Individually Owned: 150,657
Corporate Owned: 137,281
N/A Airport
Aircraft Accident/Incident Report
Aberdeen, South Dakota 57401
Saturday, April 14, 2012 2:55 CDT
NTSB Narrative Summary Released at Completion of Accident
The pilot reported that, shortly after departure, the helicopter yawed left and that he heard a “loud howling/grinding sound” emanating from the upper area of the helicopter. He subsequently reduced power and performed a minimum power descent to an open area. During the landing, the helicopter touched down hard. A postimpact examination of the engine found that two third-stage turbine wheel blades had cracked and separated due to high-cycle fatigue at the trailing edge during operation of one or more natural frequencies of the wheel. Four additional blades displayed fatigue cracks. Metallurgy examinations revealed that the blades had no evidence of material anomalies and met the material hardness and composition specifications. The observed high-cycle fatigue initiation and propagation characteristics were consistent with operating in a condition conducive to vibration. The engine manufacturer plans to release design changes that will increase the operating speed natural frequency margin and improve the vibration margin.
NTSB Probable Cause Narrative
The fatigue failure of two turbine engine blades due to vibration.
Event Information
| Type of Event | Accident |
| Event Date | 4/14/2012 |
| Event Day of the Week | Saturday |
| Time of Event | 255 |
| Event Time Zone | Central Daylight Time |
| Event City | Aberdeen |
| Event State | SOUTH DAKOTA |
| Event Country | -- |
| Zipcode of the event site | 57401 |
| Event Date Year | 2012 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 452800N |
| Event Location Longitude | 0982835W |
| Event Location Airport | N/A |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 253 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 118 |
| Weather Observation Facility ID | KABR |
| Elevation of weather observation facility | 1302 |
| Distance of event from weather observation facility (units?) | 2 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Night |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 5 |
| Air Temperature at event time (in degrees celsius) | 3 |
| Dew Point at event time (in degress fahrenheit) | 2 |
| Wind Direction (degrees magnetic) | 240 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 3 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.7 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | METAR KABR 140753Z AUTO 24003KT 5SM BR CLR 03/02 A |
| Event Highest Injury | Minor |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | 1 |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 32011 |
| NTSB Notification Source | Med-Trans Corportation |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Apr 15 2014 10:59AM |
| User who most recently changed record | aguj |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N509MT |
| NTSB Number | CEN12LA242 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BELL |
| Aircraft Model | 407 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 53281 |
| Certified Max Gross Weight | 5250 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 1 |
| Cabin Crew Seats | 3 |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 4 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | AAIP |
| Date of Last Inspection | Mar 26 2012 12:00AM |
| Airframe hours since last inspection | 36 |
| Airframe Hours | 7379 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | C126 |
| Aircraft Owner Name | MED-TRANS CORP |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | TUCSON |
| Aircraft Owner State | AZ |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 85714-3409 |
| Operator is an individual? | No |
| Operator Name | MED-TRANS CORP |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | TUCSON |
| Operator State | AZ |
| Operator Country | USA |
| Operator Zip code | 85714-3409 |
| Operator Code | -- |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Non-scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Positioning |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | KABR |
| Departure City | Aberdeen |
| Departure State | SD |
| Departure Country | USA |
| Departure Time | 250 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | SD54 |
| Destination City | Aberdeen |
| Destination State | SD |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Nov 26 2013 12:56PM |
| User who most recently changed record | broda |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | Yes |
| Medical Flight | -- |