SANTA ANA, CA, USA
N9070N
Robinson R22
Both pilots were practicing full touchdown autorotations while in the traffic pattern. The second pilot made three successful touchdown autorotations and takeoffs. The first pilot assumed the controls after the second pilot completed the third autorotation. On final approach, the first pilot decelerated the helicopter and increased the glide angle to the runway. He then attempted to decrease the glide angle when it became evident that he was going to land short. The first pilot attempted to arrest the rate of descent, but without success. He was able to level the helicopter before it struck the ground. A ground witness said that the helicopter decelerated and then nosed over. The descent rate was between 1,000 to 2,000 feet per minute, and the main rotor rpm was at 100 percent throughout the sequence of events. The first pilot said he could not recall if the engine responded to his throttle inputs. Postaccident examination disclosed no evidence of any preexisting airframe or engine malfunctions or failures.
History of Flight On April 30, 1996, at 1800 hours Pacific daylight time, a Robinson R-22 Beta Helicopter, crashed about 20 feet short of runway 19L at John Wayne Airport, Santa Ana, California. The pilots were conducting a local visual flight rules personal flight and were practicing full touchdown autorotations. The helicopter, operated by Helistream, Inc., was destroyed. The first pilot held an airline transport certificate with rotorcraft ratings for helicopter and instruments. The second pilot held a commercial pilot certificate. Both pilots held a flight instructor certificate with rotorcraft ratings for helicopter and instruments. The first pilot received minor injuries and the second pilot sustained serious injuries. Visual meteorological conditions prevailed. The flight originated at John Wayne Airport, about 1740. The first pilot was flying the helicopter at the time of the accident. He told Safety Board investigators in a telephone interview that he was the pilot-in-command of the helicopter. He said that he and the second pilot were practicing autorotations to touch down on runway 19L. He said that the second pilot made the first three autorotations to a touchdown. After the second pilot made the third landing he assumed the controls. He reentered the traffic pattern and the local controller cleared him to make a stop-and-go landing on the numbers. While on final approach, about 500 feet above ground level, he determined that the current glide path would make him land long (beyond the numbers). He reduced the airspeed to 30 knots to shorten the glide angle. At this time he increased the main rotor rpm to 109 percent. When the helicopter descended through 300 feet agl, he nosed the helicopter over and increased the airspeed; the main rotor rpm decreased to the middle of the green arc. When the helicopter approached the airport boundary, the pilot realized that the helicopter was going to land short of the runway. The pilot applied power and up collective to arrest the descent, but without success. He said that he could not tell if the engine responded to the throttle input. When he realized that a landing was imminent, he leveled the helicopter and touched down in a level attitude. The second pilot confirmed the first pilot's statement regarding the sequence of events preceding the accident. He added, however, that he could not tell if the engine responded to the throttle input. He said that the engine out warning light did not illuminate and that the low rotor warning horn sounded just before ground contact. A pilot ground witness reported that at the time of the accident he was with his student in a Cessna 152 holding short of runway 19L at taxiway Kilo. He said he observed the helicopter on final approach. During the descent the helicopter's pitch attitude leveled off for about 4 or 5 seconds. The helicopter then nosed down and its rate of descent increased between 1,000 and 2,000 feet per minute. The helicopter appeared to level off when it was about 100 feet above ground level (agl), but the rate of descent was not arrested. The helicopter's pitch attitude increased about 5 degrees when it was about 10 feet agl. The helicopter struck the ground while maintaining this attitude. The helicopter flipped over onto its back and came to rest with the nose pointing about 180 degrees from its original impact heading and on it side. He said that the rotor rpm appeared to be 100 percent throughout the sequence of events. He also said that he did not see the main rotor blades cone upward at any time. The pilot ground witness is a current U.S. Army Reserve helicopter instructor pilot. Crew Information In addition to being the president of the company, the first pilot is the chief flight instructor for the company's certificated flight school. The pilot holds an Airline Transport Pilot certificate with rotorcraft ratings for helicopter and instruments, and several helicopter type ratings. He also holds a certified flight instructor certificate with rotorcraft ratings for helicopter and instruments. He holds an unrestricted first-class medical certificate dated August 1995. The flight hours reflected on page 3 of this report was provided by the pilot. Safety Board investigators did not examine the pilot's flight hours logbook. In addition to the flight hours, the pilot also said that he satisfactorily completed a biennial flight review (BFR) 5 months before the accident. The BFR was flown in a Robinson R-44 helicopter. The second pilot is an assigned check airman for the flight school. The second pilot holds an Airline Transport Pilot certificate with rotorcraft ratings for helicopter and instruments, and R-44 and BH-206 type ratings; the certificate is endorsed for private pilot privileges in an airplane with a single engine land rating. He also holds a certified flight instructor certificate with rotorcraft ratings for helicopter and instruments. He holds an unrestricted first-class medical certificate; the certificate was issued on September 1, 1995. Safety Board investigators examined the second pilot's last flight hours logbook. The flight hours reflected in Supplement E of this report were obtained from the examination. According to FAA records, the second pilot received the Airline Transport Pilot certificate on July 27, 1995; a Robinson R-44 helicopter was used for the flight test. This flight test satisfies the BFR requirement of federal air regulations. Aircraft Information Safety Board investigators examined the helicopter's maintenance records. The records examination disclosed that the operator's mechanic did the last 100-hour inspection on March 20, 1996. At the time of the accident, the helicopter accrued 3,540 hours. According to the hobbsmeter log, a renter pilot reported that the engine sustained a momentary loss of engine power on April 24, 1996. The maintenance records revealed that a company mechanic replaced the seals in both magnetos. Wreckage and Impact Information Safety Board investigators examined the wreckage at John Wayne Airport, Martin Aviation, on May 1, 1996. For security purposes, the operator removed the aft section of the tail boom assembly and the instrument panel before retrieving the wreckage from the accident site. Safety Board investigators established continuity of the rotating group, except the tail rotor system, by operating their respective control mechanisms. The cyclic and collective control tubes from the cockpit through the "broom closet" to the rotor mast assembly were intact and connected at their respective attach points. The swash plate and swash plate sub assembly were found intact. A lever arm that the pitch change links connect to the main rotor blades was broken. The associated pitch change link connecting bolt, nut, and washer, were intact; however, the pitch change link was bent. The remaining pitch change link was found connected to the swash plate lever arm and its associated main rotor blade. Continuity of the rotor mast assembly to the transmission output drive shaft was established. Both main rotor blades remained attached to the hub assembly and did not display any S twisting signatures. One rotor blade was partially pulled away from the hub assembly. Main rotor blade, serial number 7863A, displayed compression buckling and was bowed upward. The underside of the blade displayed 45-degree tangential to the blade chord scrape marks. The blade's leading edge did not exhibit any leading edge gouging. The remaining main rotor blade, serial number 7855A, displayed trailing edge impact damage at its outboard end. There were no ground scrape marks or bowing signatures observed. The tail rotor output drive shaft remained connected to the transmission through the clutch assembly. The attaching yokes (a.k.a. Thomas couplings) were intact. The tail rotor drive shaft fractured about 24 inches forward of the vertical fin. The drive shaft fracture displayed several circular zinc chromated colored score marks next to the tail boom bulkhead and torsional overload characteristics. The connecting tail rotor pedal tube also fractured at the tail rotor drive shaft area. The fracture surface displayed a main rotor blade impact signature. The tail rotor assembly remained connected the tail rotor 90-degree gear box. Both tail rotor blades did not display any impact signatures. The horizontal stabilizer was found buckled; the vertical stabilizer was not damaged. The engine was examined at Lynn's Aircraft Engines, Inc., El Monte, California, on May 2, 1996. The parties listed in this report participated in the examination. The engine did not exhibit any external damage. Additional Information The main wreckage, except for the engine assembly, was verbally released to the operator on May 1, 1996. The main wreckage was at Martin Aviation when it was released. The engine was released to the operator on May 2, 1996; the engine was located at Lynn's Aircraft Engines when it was released.
the pilot misjudged the helicopter's distance and altitude and failed to attain the proper descent rate.
Source: NTSB Aviation Accident Database
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