trapped or unuseable fuel for that tank. Now fill that tank record how much fuel it actually holds. Record that number and right next to it right the unuseable amount. Now go fly again and do this all over with the other tank.
Long winded I know but it was a lesson learned and appreciated by that customer.
Now back to Ryan. We all know that the most unreliable system on the M38 is it's old electrical gauges. Knowing this the only alternative to insure adequate fuel is to verify fuel level in the tank. Here's where you reach in the glove box and grab that flashlight and that calibrated dipstick!
