# NTSB CHI07IA042: Bell 407, N302LE, Raytown, MO, December 12, 2006 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: December 11, 2006, 22:17 local (Dec 12, 2006, 04:17 UTC) - Place: Raytown, MO - Coordinates: 39.049297, -94.490234 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.0493&lon=-94.4902&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 4 uninjured - Status: Completed, report March 31, 2008 - Report: Approved by Office Director - Parties: Standard Aero, Rolls Royce, Life Flight Eagle, Federal Aviation Administration, CJ Systems Aviation Group, Bell Helicopter - NTSB case key (mKey): 65062 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI07IA042 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/65062/pdf - Page: https://openairdocs.org/ntsb/CHI07IA042 ## Probable cause The loss of engine power during cruise flight due to third stage turbine wheel blade fatigue and subsequent separation, which resulted in an emergency landing. ## 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, cruise - turbine assembly,turbine blade - fatigue (cause) - turbine assembly,turbine blade - separation (cause) - Forced landing, emergency descent/landing ## Analysis The air ambulance helicopter executed an emergency landing on an elementary school parking lot following a loss of engine power. Night visual meteorological conditions prevailed at the time of the incident. The pilot stated that he heard a bang and got a low frequency vibration during cruise flight. The helicopter received minor damage due to internal engine components exiting the engine collector and exhaust stack. Examination of the third stage turbine wheel noted high cycle fatigue features on the fracture surface of one of the blades. The fatigue initiated at the trailing edge of the airfoil and propagated 0.515 inch before a fast fracture separation. Although a small area of porosity was observed in the microstructure adjacent to the fracture, it did not intersect the fracture surface, and no evidence of porosity was observed on the fracture surface. Chemistry and hardness were as specified. Given the high cycle features, good material properties, and lack of a stress-concentrating defect at the origin, the fatigue could be secondary to some other event that produced unusual loading or vibrations in the blade. ## Factual narrative On December 11, 2006, at 2217 central standard time, a Bell 407, N302LE, operated by CJ Systems Aviation Group (dba Life Flight Eagle), as an air ambulance helicopter, executed an emergency landing on an elementary school parking lot near Raytown, Missouri. Night visual meteorological conditions prevailed at the time of the incident. The pilot stated that he heard a bang and got a low frequency vibration during cruise flight. The helicopter received minor damage due to internal engine components exiting the engine collector and exhaust stack. The air ambulance flight was operating under Title 14 CFR Part 135. The pilot, two paramedics, and patient were uninjured. The flight last departed from Golden Valley Hospital, Clinton, Missouri, at 2154, for a patient transfer to St. Lukes Hospital, Kansas City, Missouri. The National Transportation Safety Board Materials Lab review of the Rolls Royce Metallurgical Investigation Report focused on damage to the third stage turbine wheel where high cycle fatigue features were observed on the fracture surface of one of the blades. The fatigue initiated at the trailing edge of the airfoil and propagated 0.515 inch before a fast fracture separation. Although a small area of porosity was observed in the microstructure adjacent to the fracture, it did not intersect the fracture surface, and no evidence of porosity was observed on the fracture surface. Chemistry and hardness were as specified. Parties to the investigation were Bell Helicopter, CJ Systems Aviation Group, FAA, Life Flight Eagle, Standard Aero, and Rolls Royce. ## Aircraft - Registration: N302LE (not matched to a registry record) - Reported make and model: Bell 407 - Category: Helicopter - Serial number: 53572 - Airframe hours: 1865 - Engines: Rolls-Royce Turbomeca 250-C47B 630 horsepower turbo shaft - Damage: Minor damage - Flight: Part 135 - Operator: CJ Systems Aviation Group, Inc. - Registered owner: Lifeflight Eagle Inc - Airworthiness certificate: Standard, Normal - Departed: Clinton, MO - Destination: Kansas City, MO - Flight plan: Company VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 52; injuries: none; private, commercial; airplane ratings: single-engine land; instrument ratings: helicopter; medical: class 2, with waivers/limitations; last flight review December 1, 2006; seat: right; flight hours: 6,525 total, 100 in this make and model, 6,225 as pilot in command ## Weather - Conditions: Visual (VMC), Night/bright - Wind: 180° at 13 knots, gusting 20 - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 55 °F, dew point 48 °F - Altimeter: 29.90 inHg - Observed at: MKC ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20061211026119I](https://openairdocs.org/incident/20061211026119I), Dec 11, 2006: Bell 407, Raytown, MO, Minor damage. (-23) On December 11, 2006, at 2217 CST, a Bell 407, N302LE, operated by cj systems aviation group (dba life flight eagle) as an air ambulance, executed an… 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.