andrewbutler
Member
Hello All,
I recently had the the Christen inverted oil system in my RV7 EI-EEO, IO-360, MT 3 Blade CS prop tested for the first time in inverted flight. The aircraft has 100 hours.
Everything was perfect. When rolled back to normal flight, the oil pressure dropped significantly to around the 10 PSI mark. Prop sped up to 2700 and the power had to be retarded to avoid overspeed. The low power setting resulted in a gradual lost of height, and the pilot decided to pull a few high G manoeuvres with what was left of altitude before landing. When he did this, the Oil pressure came back up to normal. We figured that the ball bearings in the Christen Valve (the one on the firewall) had become stuck in "inverted" mode somehow and then had seated themselves correctly during he high g manoeuvres.
To check for possible engine damage and clean out the Christen Value, I changed and inspected the oil filter, pulled the Christen valve to check the innards and inspected the sump oil screen. All was perfect, except that the strainer contained two (relatively) large pieces of blue anodised strips of aluminum. They appeared to be identical in nature. My inspector reckons these are what caused the Oil pressure drop by interfering with with the seating of the large ball bearings in the Christen valve but has no clue what they might be and where they originated. When the blockage was cleared the pieces would have immediately passed into the sump to be captured by the Oil strainer. No other material of any kind was was present in the system.
See here for photos:
Has anyone got any idea where in my oil system these may have come from and are they swarf or are they functional?
Thanks for your help.
Andrew Butler
RV7 EI-EEO
Meath, Ireland,
I recently had the the Christen inverted oil system in my RV7 EI-EEO, IO-360, MT 3 Blade CS prop tested for the first time in inverted flight. The aircraft has 100 hours.
Everything was perfect. When rolled back to normal flight, the oil pressure dropped significantly to around the 10 PSI mark. Prop sped up to 2700 and the power had to be retarded to avoid overspeed. The low power setting resulted in a gradual lost of height, and the pilot decided to pull a few high G manoeuvres with what was left of altitude before landing. When he did this, the Oil pressure came back up to normal. We figured that the ball bearings in the Christen Valve (the one on the firewall) had become stuck in "inverted" mode somehow and then had seated themselves correctly during he high g manoeuvres.
To check for possible engine damage and clean out the Christen Value, I changed and inspected the oil filter, pulled the Christen valve to check the innards and inspected the sump oil screen. All was perfect, except that the strainer contained two (relatively) large pieces of blue anodised strips of aluminum. They appeared to be identical in nature. My inspector reckons these are what caused the Oil pressure drop by interfering with with the seating of the large ball bearings in the Christen valve but has no clue what they might be and where they originated. When the blockage was cleared the pieces would have immediately passed into the sump to be captured by the Oil strainer. No other material of any kind was was present in the system.
See here for photos:
Has anyone got any idea where in my oil system these may have come from and are they swarf or are they functional?
Thanks for your help.
Andrew Butler
RV7 EI-EEO
Meath, Ireland,
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