Can an owner do a compression check?

vince said:
Just reading this thread makes me happy I don't have to own a plane or buy one. I will just keep renting. Sounds like the planes I could afford who knows what kind of monkey has been wrenching on it. I just shudder to think of buying a plane that has been "maintained" by some of the posters on this thread!
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How do you expect to buy a decent argument without a couple of quotes.
https://www.youtube.com/watch?v=kQFKtI6gn9Y
 
jesse said:
lol, and how exactly is renting a solution for your over-the-top irrational fears?
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Easy, by renting only from places that I've checked out and feel good about their level of maintenance.

If I had any suspicion that a plane I wanted to buy was maintained by someone not qualified I wouldn't want anything to do with it. Sorry if that offends many people here since I know many of you are doing this. Let's just hope you know what you're doing for your sakes. As for me, I decline to fly your clapped together contraptions as is my right and my duty to myself and my passengers.
 
vince said:
Easy, by renting only from places that I've checked out and feel good about their level of maintenance.

If I had any suspicion that a plane I wanted to buy was maintained by someone not qualified I wouldn't want anything to do with it. Sorry if that offends many people here since I know many of you are doing this. Let's just hope you know what you're doing for your sakes. As for me, I decline to fly your clapped together contraptions as is my right and my duty to myself and my passengers.
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So basically you would rather rent something knowing almost nothing about the aircrafts maintenance history and having no ability to personally inspect much of anything. You also have no idea what the last hundred pilots did to the airplane or if someone overstressd it or damaged it on the previous flight. You also have no clue what the operator has decided not to fix at the current moment in time.

Where as if you buy you can personally look over all the records back to day one and then personally hire the best mechanic in the world to inspect and disassemble it followed by you personally inspecting every single component you'd wish. Followed by you personally making sure it's maintained throughout the future. You'll also always know what happened to it on every flight. You'll always be the one deciding how it's maintained and how's it's repaired.


uhh, okay...if you'd rather blindly trust a rental operator and every pilot that rents the airplanes instead of doing it yourself then so be it.
 
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You guys make me laugh. An airplane can be damaged just by sitting on the ramp. For example, I saw a piper Cherokee parked maybe 50 feet behind a citation 560 that was getting ready to leave. When the citation increased power to just enough to begin rolling from its parking spot I saw all three struts on the Cherokee go to full extension :hairraise:,not tied down and no chalks. I though it was going to be more entertaining in a moment but luckily the parking brake kept it from rolling backward into the small plane behind it.

Airplanes outside can be damaged by many different things, gusty winds, loose tools and trash at the airport, careless pilots, careless line crews and the list goes on. Heck a spit of rain can ruin your day if fuel caps are leaky and water contaminates the fuel system.

We haven't even touched on human factors yet. Was the mechanic finished torquing all the cylinder nuts when the owner dropped by for an update? Was he finished timing the mags when the phone rang?


I've even heard of a preflight gone bad before. Be sure when you pull the strainer drain knob that the strainer stops draining when you release it. The cable could be sticky and setting u up for failure if you don't verify.
 
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I don't care who you are, you can perform compression check any time you want to.
Is it wise to enter the results in the logs? I don't know. But at least you'll know what the comps are at that moment in time. But as stated before, if you just rely on the comp check, say 74/80 what does that tell you? Why is it not 80/80? where is that air going? And why? You also need to use your ears along with the gauges, and air supply.
Why use /80 as the baseline? why not 120 or 200? Because 80 is safer than anything higher, that's why. But the ratio should be close, no matter.
Why not do leak down test on cars? Cars don't have a handle on the crank. Why not do total comp check on airplanes? because airplanes do have a handle on the crank. Either way all cylinders should read within a certian percentage of each other.
If all but on on an airplane are between 70-80, say 74, 72,76, and one oddball at 67.
or in a car at 120, 125,119, and one oddball at 100. The oddball would be suspect.
 
bluerooster said:
I don't care who you are, you can perform compression check any time you want to.
Is it wise to enter the results in the logs? I don't know. But at least you'll know what the comps are at that moment in time. But as stated before, if you just rely on the comp check, say 74/80 what does that tell you? Why is it not 80/80? where is that air going? And why? You also need to use your ears along with the gauges, and air supply.
Why use /80 as the baseline? why not 120 or 200? Because 80 is safer than anything higher, that's why. But the ratio should be close, no matter.
Why not do leak down test on cars? Cars don't have a handle on the crank. Why not do total comp check on airplanes? because airplanes do have a handle on the crank. Either way all cylinders should read within a certian percentage of each other.
If all but on on an airplane are between 70-80, say 74, 72,76, and one oddball at 67.
or in a car at 120, 125,119, and one oddball at 100. The oddball would be suspect.
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We do use leak down compression tests on cars as well, they are not pervasive by any means, but they do happen typically to help determine where the bad reading on the TCT lies by doing the same as on an airplane, listening to the breather and exhaust.
 
Also used to do "running" compression tests on cars also to determine valve condition.

Yes, pulling a plug, shorting the ignition wire for that cylinder, screwing in the compression gauge and take a reading with the engine running.

Aeromotive is so far behind automotive technology its not even funny anymore. I asked my DME while getting my A&P why technicians didn't use oscilloscopes for misfire diagnostics as peak Kv, burn time, dwell, etc, etc can be really useful information. He said that he wished (he was also an AP school administrator) he could have technology like that and agreed that aeromotive technology was woefully inadequate.
 
jaybee said:
...Aeromotive is so far behind automotive technology its not even funny anymore. I asked my DME while getting my A&P why technicians didn't use oscilloscopes for misfire diagnostics as peak Kv, burn time, dwell, etc, etc can be really useful information. He said that he wished (he was also an AP school administrator) he could have technology like that and agreed that aeromotive technology was woefully inadequate.
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There is a philosophy I think you may be missing here and it's based on simplicity rather than complexity. For instance a Magneto, you have to force it to stop working. When an aircraft engine is running you have to initiate some action to make it stop.

The other difference is that the automobile merely rolls across the ground and can only dream of taking flight.
 
I've seen pictures

obama-skeet-dukes-of-hazzard.jpg
 
obviously fake. bo and luke only used archery
 
Silvaire said:
There is a philosophy I think you may be missing here and it's based on simplicity rather than complexity. For instance a Magneto, you have to force it to stop working. When an aircraft engine is running you have to initiate some action to make it stop.
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Aye, so you have no idea what you are saying.

Not much is simpler than hooking up some clamp on leads to some spark plug wires and taking a reading(fits every model too). As stated the information given tells volumes. Combine with a four gas analyzer and I can tell you exactly what is wrong inside an engine without ever turning a bolt. ;) :yesnod:
 
I changed my oil, checked the prop track, and did a compression check. I also recorded all that in the logbook, the horror!

76/80
72/80
78/80
72/80

Signed, an Experimental owner.
 
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jesse said:
I changed my oil, checked the prop track, and did a compression check. I also recorded all that in the logbook, the horror!

76/80
72/80
78/80
72/80

Signed, an Experimental owner.
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AFAIK, anybody can maintain an Experimental aircraft and write in the logbook (not including the yearly condition inspection). IMO, it would be more informative to include the caliber of orifice used for the test. YMMV.

dtuuri
 
dtuuri said:
AFAIK, anybody can maintain an Experimental aircraft and write in the logbook (not including the yearly condition inspection). IMO, it would be more informative to include the caliber of orifice used for the test. YMMV.

dtuuri
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Indeed...which is why I would be incredibly hard pressed to buy a certified airplane. I can imagine there being a day where I would buy a certified, but it would have to be the day where I can afford to quit maintaining my own stuff and pay others to do it. Given how I keep buying toys, it's unlikely I'll be in that position any time soon :)
 
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