Mailing List flyrotary@lancaironline.net Message #15991
From: David Staten <Dastaten@earthlink.net>
Subject: Re: [FlyRotary] Re: oil analysis results (140k attachment)
Date: Tue, 25 Jan 2005 08:52:15 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

May I respectfully suggest that Oil Analysis in this setting just really isnt the right test for what you are looking for? Oil analysis is going to look for trace/contaminants as wear indicators. You establish a baseline for your engine by submitting samples on a regular basis and look for gradual slow changes. This would be akin to a patient going to the doctor annually for a checkup (medical example cause thats what I do for a living - ICU nurse/paramedic).
 
In your event, you suffered a catastrophic failure in the oil cooling system and your oil went from the pan, to the cooler and OUT of the engine before it could even pick up any contaminants or "wear indicators" related to the engine failure event. The oil that remained in the pan was unable to be picked up and pumped overboard, so it was representative of "before failure" conditions. Using the medical example, this would be akin to the patient dying from some traumatic, unforseen event, then sending the body to the family doctor for yet another routine checkup and saying "why didn't you warn me!!"
 
Morbid.. but I hope it explains the reason the results are underwhelming.
 
I think its interesting the analysis comments about fuel and fuel contamination. I think this reinforces the concept that the unburnt 2 cycle oil (and unburnt fuel) that gets deposited on the trochoid walls gets scraped off and added to the oil pan oil, and would be EXPECTED in engines running premix or 2-cycle injection reservoirs.
 
Oil analysis is a useful tool, but you shouldn't depend on it to show acute changes.. rather general wear trends. I can't think of anything in oil analysis that would have said "Your oil cooler will say 'I quit' within the next oil change cycle.
 
Dave Staten
 
I believe that routine oil analysis can probably be of some value as far as trends might go, but I'm extremely under whelmed by the results of this test.  It just seems to me that something should have been screaming "damage", but clearly it isn't. 
 
Cheers,
Rusty (maybe my rotors were calcium coated)



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