Page:NTSB Aircraft Accident Report, United Airlines Flight 389.pdf/21

 The No. 1 VHF communications receiver and control selector were found tuned to 129.35 mcs., an ARINC (company radio) frequency for Chicago. The No. 2 VHF communication control selector was found set at 119.0 mcs., the frequency of the O'Hara Approach Control on which the flight had been communicating. The No. 2 receiver was not recovered.

The recovered wiring of the essential electrical power panel had no evidence of overheating, arcing, or burning. Examination of the three main engine generator feed cables and the male portions of the Nos. 1 and 3 generator connectors revealed no evidence of arcing, overheating, sooting, or burning. The generator control panel switches were set for normal operation. The essential power switch was set for the No. 3 engine, normal for UAL, and the No. 3 engine bus tie relay was in the "closed" (normal) position. The two constant speed drive units recovered from the Nos. 2 and 3 engines were found in the connected position. The electrical actuator for tail skid positioning was extended approximately 3 inches which corresponds to the skid retracted position.

Examination of the flight control systems showed the aileron components were damaged with the aileron centering mechanism in neutral (centered). The aileron power control unit and linkage were intact, although broken away from the structure. The mechanical linkage was in a 5 degree left aileron down position. The power unit was separated from the mechanical unit and the broken ends of the cable strands were necked down in the area of separation. The aileron trim indicator cable drum