SARCO,
I know nothing about the oil leak, I have emailed folks to find out. Stand by, please.
Regarding the aux lube systems in the 61, it is only for the high speed inputs, which are at 18,000 rpm, and are just bronze sleeve bearings. They fail utterly in about 30 seconds if not lubed, and usually result in dual cut shafts (autorotation) and possibly a fire. The ports for the sleeves were the last ports in the oil system, and therefore were starved if anything happened upstream of them (blockage or a jet failing to full flow.)
For the EC 225, the water/glycol aux lube was needed to certify the box because the transmission has so many old style lube lines snaking over its surface, each used to port the oil around the outside of the transmission to feed all the internal jets. This is 1960 design, most manufacturers dropped it 20 years ago. These external failure points, dozens of them, are judged by the JAR to be irredeemable as leak points, so the aux system had to be used.
The 92 has only two external lines, going to and from the cooler. These are protected by the indicator/isolation system and deemed by the JAR/FAR folks as fully compliant with the regulation as to oil system protection. All the other oil transmittal passages are part of the internal gearbox, immune from mechanic's feet and bad threads on line fittings and the like. The probability of needing the aux lube system was deemed an order of magnitude better than the older design that the 225 has.
Since these two lines might create a leak, the oil level is monitored by an oil level system, and any leak is indicated to the pilot, who then isolates the transmission from the cooler. The fly home is much more than 30 minutes, the test showed that the box allows flight at hot day for over 3 hours.
The rules for protecting a gearbox are the same for the intermediate and tail boxes, which on the 225 and the 92 are deemed compliant without any aux lube system. Remember, the consequences of such a failure are the same in every helo.
To advocate that another helo is not satisfactory for this logic while depending on it for your helo is a little duplicitous, frankly, or shows some ignorance about helicopter engineering.