WPR10LA347

After extending the landing gear, the pilot confirmed that the green landing gear light was illuminated, which indicated that the landing gear was down and extended. A short time later, a complete electrical failure occurred, and the landing gear collapsed during the landing roll. A postaccident examination of the airplane revealed that the landing gear was partially extended, the main landing gear struts were folded inboard, and the nose landing gear was folded up into the wheel well. All wiring to the landing gear motor, gear indicator and limit switches and control circuits were inspected and exhibited no anomalies. However, during the examination, wiring was found pinched and tangled in the left main landing gear actuating arm. It could not be determined if this wire contributed to the electrical failure or if it caused a possible false activation of the gear limit switches, which then falsely illuminated the landing gear light.

On July 2, 2010, about 1930 Pacific daylight time, a Beech E-55, N3644A, was substantially damaged following a landing gear collapse during landing roll out at the McCarran International Airport (LAS), Las Vegas, Nevada. The airline transport pilot and his four passengers were not injured. Visual meteorological conditions prevailed for the cross-country flight, which was operated in accordance with 14 Code of Federal Regulations Part 91, and a flight plan was not filed. The flight departed the Santa Monica Municipal Airport (SMO), Santa Monica, California, about 1730. In a statement submitted to the National Transportation Safety Board investigator-in-charge (IIC), the pilot reported that upon entering the traffic pattern to land and while extending the landing gear, the airplane started vibrating. The pilot stated that he confirmed that the "GREEN" light was on, which indicated to him that the landing gear was down and extended; a post accident examination of the landing gear system revealed that the color of the gear down light is BLUE. The pilot reported that he also confirmed that the red arrow indicator was pointing down, which indicated the landing gear was down and extended. The pilot further reported that "all of a sudden” he lost the complete electrical system, which included two GPSs, “all gauges” and radio communications, after which he squawked transponder code 7600. The pilot stated that after turning final [approach] he tried to add full flaps but they did not extend. The pilot added that he maintained landing speed and touched down on the runway, and during the initial roll out everything appeared normal. The pilot added further that “all of a sudden” the left wing dropped, followed by the right wing dropping. The pilot reported that the airplane then skidded on the runway and came to a full stop. The airplane sustained substantial damage to the lower fuselage area. Both propellers and the main landing gear doors were also damaged. At the request of the IIC, a postaccident examination of the airplane was conducted by a Federal Aviation Administration (FAA) aviation safety inspector, assisted by a certified FAA airframe and powerplant (A&P)mechanic. The examination revealed that the landing gear was found partially extended. The main landing gear struts were folded inboard with the landing gear tires contacting the partially open inboard landing gear doors. The inboard landing gear door outboard edges were rubbed from contacting the runway surface. The nose landing gear was folded up into the wheel well, and the nose landing gear extend rod was separated from the landing gear actuator nose landing gear extend/retract arm, which is located at the base of the landing gear actuator. The main landing gear actuator extend/retract bellcrank arms were positioned at an intermediate landing gear extend/retract position. The FAA inspector also reported that while the landing gear DOWN indicator was operational, its exact position could notbe determined prior to the aircraft landing. In a subsequent and more detailed examination of the airplane conducted by both the FAA inspector and the A&P mechanic, it was revealed that all wiring to the landing gear motor, gear indicator and limit switches and control circuits were inspected for integrity and routing, with no anomalies noted. There was wiring that was observed to be pinched and tangled in the left [main landing] gear actuating arm, which was inspected as it routed through the left side wall and up to the circuit breaker panel and cockpit switches. The inspection also revealed that the wiring could not have affected the wiring behind the circuit breaker panel. The mechanic stated that the pinched wire could possibly have gotten tangled in the left gear rod end during operation of the landing gear. The mechanic stated further that it was possible that the wire could have activated the down micro switch prematurely, turning off the landing gear motor, turning on the BLUE down light and disabling the gear warning horn, when in fact the gear was not all the way down, which may have caused the gear to collapse on landing. A Hawker Beechcraft engineer reported that the landing extend limit switch and the landing gear extend position switch are mounted on top of each other, and that activation of one by the entangled wire could have activated both switches. The examination revealed that no obvious problems or defects were found that could have lead to a mechanical failure and collapse of the landing gear. Further, with respect to the wire that was found lodged between the main landing gear gearbox arm and the left main actuating rod end, it is unknown if this wire might have contributed to a possible false activation of the gear limit switches. The examination concluded that no determination could be made as to when the wire may have broken, or to the exact sequence of events that led to the wire becoming lodged between the main landing gear gearbox arm and the left main [landing] gear rod end. This condition was not observed until after the airplane had been relocated to a secured location off of the active runway where the airplane came to rest.