Don't know if this is related or not, but I have just had excellent service from our OS service centre over here in the UK. My OS46LA would be fine on the ground but die after 4-5mins of flight. A colleague at my local club had the same difficulty and sent his engine off for checking. Apparently (and this has never been confirmed) some LA series units suffer from an expansion differnetial between piston and liner causing the engine to stop after it has been running hot for a while. With this info I too sent my unit back to OS (actually looked after by Irvine who are th UK suppliers of OS engines). Within 4 days the motor was sent back with new piston and liner. The parts and labour came to £35 (approx. $50), but no charge was made. I thought this to be excellent service for an engine that had flown on and off for ~2 years. Also, check your clunk inthe fuel tank. Sometimes even the simple stuff bites us.

Chocky.