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 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 was filed.
All three pilots stated that prior to departure, weather at WJF was chosen due to clear conditions. En route, ATIS indicated visibility more than 6 statute miles, clear skies, wind 12 knots gusting to 19 knots. They also discussed the “4H’s – High, Hot, Heavy, and Humid.” Upon arrival, the altimeter was set to field elevation. The intent was to initiate maneuvers at 500 feet above ground level. Several maneuvers were performed with no issues. The flight continued with two 180-degree autorotations. On the first, the CFI noted the helicopter was not going to make the intended landing spot and was steeper than normal; he reapplied power to go around. On the second, the maneuver was initiated at 500 feet agl. According to the CFI, while on downwind he cut the power, the flying pilot turned 90 degrees, then the helicopter developed a high sink rate and was pushed away from the spot. The CFI reapplied power, but the engine did not come back online. The flying pilot returned the helicopter to straight and level before it struck the dirt.
Training
According to the LAPD instructor’s guide, a power recovery is used to terminate practice autorotations. Under Non-Standard Autorotations, a 180-degree autorotation requires an entry altitude of 700 feet agl or higher for practice. Normal training locations are Los Alamitos Army Airfield and Point Mugu Naval Air Station, both with dedicated ARFF crews. WJF does not have dedicated ARFF crews. Per LAPD, patrol altitude can be 500-800 feet.
The helicopter’s AFM includes a training procedure for autorotations, allowing full autorotation with simulated engine flame-out. The procedure: lower collective to enter autorotation, maintain NR in green, reduce power maintaining Ng above 67%, apply autorotation procedure except for engine/fuel shut-off/fuel select, after landing bring fuel flow control lever to flight detent. Notes state it must be conducted within gliding distance to a suitable landing site, and steps to lower collective and maintain NR precede power reduction.
Personnel Information
Right-seat pilot (flying pilot): 54 years old, held commercial pilot certificate with rotorcraft-helicopter rating and private pilot airplane single-engine land. Second-class medical certificate issued July 17, 2009, with limitation for glasses for distant vision. Total time 9,200 hours, 5,700 in make/model; 90 hours in last 90 days, 30 in last 30.
Left-seat pilot (CFI): 50 years old, held commercial pilot certificate with ratings for airplane single/multi-engine land, rotorcraft-helicopter, instrument airplane/helicopter. Second-class medical certificate issued February 25, 2009, no limitations. Total time 2,764 hours, 1,073 in make/model; 112 hours in last 90 days, 27 in last 30.
Aircraft Information
A 100/200-hour inspection was completed July 30, 2009, total time 11,198.2 hours. On August 1, 2009, a 100/200-hour Starflex inspection was completed. The helicopter was flown 8 days including the accident for about 52 hours. An annual inspection was completed June 2, 2009, at 10,995.8 hours.
The engine, Turbomeca Arriel 1D1 S/N 19030, was originally installed on N661PD, another LAPD helicopter. On July 12, 2006, it was removed and installed on N217LA with a new fuel control unit. In the preceding 90 days, a 100/200-hour inspection was done July 30, 2009. Engine total time: 4,317.1 hours.
Meteorological Information
WJF special weather observation at 1237: wind 240 degrees at 13 knots gusting to 18 knots; visibility 25 statute miles; scattered clouds at 7,000 feet; temperature 35°C; dew point -1°C; altimeter 29.97 inHg. Density altitude 5,214 feet. Airport elevation 2,351 feet.
Wreckage and Impact Information
The accident site was at the south end of the airport. Helicopter came to rest upright on heading 250 degrees in a dirt area adjacent to taxiway A. First point of impact was about 35 feet left and behind. Left skid detached at forward/aft cross tubes; right skid separated but remained underneath. Fuselage skin and Plexiglas were in debris path.
Main rotor blades remained attached. Red blade exhibited trailing edge separation and chordwise scratching 3 inches inboard from tip. Yellow and blue blades had downward coning; yellow had trailing edge separation and scratch marks; blue had minor scratch marks. Tail rotor assembly remained attached; blades exhibited leading/trailing edge damage, delamination, torsional twisting; one tip broken and mostly separated.
Tests and Research
On August 27-28, 2009, NTSB, LAPD, American Eurocopter, and Turbomeca USA examined the airframe and engine. Detailed inspection notes are in the public docket.
Airframe: Cabin area had impact damage consistent with high vertical rate of descent. Both front seats laterally fractured below seat pan; left rear seat deformed downward. Dual flight controls: collectives between mid- and high pitch; cyclic sticks forward and slightly right; anti-torque pedals near neutral. Flight control continuity established. Fuel flow control lever OFF; fuel cutoff lever aft. Continuity confirmed.
Transmission manually rotated with no binding. Starflex yellow arm had 45-degree fracture consistent with powered main rotor blade impact. Impact marks between blade bolts and hub consistent with excessive blade flapping. Main rotor blades showed impact damage and rotational scoring near tips, attributed to ground impact. Trailing edge splitting consistent with lower than nominal rotor rpm at impact.
Fuselage to tail boom junction had compression signatures on lower side. Left horizontal stabilizer had impact mark near tip; manufacturer indicated direction and dimension consistent with main rotor blade strike. Right lower vertical fin and tail cone had compression signatures and torsional damage. Skids separated at ankles; cross tubes rolled aft, allowing belly contact.
Tail rotor damage consistent with ground impact; both strike tabs bent inward. Tail rotor drive shaft showed rotational scoring forward to aft spline coupling; coupling had rotational scoring. Hanger bearings rotated freely. Fuel tank and system compromised; fuel filter no debris. Caution warning panel no filament stretch. Vertical acceleration approximately 12 g’s.
Engine: Remained attached; no fluid leaks; oil level within limits. Hoses, pipes, harnesses intact. Modules examined: MO1 no anomalies; chip detectors/magnetic plug clear; starter/generator splines no deformation; fuel filter bypass not popped; fuel control lever moved accordingly. MO2 axial rotor rotated with no unusual noises; axial blades no rub; bleed valve open; nozzle guide vanes undamaged. MO3 gas generator turbine casing no damage; borescope of first stage blades no damage. MO4 containment ring not damaged; free turbine moved freely; blades undamaged; exhaust pipe unremarkable. MO5 reduction gearbox casing unremarkable; magnetic plug free of debris.
On October 27-29, 2009, further engine examination at Turbomeca USA in Grand Prairie, Texas. Dent on linking tube. Grinding noise when axial wheel manually rotated; front stage turbine wheel rotated with no unusual noise; borescope no anomalies. Engine run in test cell for 1 hour 22 minutes; with exception of bleed valve opening slightly above threshold, operated within specifications.
Additional Information
The helicopter was equipped with an AeroComputers UltiChart LE-5000 digital mapping system (S/N 2247) capable of recording heading, speed, altitude, date/time, location. Initial download showed first autorotation started at 350 feet; second at 300 feet with airspeed slower than 60 knots. Unit had not been updated and compact flash corrupted. AeroComputers successfully downloaded video (in public docket). Recovered data showed average descent of 1,747 feet per minute over 8 seconds.
The passenger opined that extra weight of a third person on one side may have made recovery more difficult in an emergency, and suggested only necessary persons be aboard during non-standard flights. He also indicated improved rear seat safety features could have lessened his injuries.