Aviation Accident Summaries

Aviation Accident Summary LAX93FA369

WILDOMAR, CA, USA

Aircraft #1

N40049

ROBINSON R22 BETA

Analysis

WITNESSES HEARD TWO BANG NOISES FOLLOWED BY THE HELICOPTER SHEDDING DEBRIS. THE HELICOPTER THEN BEGAN TO SPIN TO THE RIGHT, AND DESCENDED UNCONTROLLED UNTIL COLLIDING WITH THE GROUND. THE TAIL ROTOR GEAR BOX, TAIL ROTOR BLADES, AND VERTICAL AND HORIZONTAL STABILIZER SEPARATED BEFORE THE HELICOPTER IMPACTED THE GROUND. THE LEFT DOOR OF THE HELICOPTER WAS REMOVED FOR THE FLIGHT. AN ALUMINUM KNEE BOARD, BELONGING TO THE PILOT, WAS FOUND OUTSIDE THE HELICOPTER NEAR ONE OF THE TAIL ROTOR BLADES. IT EXHIBITED IMPACT DAMAGE AND PAINT TRANSFER CONSISTENT WITH THE COLOR OF THE TAIL ROTOR BLADES. THE TIP OF ONE OF THE TAIL ROTOR BLADES EXHIBITED DAMAGE ON THE LEADING EDGE CONSISTENT WITH STRIKING A METALLIC OBJECT.

Factual Information

History of the Flight On September 24, 1993, at 1454 hours Pacific daylight time, a Robinson R-22 Beta, N40049, collided with level terrain after experiencing an inflight loss of control near Wildomar, California. The pilot was conducting a visual flight rules cross country instructional flight to French Valley Airport, Murrieta, California. The helicopter, operated by U.S. Air School, Brackett Airport, La Verne, California, was destroyed by impact forces. The certificated private pilot and a student pilot/passenger were fatally injured. Visual meteorological conditions prevailed at the time. The flight originated at the Brackett Airport, La Verne, California, about 1430 hours. The operator reported that the first pilot was conducting the flight to accumulate the necessary cross country flight experience to qualify for a commercial pilot certificate. The student pilot was in the helicopter for an orientation to cross country flying. The Riverside County Sheriff's Office reported witnesses heard two bang noises followed by the helicopter shedding debris. The helicopter was about 200 feet above the ground at the time. The helicopter then began to spin to the right, and descended uncontrolled until colliding with the ground. An aluminum knee board belonging to the private pilot and an aeronautical sectional chart used for cross country navigation were found within 50 feet of one of the tail rotor blades. The aeronautical sectional chart displayed a course line from the Brackett Airport to the French Valley Airport. The accident location was on the course line drawn on the chart. Crew Information First Pilot The first pilot was seated in the right seat. The first pilot held a private pilot certificate with an airplane, single engine land and a rotorcraft-helicopter rating. The most recent third class medical certificate was issued to the pilot on July 27, 1992, and contained no limitations. According to the first pilot's logbook, her total aeronautical experience consists of about 185 hours, of which 108 were accrued in the Robinson R-22 Beta. In the preceding 90 and 30 days prior to the accident, the logbook lists a total of 45 and 28 hours respectively flown. All of the 28 hours logged in the preceding 30 days were flown in Robinson R-22 helicopters. Second Pilot The second pilot was seated in the helicopter's left seat with the left door removed. According to the second pilot's training records, maintained by the operator, his total aeronautical experience consists of about 5 hours, all of which were accrued in the Robinson R-22 Beta. The second pilot had not applied for a student pilot/medical certificate. Wreckage and Impact Information The helicopter came to rest about 100 feet east of Interstate 15 about 1/10 of a mile north of the Clinton Keith Road exit overcrossing. The nose of the helicopter was oriented in a northerly direction. The helicopter's landing gear was collapsed. The fuselage was resting on its right side. The mast was tilted to the right about 35 degrees from level with the ground. The engine was resting on its right side at an angle similar to the main rotor mast. The exhaust system was bent upward. The drive belts were intact and found loose. One of the main rotor blades was broken about 18 inches from the hub. The outboard section was found by the tailboom. The other rotor blade was still attached to the rotor hub. It was bent opposite to the direction of main rotor rotation with its outboard portion touching the ground. There was no evidence of either of the main rotor blades contacting the tailboom or windshield canopy. Fragmented pieces of the windshield were found directly in front of the helicopter's point of rest. The majority of the fragments were to the right of the wreckage longitudinal centerline. Some fragments of both the right and left windshield remained attached to the windshield center post. The tail rotor gear box, tail rotor blades, and vertical and horizontal stabilizer were separated. The vertical and horizontal stabilizer and pieces of the tail rotor blades were found about 500 feet northwest of the helicopter wreckage in the area where the witnesses reported seeing the debris fall. The tail rotor gear box, tail rotor hub, and one tail rotor blade were not found. Drive train continuity was established from the engine to the main rotor system and to the point on the aft tailboom where the vertical and horizontal stabilizer mount. Control continuity was established for the cyclic, collective, and engine controls. Continuity of the tail rotor pitch controls was established from the pedals in the cockpit to the separation point on the tailboom where the tail rotor drive was also broken. The tail rotor pedals were found in the full left pedal position. The collective was found mid-range position. The throttle was jammed. Examination of the linkage established that it was also in a mid-range position. The left door of the helicopter was not found at the accident site. The left door was reported to have been removed for the flight and was at the Brackett Airport. The right door was found next to the fuselage at the accident site. It should be noted the tail rotor is mounted on the left side of the tail boom on the Robinson R-22 Beta. The knee board exhibited impact damage and paint transfer consistent with the color of the tail rotor blades. The tip of one of the tail rotor blades exhibited damage on the leading edge. The private pilot was found in the right seat of the helicopter with the seat belt/shoulder harness still fastened. The student pilot was found to the right of the left seat with his feet above the floor forward of the left seat cushion. The student pilot's seat belt buckle appeared to be bent. There was metal fuzz on the seat belt tab in the area where it engages the buckle. Medical and Pathological Information Postmortem examinations were conducted by the Riverside County Coroner's Office on September 27, 1993, with specimens retained for toxicological examinations. The postmortem examination on the pilot disclosed no evidence of any conditions or disease which would have detracted from the pilot's ability to fly the helicopter. The toxicological examinations were conducted by the Federal Aviation Administration, Civil Aeromedical Institute, Oklahoma City, Oklahoma. The results of the toxicological analysis revealed negative results for routine drug and alcohol screens. Additional Information Wreckage Release The wreckage was released to the representatives of the owner on September 24, 1993.

Probable Cause and Findings

THE FAILURE OF THE TAIL ROTOR BLADE AFTER BEING STRUCK BY THE PILOT'S KNEE BOARD, AND THE FAILURE OF THE PILOT TO ADEQUATELY SECURE THE KNEE BOARD WHILE IN FLIGHT.

 

Source: NTSB Aviation Accident Database

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