Buchanan Field Airport, Concord, CA

During an emergency response to a roadside accident site, the helicopter experienced an in-flight collision with a tree that resulted in a main rotor strike. The Director of Flight Operations reported that the pilot had chosen a landing spot that had a tree on the southwest (SW) side of the road and a tree on the northeast (NE) side of the road. As the pilot came to a hover over the landing site, he was looking left and forward up the road to confirm that the area was secure. As he was looking toward the left front, he heard a discernable noise change from the rotor system, although there was no change in aircraft handling or any abnormal instrument indications. He looked to the right and observed that he was closer to the NE tree than he wanted to be. He then observed a broken branch on the NE tree. After a normal shut down, a visual inspection showed damage to the outer three to five inches of the trailing edge of the three main rotor blades.
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The pilot reported that the tower informed him the winds were from 250 degrees at 25 mph with gusts up to 30 mph. He aborted his first approach to runway 19R. On the second approach, he had "good rudder and aileron control at the 80 mph approach speed." At approximately 40 feet above ground level (agl), he encountered "a strong wind shear" and the airplane dropped to an altitude of 10 feet agl. The pilot added power and landed the airplane on the runway. At that time, a "very strong gust of wind" lifted the right wing and pushed the airplane towards the left side of the runway. The pilot attempted to regain control, however, he was not successful, and the airplane continued to the left "into a ground loop off of the runway." The nose landing gear collapsed, and the airplane came to rest nose down. The recorded winds at the airport near the time of the accident were from 260 degrees at 24 knots with gusts to 30 knots.
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While on an instrument approach for landing, the local tower air traffic controller observed on the BRITE radar repeater scope that the airplane passed the outer marker (OM), 600 feet below the permissible crossing altitude. The controller issued a low altitude alert to the pilot and cleared him to land. The controller also reminded the pilot that the minimum descent altitude for the Localizer Directional Aid (LDA) approach was 440 feet, and provided instructions for the missed approach. At that point the pilot reported that he had the airport in sight and acknowledged the landing instructions. The controller again cleared the pilot to land on the prescribed runway for the instrument approach, and the pilot acknowledged the landing clearance. Shortly thereafter the controller instructed the pilot to execute the missed approach as the radar track showed that the airplane was off course. The pilot was instructed to initiate a climbing left turn to the VOR. The pilot said he had the airport in sight and that he saw one of the cross runways and wanted to land. The controller told the pilot that circling to that runway was not an authorized procedure for the LDA approach and again instructed the pilot to perform the missed approach. A witness stated that he was working on a storage container, about 50 feet in height, when the airplane passed overhead. He estimated the airplane to be about 50 feet higher than the storage container. The airplane made a turn westbound and the witness looked away for a second. When he looked back the airplane was in a nose and left wing down attitude and then it impacted the ground. Another witness located on the airport's north-northeast corner also observed the airplane flying toward the airport. He reported simultaneously hearing the engine power up and observed the left wing stall prior to it impacting the ground. Both witnesses reported that they did not hear anything wrong with the engine. Examination of the airframe, power plant, and propeller revealed no mechanical anomalies that would have precluded normal operation. Internal damage signatures in the engine and propeller were consistent with the production of significant power at the time of impact. A review of the weather in the area revealed that while light rain and mist were occurring near the accident site, no meteorological phenomena existed that would have adversely affected the flight.
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The airplane landed hard and the left wing struck the runway. The student pilot reported that when he turned the airplane onto the final leg of the traffic pattern, he noticed smoke coming from a field close to the runway. The student pilot was worried about his flight visibility and the effects that the smoke would have on the handling characteristics of the airplane. Due to these concerns, he was less focused on his landing and approached the runway at too high of an airspeed. When the airplane touched down, it bounced three times and drifted to the left. He added right rudder to prevent the airplane from veering off of the runway and the airplane sharply turned to the right and the left wing struck the ground. The student pilot said that there were no mechanical malfunctions with the airplane.