Aviation Training Tip: Airplane Hydraulics

0:00After watching this quick tip video, be sure to check out our website at Wi-Fi-CFI.com. Our online aviation courses include Study Courses for the private pilot, instrument rating, commercial pilot, CFI, CFWI, and multi-engine app on Study Courses. All of these include videos, podcasts, quizzes, flashcards, audiobooks, practice FAA exams, check-ride workbooks, and more. We also have courses for just the check-ride lesson plans. These are to teach on those flight instructor check-rides. We've got the CFI, the CFWI, and the MEI add-on lesson plans. They all come in PowerPoint, PF, and dot formats, word formats. They're downloadable, customizable, printable. They've got animations, diagrams, images, included quizzes, and more. Additionally, we have teaching courses. If you're a flight instructor already and you want to teach your students, you can teach your private pilot instrument rating, commercial pilot, CFI initial, and CFWI add-on students with

1:03flight syllabi, lesson plans, homework assignments, binders and tracking, quizzes, logbook audits, endorsements, and more. And you can try every single one of our courses for free for as long as you would like at Wi-Fi-CFI.com. Moving on now with hydraulic systems. We've just got a couple systems left here to cover in this lesson. So let's go ahead and talk about how hydraulics work. They're often used on smaller planes to operate brakes like the wheel brakes, retractable landing gear, and some constant speed propellers. I wouldn't say they're too common as far as operating constant speed propellers, but you will see them for wheel brakes and retractable landing gear, definitely. Hydraulic system components include these different things. We've got a reservoir, a pump. Now the pump can be hand driven, electrically driven, or engine driven, depends on your system. A filter to keep the fluid clean cannot have contaminants and stuff inside of a hydraulic

2:06system. It just won't work. A selector valve to control the direction of flow or relief valve to relieve excess pressure if any excess pressure builds up and an actuator. You can see we've got a reservoir right over here. We've got our pump, got a system relief valve to relieve pressure. Again, selector valve will kind of talk how this works and then a double acting cylinder. Essentially, when you turn this pump on, fluid from this reservoir will pump one direction or the other. If it pumps down this way, I mean say it pumps down through here, right? And it comes through the pump, comes out this way and it can turn. Basically, this is what the selector does. The selector can send it this way or this way. If the selector sends the hydraulic fluid through the pump and you select it to go this way, it will come down over here and go to this side of the double acting cylinder. Now, this cylinder is basically just like the engine cylinders that we talked about earlier, except for it doesn't have fuel and air in it, right? It's got hydraulic fluid and this is a piston that's going to move up and down. So if we

3:10direct hydraulic fluid to the bottom portion of this piston, it is going to force the piston to come up. That's going to squeeze the hydraulic fluid out of the top and it's going to send it back this way. It'll open up this way, come back up over here to the reservoir. Now, if you flip your selector valve and you want to send, you basically close this part off right here, whatever, you send the fluid to the top of the cylinder, then it's going to push the piston down it's going to squeeze out all this hydraulic fluid over here, which will then get rerouted back to the reservoir. And that's exactly how landing gear can go up and down using hydraulic system components, right? What if you just put a tire right here? There you go. And now the tire is going to go up and down. You can bring it up and store it into the airplane or you can push it down and extend it back out. And that's how brakes work, too, with the clamping of the brakes, all the wheel brakes. And then we just went ahead and labeled those.

4:18And we just talked about this. So this would be if you're pumping to one side of the cylinder, right? Piston will move down and it would return flow back to the reservoir like so. Or you could do it just the opposite direction, bringing it that way, piston moves up, and the return flow like so.