If you remove/disconnect the p leads the mags are hot!! P leads connected keeps magneto grounded. And tell big man to stay away from the path of the prop especially when you got p leads disconnected. P-leads connected means its grounded and wont fire.

I am a current A&P and just wanted to give 1 small tip that could minimize a potential hazzard. When you are introducing the air pressure into the cylinder, instead of opening the valve all at once you should instead,, "creep" up the pressure until it slowly climbs to 80. This gives the person holding the propeller both time get a feel for it and a little leeway in case you are on the wrong position for the piston.

I think you meant make sure the p-leads are correctly attached and grounded with no frayed wiring.

I got to feel how hard that prop hits, my head was in the way of it while i was rotating it. It resulting in me getting 4 stings and a permanent scar

Well done!

Good video, you need to add how to find top dead center on compression of each cylinder

this is so informative thank you

great job

good vid keep them coming

Good deal for Megan! I bet that she makes a great A&P!

its a Lycoming Engine. But as of March 2013 TCM came out with SB03-3. As an A&PIA I can tell this document has changed the old way of doing Differential compression checks. I would read up on it and start doing the tests the way the manufacturer intends. It is not mandatory to do the test their way for Lycoming engines but I would highly reccomend it. You would need to get a Differential compression tester with a Master Orifice. But those are cheap enough.

informative video. thank u.

Love these videos, would be great if you could do one on oil changes, including filter/screen inspection!

What a great video, thanks for sharing this maintenance task. It’ll help a lot of pilots and airplane mechanics to better understand the steps through the compression check procedure. It’s also a great opportunity to no native english speakers to learn more technical aeronautical vocabulary related to this task. Thanks and keep sharing this videos !

This is a cylinder leakage test! A static compression test would be just a gauge in the spark plug bore while cranking the engine. A dynamic test would be with gauge connected and the engine running at a specific rpm. The pressure found during a dynamic tests would be an excellent pressure to test the cylinder leakage at.

Did I hear you say that removing the P- leads will keep the engine from firing? Please become informed yourself, then either remove this video, or remove the dangerous and misleading information, and remake the video with correct info. There are people who actually use the internet for accurate information. This is information that’s bad enough to kill someone. By the way you need to ground the P-leads to ensure no spark. Removing them is the same as leaving the key on.

Some props may continue spinning, faster and faster until the air connectiom is released.

this is a leak down test, a compression test would involve cranking engine and seeing how much pressure builds. This test measures how much air gets past the rings and valves.

Am I seeing things or did he just apply pressure to number 3 cylinder without bringing it up on tdc

This is what we call in holland a cilinderleaktest...not a compressiontest. A compressiontester had one gage and show u the max BAR/PSI

Just watched another video on "checking for induction leaks." Seems like it would be logical to perform this test in conjunction with this test. Are all the plugs removed and inspected at 100 hours? As others have said, seems like a good idea to remove plugs before doing this test. Of course one plug would be re-installed on as each cylinder is tested. link to induction leak test: kzfaq.info/get/bejne/ecx3Z7R425PWZmg.html

How i can lear how to be a mechanic ? (172/152)

This is the most in depth and well explained video on compression checks I've seen!

I call this a leak down test.

Continental vs Lycoming ?

Perfect example of what's wrong with aviation maintenance These people don't know what they're doing. What is the customer paying for? a couple of hacks? Disconnecting the P-Leads so the engine doesn't fire are you kidding me? The way the female is leaning on that engine there's no way it's at operating temperature as required. There is no way you're using the right size orifice in that ancient - out of calibration certification - tester. Look it up in AC43.13-1B Ch 8-14 b. (2). Customers fly their families in these airplanes. They expect those who work on their airplanes know what they're doing. You're a customer who has the choice of maintaining your airplane at two places Place 1 has hacks who weren't formally trained, didn't study the material, were taught by losers, are supervised by the same Place 2 has formally trained mechanics who know tactics, techniques, and procedures, were supervised by other smart people and know the material because they've studied it. Who cares, as long as they have an A&P license right? What difference does it make? Well why do ANYTHING the way you do it? To hell with the books - who needs them. LoL Walter Aviation - just another hack maintenance facility.

Isn't this a leak down test?

Please talk with your mechanic and fix your script. By removing P Leads you would make the mags hot. They are grounded by the P Leads to turn them off. Removing one lug from every cylinder will make the engine safe to turn the prop.

I like to run an air hose up into a cowled up engine to a cylinder and when someone walks by I juice it . The prop spins and they jump around like a chicken shit. Hahahaha.

A simple mistake with profound consequences. Grounded mag = no spark. Get it right....please.

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