Aerospatiale AS350BA accident near Princeville, Hawaii, March 9, 2007
On March 9, 2007 at about 1:02 am local time, a Aerospatiale AS350BA (helicopter), registered N354NT, was substantially damaged in an accident near Princeville, Hawaii (Princeville airport). It was flown under charter and air-taxi rules (Part 135). 4 people were killed and 3 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of maintenance personnel to properly tighten (torque) the flight control servo lower attachment clevis, and reinstall a functioning lock washer, which resulted in a flight control disconnect and a complete loss of helicopter control. Contributing to the accident was the operator's failure to ensure its maintenance program was being executed in accordance with Federal regulations.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 9, 2007 · about 1:02 am local time
- Place
- Princeville, Hawaii · Princeville · map
- Type
- Accident
- Injuries
- 4 people were killed and 3 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale AS350BA · all AS350BAs on the register
- Registration
- N354NT · no longer on the register · serial 1168
- Damage
- Substantial damage
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
The helicopter was returning from a sightseeing flight when the pilot contacted the dispatcher and announced, "I'm having hydraulic problems, and I'm probably going to have to do a run-on landing." The language he used to describe his situation changed from "hydraulic problem" to "hydraulic failure" as the flight proceeded. The pilot did not immediately land at the approach end of the runway; instead, he continued to the departure end, where the passenger terminal was located. The helicopter approached the mid-point of the runway, and as it neared the surface, the dispatcher heard the pilot state, "Okay we're done." Then, the sound of the rotor changed pitch and the helicopter impacted the ground. Postaccident examination of the helicopter revealed that the left lateral flight control servo became disconnected in flight at the transmission. Further examination revealed that the lower clevis of the left lateral servo was still attached to the transmission case, but was no longer attached to the servo. The threads on the clevis, as well as the threads on the inner diameter of the servo, appeared undamaged. The jam nut, lock nut washer, and safety wire were still attached to the clevis threads and rotated freely. The lock washer was severely worn and the locking tang was missing. Metallurgical testing and torque testing of the accident servos revealed that the jam nut, washer, and piston rod were able to easily rotate off of the clevis if no torque was applied and with the locking tang missing. Under normal loads, the main hydraulic flight control servos experience slight twisting that could contribute to the servo rotating off the clevis bolt (without an intact and functioning locking washer installed). Therefore, the investigation revealed that the servo attachment nut was not torqued during maintenance about one month prior to the accident, and the lack of torque, coupled with the installation of a severely worn lock washer, allowed the servo to rotate off of the clevis during the accident flight, resulting in a complete disengagement of the servo from its mounting clevis on the transmission. Examination of the company maintenance program revealed that none of the mechanics at the helicopter's base had received factory training, and that the maintenance manuals they used were three revisions out of date. Mandatory quality control inspections of maintenance actions, as well as post-maintenance test flights prescribed in the General Operator's Manual and the manufacturer's maintenance manuals (that included the replacement of the flight control servo), were not performed. (This report was modified on June 16, 2009)
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
Pilot
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: instructor: helicopter; rotorcraft: helicopter
- Flight time: 10,471 hours in all; 3,500 in this make and model
- Last flight review: February 1, 2007
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: rgt
- Injury: fatal
The aircraft
- Airframe total time: 21,706 hours
- Last inspection: 100-hour inspection, February 22, 2007; 64 hours since
- Maximum gross weight: 4,630 lb
- Seats: 7
- Landing gear: fixed
- Engine: Turbomeca Arriel 1B (turboshaft); 0 hours total
- Operator: Heli-Usa Airways, Inc.
The flight
- Departed from: HI01 Princeville HI
- Destination: HI01
- Runway 05, 3,560 ft by 40 ft
Weather at the time
- Light: daylight
- Wind: from 050° at 13 knots
- Visibility: 10 statute miles
- Sky: scat at 5,500 ft
- Temperature: 73°F (23°C), dew point 54°F (12°C)
- Altimeter: 29.90 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 3 | 3 |
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.