Oil Filters VS Oil Screens

[GAHorn]

Cruising thru and editing my list of "favorites" bookmarked on my computer, I found this one. Thought it might provide some new fuel for controversy.

http://www.prime-mover.org/Engines/OilFilt.html

[Harold Holiman]

George,

I always liked my Orberg filter, but from your chart, it doesn't look too efficient. It is also supposed to let me know if I have any metal in the oil by the indicator light on the panel. Does that part work either?

Harold H

[N170BP]

In the "slight bit of humor category", in another
type of airplane crowd I hang with, only those
with chip detectors have had to overhaul
their engines lately <grins>.

The guys without chip detectors go 1000+ hours
before overhaul (this is a round engine).

Kinda like that old joke that says if you're faced with
a forced landing at night, turn the landing light on
as you get close to the ground. If you don't like
what you see, turn it back off.....

Bela P. Havasreti
'54 C-170B N170BP

[GAHorn]

I once had a friend drop his plane (C-175 with a GO-300-E, ...a cousin of our engines) off at my place for some lengthy mods. When I drained his oil and checked his original screen I found it pretty well contaminated with small chunks of copper, aluminum slivers, and a bit of steel or two. I knew he was going to be pretty upset, since he'd only had the airplane a short while, and that engine is not cheap to repair/rebuild. I went ahead and removed his accessories and accessory case/oil pump.
Much to my surprise there was no further evidence of destruction. I'd expected to find things pretty well contaminated with maybe some oil pump scoring or gear-tooth chipping. When I talked to him again, he surprised me by asking "WHAT oil screen?"
He'd never cleaned his screen in the 150 hours of operation he'd owned the airplane. Who knows how long before he bought it that it was cleaned? What I was seeing could have been any amount of stuff dating back to the previous overhaul/break-in for all I knew. The engine only had a little over 300 SMOH according to the logs. Since screens do not have a by-pass valve in them (another good reason to have a filter), he was lucky not to have starved his engine for oil pressure. (I know. Some folks feel that a filter that by-passes is a failure mode of the filter system. I don't feel that way. I believe an engine that clogs a filter within one oil-change period is coming apart anyway, and I'd rather it at least maintain oil flow until I can get it on the ground somewhere.)
Anyway, with enough metal in that screen removed to give cardiac-arrest, my friend's engine accessories and case were put back together and run another 400 hours with 25-hour oil changes and it never gave a problem. The oil screen was cleaned regularly after that and nothing more than carbon and an occasional sliver of aluminum was ever found. Who knows what would have happened if a chip detector had been installed.
Most chip detectors work on a simple principle. A piece of metal will short across the internal terminals lighting up the warning light. There are drain-plug-type chip detectors on the market also.
Most chip detectors I've seen have been in turbine engine installations (and helicopter transmissions) where high rotational speeds, lots of internal gearing, and immediacy of discovery and/or expense of repair is such that a chip detector is seen as a vital component. I'm not sure it's really all that useful in small recips. I'd rather have a good filter to keep that stuff from circulating, and discover it when I check the filter.
That way I'd already be on the ground when the shock occurs.

[zero.one.victor]

Cruising thru and editing my list of "favorites" bookmarked on my computer, I found this one. Thought it might provide some new fuel for controversy.

http://www.prime-mover.org/Engines/OilFilt.html

Wow,the Champion filter sure does a better job than the others,eh? How about that?
I notice that the information is credited to Airwolf,I believe their filter adapter system uses Champion filters...... How about that?
I do believe that pleated paper filters are no doubt way more effective than screens,but I tend to take comparisons like this with a grain or two of salt.

Eric

[N3243A]

According to the chart, the Continental oil screen was more efficient than the Champion filter in the 10 and 15 micron category. Granted, these are the sizes that will do the least damage but is seems funny that a screen is better than the pleated paper of the champion filter in these two cases. If anything, I would have guessed that the screens would be even less efficient than the filter as the particle size gets smaller.

[n3833v]

One reason that a screen is better than a paper filter is that the screen can't get a micro sized hole to bypass any debris. Air filters are noted for this when they get full and then any restriction gauge will show less and less restriction as the hole opens and allows dirt into the engine.

[GAHorn]

Cruising thru and editing my list of "favorites" bookmarked on my computer, I found this one. Thought it might provide some new fuel for controversy.

http://www.prime-mover.org/Engines/OilFilt.html

Wow,the Champion filter sure does a better job than the others,eh? How about that?
I notice that the information is credited to Airwolf,I believe their filter adapter system uses Champion filters...... How about that?
I do believe that pleated paper filters are no doubt way more effective than screens,but I tend to take comparisons like this with a grain or two of salt.

Eric

Champion is indeed the filter that Air Wolf claims won that test. Air Wolf does not make Champion filters. Nor is Champion the only filter that is useable on the Air Wolf system.
While your logic of questioning the motives of commercial claims is valid (I agree with you in questioning the bias)...if what they say is true, wouldn't they be foolish not to publish it? Just because they make a product that can use the superior Champion filter doesn't make their claim suspicious in itself.
In fact, there is also a spin-on filter that is better than even the Champion. It's the RAM (Waco, TX) spin on filter. The trouble is, it costs about $45 and it only comes in the long version, and it's not STC'd with the FM Enterprises/El Reno adaptor.
Their test results must have hit a nerve, however. Shortly after the results were made public, their chief competitor ADC, started offering their own version of adaptors designed to utilize the Champion spin on filters.