On March 13, 2003, at approximately 1205 mountain standard time, a Piper PA-28R-200, N16438, was substantially damaged when it collided with terrain during a forced landing near Delta, Colorado. The private pilot and his passenger were not injured. Echo Aviation Partnership, LLP, was operating the airplane under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local maintenance test flight that originated at approximately 1155 from Montrose, Colorado. The pilot had not filed a flight plan. According to the pilot, the airplane's engine had just been overhauled, and this was the initial flight test. He said the takeoff/departure was normal, and "the airplane climbed to a cruise altitude of 8,000 feet with no difficulty." Eight minutes into the flight, the pilot noted the engine's speed (revolutions per minute [rpm]) increase to red line. He then adjusted the propeller control to compensate for the high engine rpm. Reduction of the engine's rpm was followed by the engine stopping. The pilot then told the pilot-flying that he had control of the airplane. He then proceeded to shut the fuel off, and selected a field for the forced landing. He stabilized the airplane at best glide airspeed, and subsequently the landing gear automatically deployed. The pilot selected a secondary landing site, which was on the back side of a hill. The airplane bounced several times while "rapidly" descending down the hill. The airplane came to rest with the nose gear and left main gear collapsed. Additionally, the left wing spar and firewall were bent. A postaccident examination of the engine showed that one oil pressure fitting in the engine accessory drive case had not been capped.