History of Flight
On January 4, 2009, at 1409 Central Standard Time, a Sikorsky S-76C++ helicopter, registration N748P, operated by PHI, Inc., as a 14 CFR Part 135 air taxi flight under day visual flight rules, crashed into marshy terrain approximately 7 minutes after takeoff and 12 miles southeast of the departure heliport. The helicopter sustained substantial damage. Both pilots and six of the seven passengers were killed; one passenger was critically injured. The helicopter departed Lake Palourde Base Heliport (7LS3) in Amelia, Louisiana, en route to the South Timbalier oil platform ST301B. No flight plan was filed with the FAA; a company flight following plan was filed with the PHI Communications Center. The flight was tracked via Outerlink, a satellite-based system. The helicopter's flight track ended at 1409. A search operation began at 1414 after a 406 MHz ELT distress signal was received. The wreckage was found partially submerged in a marshy bayou.
Data from the cockpit voice recorder and flight data recorder indicated the helicopter was in level cruise at 850 feet mean sea level at 135 knots indicated airspeed when a loud bang occurred, followed by rushing wind sounds, engine power reductions, and main rotor rpm decay. The recording ended 17 seconds later.
Aircraft Information
The twin-engine, 14-seat, 2-year-old helicopter was equipped with glass cockpit instrumentation, a combined CVR/FDR, EGPWS, and other recorders. The engines were Turbomeca Arriel 2S2 with digital engine control units. The helicopter had replacement windshields installed in 2007 under Supplemental Type Certificate SR01340AT; these were replaced again in 2008 due to cracking. The low rotor speed warning system was visual only via the integrated instrument display system (IIDS), with no audible alarm or master warning light.
Personnel Information
The 63-year-old captain had approximately 15,373 flight hours, including 5,423 in the S-76. The 46-year-old co-pilot had about 5,524 flight hours, with 962 in the S-76. Both pilots held appropriate certificates and medical certificates with corrective lens restrictions. Their training records indicated completion of required training.
Meteorological Information
Weather at Amelia at 1430 CST reported scattered clouds at 1,500 and 3,500 feet, broken at 10,000 feet, visibility 10 miles, wind from 160 degrees at 6 knots, temperature 24°C, dew point 19°C.
Wreckage and Impact Information
The helicopter impacted on its left side on an approximate heading of 120 degrees, with extensive deformation. The tail boom separated; main rotor blades showed low-speed rotation damage. Engines exhibited impact deformation but no pre-impact anomalies. Control continuity could not be fully established due to crush deformation. No evidence of fire, fuel leaks, or oil leaks was found.
Flight Recorder Information
The CVR recorded a bang and loud air noise, followed by decreasing rotor and engine rpm. The FDR data were consistent. Engine EECU non-volatile memory showed no faults.
Tests and Research
Examination of the engines revealed no anomalies other than impact damage. The No. 2 engine's hydromechanical unit (HMU) was tested and functioned normally; the No. 1 HMU was impact-damaged and not tested. Resolver positions indicated fuel flow levels. Flight computer testing showed only routine error codes. Bird strike analysis: swabs from the windscreen and other areas contained microscopic remains of a female red-tailed hawk, average weight 2.4 pounds. Evidence of bird remains was also found under a windscreen seal and in an engine air filter. Main rotor servo actuators were CT-scanned and functionally tested; most results were within tolerances except for a few test points (lateral servo interstage position error and input force level; forward servo system 1 low side pressure switch). Disassembly found no internal damage or contamination. No pre-impact anomalies were identified in any aircraft systems associated with the accident sequence.