On January 21, 1995, at 1030 Pacific standard time, a Piper PA31- 350, N36PB, collided with a tree while flying the NDB approach to La Grande, Oregon. Instrument meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The airplane was substantially damaged and the airline transport pilot was not injured. The flight had originated from Pendleton, Oregon, on January 21, 1995, at 0945 and was being repositioned to La Grande. In a written statement, the pilot reported that prior to departing from Pendleton, he checked the weather for both La Grande and Baker City and decided to go as the weather seemed to be improving. During the flight, Seattle Center advised the pilot that La Grande was reporting 300 feet overcast and two miles visibility. At this time, the pilot stated that he began to set the radios for the Non Directional Beacon (NDB) approach. The pilot set the Automatic Direction Finder (ADF) to 296 and listened for the Morse code identifier. The pilot stated that he didn't notice much change in the needle direction and the Morse code identifier was weak and scratchy. The pilot stated that he didn't pay much attention to this, since he was still a distance away from the facility. As the flight got closer to La Grande, the pilot stated that the ADF needle indication was improving, but not acting normal and the identifier was still weak. The pilot decided to back-up the ADF by utilizing the Pendleton and Baker VOR's to identify the NDB. The pilot was then cleared for the NDB approach and the pilot started his descent from 9,000 feet. When the aircraft passed the NDB, the pilot stated that he didn't have a good clear station passage, but that the needle did eventually point behind the airplane. The pilot then started the procedure turn and descended to 7,200 feet. When the pilot felt that he was established on the inbound heading of 168 degrees, he descended to 5,400 feet. The pilot extended the landing gear and approach flaps in preparation for landing. The pilot then called La Grande UNICOM for the airport advisories. The pilot stated that he was still above the fog layer when he passed the NDB and that he still didn't have a good signal. The airplane entered the fog at 4,500 feet and the pilot leveled off at 4,000 feet. The pilot stated that two minutes after passing the NDB station, looked down to find the airport. Instead, the pilot stated that he saw trees and immediately thereafter, felt the airplane hit something. The pilot then added full power and initiated the missed approach. The pilot then called Seattle Approach and asked for clearance to Baker City, where a landing was made without further incident. The airport elevation at La Grande is 2,714 feet. The pilot stated that he never descended below 4,000 feet, the minimum descent altitude. The terrain to the north of the airport that is under the approach path, is a valley at or near the same elevation as the airport. The terrain to the east and west of the airport rises to approximately 6,000 feet. It could not be determined where the collision occurred. Post crash inspection of the airplane, by the Director of Maintenance at Airpac Airlines, revealed evidence that the airplane had collided with a tree(s). The La Grande Airport is owned by Union County and the airport facilities are monitored 24-hours a day by the La Grande Police Department. The Police Department reported that at 0200 hours on January 21, 1995, the alarm that the NDB was out of service sounded. The Police Department dispatcher notified McMinnville Flight Service Station (FSS), that the "Beacon" was out of service, (meaning that the NDB was out of service). The Specialist at the FSS, however, interpreted "beacon" as meaning the "rotating beacon" on the airport was out of service. Seattle Center was not notified that the NDB was out of service and no Notice to Airmen (NOTAM) was issued. The company contracted by Union County to maintain the NDB facility reported that the facility shut down due to a build-up of ice on the antenna. The equipment is designed to automatically reset itself for 30 seconds every hour. If the reset mode is not accomplished after 30 seconds, the facility shuts down for another hour and the reset is then tried again. The technician monitoring the system stated that the automatic reset mode was functioning properly. When the ice on the antenna melted, the facility became operational on January 22, 1995 at approximately 1400 hours. The technician stated that if the identifying signal was transmitting, it may have been during the 30 second reset mode. The technician was not sure what the pilot was identifying in between the reset mode. The Airmen's Information Manual (AIM) states that the radio beacons are subject to disturbances that may result in erroneous bearing information. Disturbances which affect the ADF bearing also affect the facility's identification. The AIM states that "Noisy identification usually occurs when the ADF needle is erratic. Voice, music or erroneous identification may be heard when a steady false bearing is being displayed. Since ADF receivers do not have a 'flag' to warn the pilot when erroneous bearing information is being displayed, the pilot should continuously monitor the NDB's identification."