WPR09GA397

The pilots’ decision to conduct a practice autorotation at low altitude in high density altitude conditions and their failure to attain and maintain an appropriate descent rate. Contributing to the accident was the high density altitude and the pilots’ failure to comply with Los Angeles Police Department guidance.

Due to inclement weather at their normal training airports, the commercial pilot and flight instructor chose to practice maneuvers for an upcoming proficiency flight at an airport in the high desert that had clear weather conditions. While en route to that airport, the pilots discussed the “4H’s - High, Heavy, Hot, and Humid” and their effects on performance. The pilots intended to initiate all maneuvers about 500 feet above ground level (agl). This was contrary to the Los Angeles Police Department instructor's guide, which specifies that such maneuvers be initiated 700 feet agl. After performing several training maneuvers with no incident, the pilots performed two autorotations. During the first autorotation, the approach became unstabilized, and the flight instructor initiated a power recovery. The flight instructor reported that during the second autorotation, the helicopter developed a high sink rate and was pushed away from the intended landing spot by the wind. The flight instructor said that he again initiated a power recovery, but the engine did not seem to be producing the necessary power, and the helicopter landed hard. Postaccident examination revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Downloaded data from a recording device on the helicopter revealed that the accident autorotation was initiated about 300 feet agl and resulted in an average descent rate of 1,747 feet per minute during the 8 seconds before the helicopter struck the ground. The calculated density altitude at the time of the accident was 5,214 feet; this condition would have made the engine less responsive, which would have increased the rate of descent. If the maneuver had been initiated at the company-approved altitude of 700 feet, the pilot might have had sufficient altitude to recover from the maneuver in the existing conditions.

HISTORY OF FLIGHT On August 13, 2009, at 1230 Pacific daylight time, a Eurocopter AS 350 B2, N217LA, landed hard following a practice 180-degree autorotation at William J. Fox Field (WJF), Lancaster, California. The Los Angeles Police Department (LAPD) – Air Support Division (ASD), operated the helicopter under the provisions of 14 Code of Federal Regulations Part 91, as a public-use proficiency flight. A certified flight instructor (CFI)/check pilot and two certificated commercial pilots were all seriously injured. The helicopter was substantially damaged. The flight departed Van Nuys Airport (VNY), Van Nuys, California, at 1130. No flight plan had been filed. All three pilots stated that prior to departure from VNY, the weather in the area was reviewed and WJF was chosen due to the clear conditions. Training is normally done at the airports in Los Alamitos and Point Mugu, California. En route to WJF they obtained ATIS information, which indicated visibility more than 6 statute miles, clear skies, wind at 12 knots gusting to 19 knots. They also discussed the “4H’s – High, Hot, Heavy, and Humid, and how they affected flight.” Upon arrival at WJF, the altimeter was set to the field elevation, and the intent was to initiate all maneuvers at 500 feet above ground level. All three pilots reported that several maneuvers were performed with no issues identified. The flight continued with two 180-degree autorotations. The CFI reported that while performing the first 180-degree autorotation, the helicopter was not going to make the intended landing spot, it was steeper than normal; he advised the flying pilot that he was going to reapply power to execute a go-around. On the second 180-degree autorotation, the accident, the pilots stated that the maneuver was initiated at 500 feet agl. According to the CFI, while on downwind he cut the power and the flying pilot turned the helicopter onto the first 90 degrees with no issues. The helicopter developed a high sink rate and was pushed away from its intended landing spot. The CFI reapplied power, and stated that the engine did not come back online. The flying pilot remained on the controls and returned the helicopter to a straight and level attitude before it struck the dirt. TRAINING According to the LAPD instructor’s guide to helicopter flight maneuvers, under the section Autorotations Instructional Techniques, a power recovery is used to terminate practice autorotations. Following a power recovery, a landing can be made or a go-around initiated. Under the section titled Non-Standard Autorotations, an autorotation with a turn (180-degree autorotation) requires an entry altitude of 700 feet agl or higher for practice. Normal training locations are Los Alamitos Army Airfield (SLI), Los Alamitos, and Point Mugu Naval Air Station (Naval Base Ventura County; NTD), Point Mugu. Both airports have dedicated Aircraft Rescue and Fire Fighting (ARFF) crews and equipment. William J. Fox Field Airport does not have dedicated ARFF crews and equipment. According to LAPD personnel, patrol altitude can be between 500-800 feet. The helicopter’s aircraft flight manual (AFM) includes a training procedure for autorotations. This procedure allows for full autorotation with a simulated engine flame-out or loss as opposed to a power recovery. The AFM training procedure is as follows: -Lower collective to enter autorotation. -Maintain NR within the green range of the NR indicator. -Reduce power maintaining the Ng above 67%. -Apply autorotation procedure SECTION 3.1. paragraph 2.1, page 1 of the present Flight Manual except for the engine, fuel shut-off cock and electrical items. -After landing, with the collective at full low pitch, bring the fuel flow control lever to the “flight detent”. -Rotor speed accelerates to its normal governed value. The procedure further notes that autorotation training shall be conducted within gliding distance to a landing site suitable for a running landing. Furthermore, it should be noted that the steps to lower the collective and maintain NR within the green range precede the step to reduce power. PERSONNEL INFORMATION Right-seat pilot (flying pilot) A review of Federal Aviation Administration (FAA) airman records revealed that the 54-year-old pilot held a commercial pilot certificate with a rotorcraft-helicopter rating, as well as private pilot privileges for airplane single-engine land. The pilot held a second-class medical certificate issued on July 17, 2009. It had the limitations that the pilot must wear glasses for distant vision, and possess lenses for near vision. In the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot listed his total time as 9,200 hours with 5,700 hours in the accident make and model. He logged 90 hours in the last 90 days, and 30 in the last 30 days. Left-seat pilot (CFI and non-flying pilot) A review of FAA airman records revealed that the 50-year-old pilot held a commercial pilot certificate with ratings for airplane single and multi-engine land, rotorcraft-helicopter, and instrument airplane and helicopter. The pilot held a second-class medical certificate issued on February 25, 2009; it had no limitations. In the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the pilot listed his total time as 2,764 hours with 1,073 hours in the accident make and model. He logged 112 hours in the last 90 days, and 27 in the last 30 days. AIRCRAFT INFORMATION A review of the helicopter logbooks revealed that a 100/200-hour inspection had been completed and the helicopter was returned to service on July 30, 2009. Total time on the helicopter was 11,198.2 hours at the time of the inspection. On August 1, 2009, a 100/200-hour Starflex inspection was completed, followed by an operational check. The helicopter was then flown 8 days, which included the day of the accident for approximately 52 hours. A review of the records indicated that daily checks were performed with no major issues identified. An annual inspection was completed on June 2, 2009, at which time the helicopter had accrued 10,995.8 total flight hours. According to an entry in the engine logbook, a Turbomeca, Arriel 1D1 serial number (S/N) 19030, engine had originally been installed on N661PD, another LAPD helicopter. On July 12, 2006, the engine was removed and installed on the accident helicopter, N217LA, along with a new fuel control unit, part number (P/N) 0164548720. A review of the engine maintenance records revealed that in the preceding 90 days the engine had undergone a 100/200-hour inspection (July 30, 2009). The engine total time was recorded as 4,317.1 hours. METEOROLOGICAL INFORMATION The airport, WJF, issued a special weather observation report at 1237, which indicated the wind was from 240 degrees at 13 knots gusting to 18 knots; visibility 25 statute miles; a scattered cloud condition at 7,000 feet; temperature 35 degrees Celsius; dew point minus 1 degree Celsius; altimeter setting 29.97 inches of mercury. The calculated density altitude was 5,214 feet. According to the Airport/Facility Directory for WJF, the airport elevation is 2,351 feet. WRECKAGE AND IMPACT INFORMATION The accident site was at the south end of the airport. The helicopter came to rest upright on a magnetic heading of 250 degrees in a dirt area adjacent to taxiway A. The area was comprised of hard-packed desert terrain with relatively little vegetation near the helicopter. The first identified point of impact was approximately 35 feet to the left and behind the helicopter. The left skid had detached at the forward and aft cross tubes, and was located in the debris field. The right skid also separated from the cross tube supports, but remained underneath the helicopter. Fuselage skin and Plexiglas were also ident