New Starter and More
When I left my last lesson it was after an unplanned use of the simulator instead of the airplane. My airplane’s starter wouldn’t start the engine. It’s been a couple weeks now, but the starter’s replaced. I also asked them to check and signed off an AD (airworthiness directive) on the alternate static air valve. But they found out the valve was stuck and needed replacement.
This a good thing to fix, but it’s just one more expense unfortunately. After all, the starter wasn’t cheap either! The three instruments for airspeed, altitude, and the vertical speed indicator all use the static pressure. The usual static pressure is from a small opening on the side of the plane perpendicular to the airflow. But, if that’s iced up, then those three gauges will stop working correctly. So, an alternate static air inlet is placed inside the plane and activated by a control tied to that formerly-stuck valve.
The air pressure inside an unpressurized airplane is a bit less than outside. It has to do with the way that cabins and tail cones are made and ventilated from the rear so that there’s a very slight vacuum in the cabin. So using the alternate (internal) static air isn’t as accurate as using the regular outside static air. But if the outside is frozen up, well, less accurate is better than no accuracy!
When trying to take the regular post-maintenance test flight, I flooded the engine on start and drained the battery with start attempts. Airplane engines aren’t like car engines, we have to prime them and adjust the mixture manually. When the weather is colder, more priming is required. I over estimated the priming needed and flooded the engine. While trying to crank it and resolve my overpriming, I ran down the battery. Airplanes have a smaller and less powerful battery than cars do to save weight. As it was pretty cold, the available battery power was less and that didn’t help either.
Fortunately there’s a way to, basically, jump start an airplane using an GPU (Ground Power Unit). I waited till a warmer day, then for yet another fee I got the local FBO’s help (Fixed Base Operator - the airport equivalent of the local gas & repair station) and started the plane.
This involves the FBO’s line guy moving near the front of the plane while the propellor is spinning. For safety’s sake, this isn’t something I usually let happen. But in this case it was the only way to handle it. So, we reviewed what we would each do, in what order, and what our signals with each other were to be. He was experienced with this and that helped a lot. I’ve jump-started a car before, and the theory is the same, but with a plane the procedure is a little different.
Our plane has an external power jack accessed through a small fairing in the side of the engine cowling. I removed that fairing and would replace it later after I landed. The line guy plugged in the GPU power cable and on my signal backed away and started the GPU. I then started the plane and waited with breaks on till he had unplugged me and was well clear. It’s a simple process, but I wanted no miscommunications and no accidents. The line guy was experienced and it all went off without a hitch.
Then I took three trips around the pattern to recharge the battery in beautiful calm air. I watched the ammeter to see when the charging was complete and put the plane away after the third landing. But I had some fun in the landings.
To provide more room for incoming traffic, I turned final quite short to the runway and put down all flaps. (A little bit of flaps - ten degrees - adds lift , but the more flaps you use the more drag slows the plane.) Then, reducing power to slow the airplane aggressively (but not too much) I descended quickly to land and hit that first turnoff. It was all very smooth and quick. I wouldn’t normally do this with most passengers since it could be viewed as alarming to see the steep descent angle I was using. But my airspeed was always in control and safely above stall speed and the airplane did exactly what I wanted it to do. I love those 40 degrees of flaps!