On June 10, 1999, approximately 1400 Pacific daylight time, a Bell 47G3B2A helicopter, N24MP, registered to Columbia Basin Helicopters Inc. of Pendleton, Oregon, collided with terrain while performing a 14 CFR 133/14 CFR 137 external-load agricultural aerial application flight in or near Pendleton, and was substantially damaged. The commercial pilot-in-command, who was the aircraft's sole occupant, was not injured. Visual meteorlogical conditions existed and no flight plan had been filed for the flight, which departed from the job site in or near Pendleton. At the time of the accident, the helicopter was performing agricultural operations utilizing an external bucket to drop dry fertilizer. The pilot reported that while taking off after refilling the fertilizer bucket, the external load cable to the bucket became entangled with the auger of the fertilizer truck. The pilot reported that he attempted to release the load, but that the quick-disconnect hydraulic lines did not release. The pilot reported that while attempting to get the helicopter to the ground, he had a blade strike. The helicopter subsequently impacted the ground. The pilot expressed a belief to an FAA inspector assigned to investigate the accident that "because the hydraulic lines were routed over the skid or cross tube the helicopter was thrown out of lateral C.G. when the hydraulic lines failed to disconnect properly." According to the FAA inspector, the pilot further stated to him that "during conversations with other industry folks regarding his accident, he learned that routing lines over the skid or cross tube is a known problem and that the fix is to route the lines down the release hook and cable...." Subsequent investigation revealed that the hydraulic pump and lines involved were approved as part of FAA Supplemental Type Certificate (STC) SH891NW for installation of a Simplex model 5600 spray system, which according to FAA aircraft records was installed on the accident helicopter on January 15, 1993. However, the accident helicopter was not configured with the Simplex spray system at the time of the accident. Despite repeated requests, the operator did not furnish any substantiation of FAA approval of the external bucket installation to FAA investigators. The FAA aircraft registry records on the accident helicopter also contained no record of FAA approval of the external bucket installation. The pilot, who held a commercial pilot certificate with rotorcraft-helicopter rating and private privileges for single-engine land airplanes, reported he had 650 hours of single-engine airplane time, but did not provide any information to the NTSB regarding his total pilot time or helicopter time. The pilot reported that his most recent biennial flight review was conducted on March 3, 1998, in a Cessna TU206.