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After my PSRU input shaft oil seal leak/failure in my RV-3B I decided to do the same mods I did on my RV-4 PSRU.
1) Enlarge the rear drain to 1/2" NPT elbow to 3/4" hose barb. 3/4" ID hose to 1/2" NPT into rotor housing.
2) Drill and tap 1/4" NPT into side of the above brass elbow with AN6 line to PSRU front drain.
3) Add vent on top of PSRU rear ring/spacer -- vent to same point as "crankcase vent" -- oil filler tube.
4) Cut small groove in PSRU mount plate under PSRU input shaft thrust bearing race to allow oil accumulating near seal to drain.
It is possible that the seal failed due to restricted "crankcase vent" line, but after reviewing the "Venting the Reduction Drive" thread here starting 6 May 2019, I decided I might as well do these mods now that I anyway have everything apart for seal replacement. Looks like it would lower PSRU oil temperature by not having gears churning oil in the PSRU full with oil.
Even though I tried to catch alum shavings from drilling up and tapping the 1/2" NPT hole in the rotor housing with grease and a rag I still found pieces in there. I guess I need to drain and filter the (brand new) oil and flush with mineral spirits or old gas until no more pieces comes out the oil pan drain. I really, really do not want to remove the newly installed and sealed oil pan. Anyway waiting for new brass fitting to arrive. Drilled 9/16 not 7/16 for the 1/4" NPT thread :(
First flight of my RV-3B in 5 years any week now ...
Finn
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