Alan Erickson
Active Member
Folks, I'm getting ready for first flight, but it's on hold 'til I can work out an oil pressure glitch. I could use some more brains on this one.
Summary:
Pressure on startup goes to 45psi at 650rpm (great!). However, even with a full runup I don't get over 50psi.
System:
* Aero Sport Power (ASP) IO-360-M1B6 with Raven inverted system
* c/s prop
* standard oil pressure tap just inboard of top stbd engine mount
* steam gauge (temporarily teed in) corroborates AFS-2500 sensor
* straight 50 mineral oil
* ASP logs indicate 70psi during stand runs
* I haven't knowingly changed pressure relief valve (PRV) adjustment
* oil appears, smells normal (~25min total runtime). no debris when drained and examined.
* I pre-oiled engine prior to first start, injecting a few qt at top stbd fwd galley plug
* no leaks in system
* system quite full: up to 8qt on stick with inverted plumbing full and prop having been cycled
* all hoses eyeball- and hand-checked: no constrictions. All installed per Raven instructions
Symptoms:
* no-start cranking = 20psi
* 47psi @ 650rpm within ~1sec
* warms at seemingly normal rate
* constant 50psi at > ~800rpm (tested briefly to 2700 during prop bal)
* no change in psi as temperature rises
* prop cycles normally at > ~950rpm. temporary ~5psi drop when prop pulled back, with return to 50psi within seconds
So...any thoughts?
Here're mine:
* PRV maladjustment seems unlikely: ASP saw/adjusted to 70psi (adjustment to reduce pressure evident from lack of engine paint on ~2 threads of adjustment screw). why would it have changed? Aging spring possible; engine built 2004. Possible accidental adjustment? Would 2-3 threads account for 20psi? (rumor sez it's more like 3psi per turn)
* pump intake restriction seems unlikely: if present, I wouldn't think I'd see great pressure at idle
* others have noted oil pressure issues resulting from air leaks on the suction side (e.g. inverted system). I've not developed a clear picture of the expected symptoms in that case - can anyone provide some experience here? General principles lead me to think that a different set of symptoms would present for this case.
* air-locked or dirty PRV (per Lyco troubleshooting guide) seems like a good direction to explore, especially given that I pre-oiled via the galley and could have introoduced air or debris. Your thoughts? Can anyone explain exactly how the PRV can get air-locked?
Thanks for any input!
Summary:
Pressure on startup goes to 45psi at 650rpm (great!). However, even with a full runup I don't get over 50psi.
System:
* Aero Sport Power (ASP) IO-360-M1B6 with Raven inverted system
* c/s prop
* standard oil pressure tap just inboard of top stbd engine mount
* steam gauge (temporarily teed in) corroborates AFS-2500 sensor
* straight 50 mineral oil
* ASP logs indicate 70psi during stand runs
* I haven't knowingly changed pressure relief valve (PRV) adjustment
* oil appears, smells normal (~25min total runtime). no debris when drained and examined.
* I pre-oiled engine prior to first start, injecting a few qt at top stbd fwd galley plug
* no leaks in system
* system quite full: up to 8qt on stick with inverted plumbing full and prop having been cycled
* all hoses eyeball- and hand-checked: no constrictions. All installed per Raven instructions
Symptoms:
* no-start cranking = 20psi
* 47psi @ 650rpm within ~1sec
* warms at seemingly normal rate
* constant 50psi at > ~800rpm (tested briefly to 2700 during prop bal)
* no change in psi as temperature rises
* prop cycles normally at > ~950rpm. temporary ~5psi drop when prop pulled back, with return to 50psi within seconds
So...any thoughts?
Here're mine:
* PRV maladjustment seems unlikely: ASP saw/adjusted to 70psi (adjustment to reduce pressure evident from lack of engine paint on ~2 threads of adjustment screw). why would it have changed? Aging spring possible; engine built 2004. Possible accidental adjustment? Would 2-3 threads account for 20psi? (rumor sez it's more like 3psi per turn)
* pump intake restriction seems unlikely: if present, I wouldn't think I'd see great pressure at idle
* others have noted oil pressure issues resulting from air leaks on the suction side (e.g. inverted system). I've not developed a clear picture of the expected symptoms in that case - can anyone provide some experience here? General principles lead me to think that a different set of symptoms would present for this case.
* air-locked or dirty PRV (per Lyco troubleshooting guide) seems like a good direction to explore, especially given that I pre-oiled via the galley and could have introoduced air or debris. Your thoughts? Can anyone explain exactly how the PRV can get air-locked?
Thanks for any input!