# NTSB DEN99LA040: Hughes 369D, Baggs, WY, February 16, 1999 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: February 15, 1999, 17:15 local (Feb 16, 1999, 00:15 UTC) - Place: Baggs, WY - Coordinates: 41.029842, -107.65081 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=41.0298&lon=-107.6508&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report May 8, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 45762 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA040 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45762/pdf - Page: https://openairdocs.org/ntsb/DEN99LA040 ## Probable cause A hard landing resulting from rotor rpm decay. Factors were the improper replacement of the turbine by company maintenance personnel resulting in the PC line nut becoming loose, and the pilot operating outside the normal height/velocity curve. ## Analysis The helicopter was conducting a seismic survey operation at 200 to 250 feet agl at 40 knots when the engine's automatic re-ignition system caution light illuminated, followed by an immediate loss of main rotor rpm. The pilot unsuccessfully attempted to perform an autorotation, and the aircraft impacted the ground. A postaccident examination of the turboshaft engine was performed, revealing that the PC line 'B' nut between the fuel control unit (FCU) and the power turbine governor (PTG) was not connected at the FCU, resulting in a loss of engine pneumatic pressure. According to aircraft maintenance records, the turbine section of the engine was removed by company maintenance and replaced with a rental turbine. The PC line and various pneumatic and fuel system lines had been removed to facilitate removal and replacement of the engine's turbine section. The helicopter had flown 6.1 hours since the turbine was replaced. ## Factual narrative On February 15, 1999, approximately 1715 mountain standard time, a Hughes 369D, C-GDCM, operated by Peace Helicopters of Edmonton, Alberta, Canada, was substantially damaged after impacting terrain following a loss of engine power while maneuvering nears Baggs, Wyoming. The Canadian registered commercial pilot, the sole occupant aboard, was seriously injured. The aircraft was being operated under Title 14 CFR Part 91, and a company VFR flight plan was filed. The flight originated from a local staging area approximately 10 minutes before the accident. Visual meteorological conditions prevailed. According to the pilot, the flight was being conducted as a seismic survey operation, and he was repositioning supplies for ground team members with a long line hook up. While flying at 200 to 250 feet above the ground (agl) at approximately 40 knots airspeed, the pilot observed that the engine's automatic re-ignition system caution light had illuminated, followed by an immediate loss of main rotor rpm. The helicopter yawed to the left, followed by a sudden turbine deceleration. The pilot stated that he attempted to perform an autorotation, but was unsuccessful due to the helicopter's low altitude and airspeed. The aircraft impacted the ground, causing structural distortion to the underside of the fuselage due to landing gear overload fractures, and damaging the upper fuselage due to the downward flexing of the tail boom. The elapsed time between first engine warning and impact with the ground was approximately 4 to 5 seconds. A postaccident examination of the turboshaft engine was performed by the FAA, with the assistance of engineering representatives from Rolls-Royce Allison and the Boeing Company. The inspection revealed that the PC line "B" nut between the fuel control unit (FCU) and the power turbine governor (PTG) was not connected at the FCU. The nut had completely backed off the threads of the fitting, resulting in a loss of engine pneumatic pressure. All additional oil and fuel lines were intact. During the investigation, air at 40 psi was supplied to the system, revealing the PC line leak. When the PC line fitting was connected and torqued, air was again supplied to the system. No additional leaks were observed. According to aircraft maintenance records supplied by the operator, the turbine section of the engine was removed by company maintenance personnel on February 12, 1999, and replaced with a rental turbine. The PC line and various pneumatic and fuel system lines had been removed to facilitate removal and replacement of the engine's turbine section. The helicopter had flown 6.1 flight hours since the installation which occurred 3 days prior to the accident. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, maneuvering - turbine assembly (contributing factor) - maintenance,replacement - improper, company maintenance personnel (contributing factor) - fuel system,pc line - loose part/bolt/nut/clamp/etc (contributing factor) - Hard landing, descent - emergency - autorotation - attempted, pilot in command - height/velocity curve, pilot in command (contributing factor) - rotor rpm - not maintained, pilot in command (cause) - terrain condition - open field ## Aircraft - Registration: CGDCM (not matched to a registry record) - Reported make and model: Hughes 369D - Category: Helicopter - Serial number: 310916D - Airframe hours: 10762 - Engines: Allison 250-C20B 425 horsepower turbo shaft - Damage: Substantial damage - Flight: Other work use, Part 91 - Registered owner: Peace Helicopters Ltd. - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, January 16, 1999, 71 hours before - Departed: NONE, WY - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 31; commercial; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 2,298 total, 51 in this make and model, 2,100 as pilot in command, 128 in the last 90 days, 41 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 15 knots - Visibility: 40 statute miles - Lowest ceiling: 2,500 ft broken - Temperature: 32 °F, dew point 19 °F - Altimeter: 30.00 inHg - Observed at: RWL, 45 nm away From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.