Agustawestland Philadelphia AW139 accident near Galliano, Louisiana, April 7, 2016
On April 7, 2016, a 2013 Agustawestland Philadelphia AW139 (helicopter), registered N639NA, was substantially damaged in an accident during enroute near Galliano, Louisiana (South Lafourche Leonard Miller airport). It was an other work-use flight under general aviation rules (Part 91). No one was hurt; 9 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fatigue failure of a tail rotor blade erosion shield extension, which resulted in in-flight damage to a main rotor blade.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 7, 2016
- Place
- Galliano, Louisiana · South Lafourche Leonard Miller · map
- Type
- Accident
- Injuries
- No one was hurt; 9 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Agustawestland Philadelphia AW139, built 2013 · all AW139s on the register
- Registration
- N639NA · registry record · serial 41326
- Damage
- Substantial damage
- Flight
- Other work-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During a business flight over the Gulf of Mexico, the crew felt a slight vibration of the tail rotor with no other anomalies noted and landed the helicopter uneventfully at their planned destination. A postflight inspection revealed that one of the tail rotor blade erosion shield extensions, also known as a lightning strip (LS), was missing and that only its side tabs remained attached to the blade. One of the main rotor blade tips sustained substantial damage when the LS separated from the tail rotor blade and impacted the bottom of the main rotor blade. Metallurgical analysis of the fractured LS revealed microcavities in the metal, which resulted in a fatigue fracture. The helicopter manufacturer concluded that the microcavities were a direct result of the electroplating manufacturing process. Finite element modeling (FEM) of an exemplar LS revealed that the maximum stress values expected during flight were considerably lower than the fatigue limit specified for the electroplated nickel material. The microcavity observed on the accident LS could not be replicated by the FEM model, but the presence of a microcavity could adversely influence the in-flight stresses and reduce the overall strength of the LS. Additional flight testing with strain gauges did not reveal any load condition that would lead to similar LS failures that were experienced during the accident flight. It is likely the LS separated in flight due to a fatigue fracture that was the result of increased stress in the presence of a material flaw that had existed since its manufacture. The helicopter manufacturer, in response to multiple reports of similar LS failures, changed the material specification from electroplated nickel to a higher strength steel. The steel LS will be installed on all newly built helicopters, and an optional service bulletin will be issued to operators to provide the steel LS upon request.
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
- Part(s) separation from AC during enroute defining event
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Tail rotor › (general) › Fatigue/wear/corrosion
- Organizational issues › Development › Manufacture/production › Equipment manufacture › Manufacturer
Pilot
- Certificate: airline transport pilot
- Ratings: instructor: helicopter; instrument: helicopter; rotorcraft: helicopter
- Flight time: 14,500 hours in all; 1,250 in this make and model; 125 in the last 90 days; 35 in the last 30 days; 12,000 as pilot in command
- Last flight review: October 31, 2015
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot
- Ratings: single-engine land; instructor: helicopter; instructor: instrument helicopter; rotorcraft: helicopter
- Flight time: 5,792 hours in all; 1,813 in this make and model; 114 in the last 90 days; 32 in the last 30 days; 2,866 as pilot in command
- Last flight review: October 31, 2015
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 2,497.8 hours
- Last inspection: continuous airworthiness programme, April 6, 2016
- Maximum gross weight: 14,991 lb
- Seats: 14
- Landing gear: fixed
- Engine 1: P&W Canada PT6C-67C (turboshaft); 6,970 hours total
- Engine 2: P&W Canada PT6C-67C (turboshaft); 2,498 hours total
- Operator: Chevron USA INC
The flight
- Departed from: GAO Galliano LA at 11:00 am
- Destination: GAO Galliano LA
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 340° at 7 knots
- Visibility: 10 statute miles
- Temperature: 72°F (22°C), dew point 54°F (12°C)
- Altimeter: 30.03 inHg
- Observation at 2:15 pm from KXPY, 19 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 | |||
| Passengers | 7 |
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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CEN16LA401.