Mcdonnell Douglas Helicopter 369E accident near Acworth, Georgia, August 12, 2009
On August 12, 2009 at about 2:00 pm local time, a Mcdonnell Douglas Helicopter 369E, registered N527BB, was substantially damaged in an accident during enroute (descent) near Acworth, Georgia. It was an aerial observation flight under general aviation rules (Part 91). 1 person was seriously injured and 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The loss of engine power due to the fatigue failure of the third-stage turbine wheel airfoil.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 12, 2009 · about 2:00 pm local time
- Place
- Acworth, Georgia · map
- Type
- Accident
- Injuries
- 1 person was seriously injured and 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Mcdonnell Douglas Helicopter 369E · all 369Es on the register
- Registration
- N527BB · no longer on the register · serial 0329E
- Damage
- Substantial damage
- Flight
- Aerial observation flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot stated that he and an observer were conducting an aerial observation when during the descent he heard a loud noise. Subsequently, he received an "ENG OUT" audio and caution lights, and made an emergency autorotation into a field. An examination of the engine’s turbine section revealed rub marks throughout the turbine section consistent with an out-of-balance condition caused by a third-stage turbine airfoil release. The third-stage wheel airfoil fractured in fatigue near the root of the airfoil and no anomalies were found at the fatigue origin. The fracture surface of the failed third-stage blade revealed high-cycle fatigue failure over an extended period of time. The crack propagation is estimated to be greater than 2000 cycles. No additional cracks were found on the other third-stage wheel airfoils. Review of the logbook revealed that the airframe engine total time was 3,820 hours and the engine had gone through a 100- and 300-hour inspection at 3,809.6 engine hours. All airworthiness directives and applicable service bulletins as well as all instructions for continued airworthiness were complied with. The hot section and turbine inspection was completed on February 21, 2008, at 2,958 hours. The third-stage turbine wheel was overhauled on February 3, 2004, at 1210.6 hours and 1633.0 cycles and was due to be replaced at 4,710.6 hours. At the time of the accident the wheel had 2609.7 hours and 2412.0 cycles.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (total) during enroute (descent) defining event
- Off-field or emergency landing during emergency descent
- Autorotation Collision with terrain or object (not controlled flight into terrain)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Turbine section › Failure
Crew member
- Certificate: commercial pilot
- Ratings: instrument: helicopter; rotorcraft: helicopter
- Flight time: 1,038 hours in all; 95 in this make and model; 33 in the last 90 days; 33 in the last 30 days; 563 as pilot in command
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 4,257 hours
- Last inspection: 100-hour inspection, August 1, 2009; 10 hours since
- Maximum gross weight: 3,100 lb
- Seats: 4
- Landing gear: fixed
- Engine: Allison 250-C20 SER (turboshaft); 0 hours total
- Operator: Rotorworks LLC
The flight
- Departed from: RYY Acworth GA at 1:00 pm
- Destination: RYY Acworth GA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 330° at 5 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 11,000 ft; scat at 4,000 ft
- Temperature: 81°F (27°C), dew point 70°F (21°C)
- Altimeter: 30.03 inHg
- Observation at 12:47 pm from RYY, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.