At 0953 Pacific time, an amateur-built Thorpe T-18 rolled over and landed inverted at Compton/Woodley Airport, killing the pilot. The airplane had been flying for about 40 minutes, making several takeoffs and landings. The pilot of a Robinson helicopter, also in the pattern, said the Thorpe pilot was announcing his intentions on the common frequency. Meanwhile, an EC-135 helicopter called, reporting two miles east of the airport for a straight-in approach to runway 25R. The Robinson pilot said the other helicopter and the Thorpe arrived at the runway at about the same time. The Robinson pilot said he transmitted a warning to the pilots to watch out. When the two aircraft were about 100 feet apart and at a height of about eight feet, the Thorpe turned right to avoid the EC-135, rolling inverted and landing on the canopy. The EC-135 pilot said he heard the Robinsons transmissions but not the Thorpes.