# NTSB LAX90LA132: Aerospatiale AS350B, N350AP, Saipan (Pacific Ocean), April 1, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 1, 1990
- Place: Saipan (Pacific Ocean)
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report November 9, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 26766
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX90LA132
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/26766/pdf
- Page: https://openairdocs.org/ntsb/LAX90LA132

## Probable cause

THE PARTIAL FAILURE OF A ROTOR SYSTEM COMPONENT FOR UNDETERMINED REASONS.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, cruise - normal
  - rotor system - failure,partial (cause)
  - rotor drive system - undetermined
- Ditching, descent - emergency
  - terrain condition - none suitable
  - emergency procedure - initiated, pilot in command
  - terrain condition - water
  - terrain condition - rough/uneven

## Analysis

THE PILOT AND PAX WERE CRUISING OVER THE PHILIPPINE SEA WHEN THE PILOT FELT AN EXTREME VIBRATION. THE PILOT MADE AN EMERGENCY LANDING IN THE 7-FT SEA. THE PILOT REPORTED THAT PRIOR TO THE HELICOPTER OVERTURNING HE OBSERVED THAT 'ONE OF THE ELASTOMERIC SPHERICAL THRUST BEARINGS WAS COMPLETELY GONE.' THE HELICOPTER SUBSEQUENTLY OVERTURNED, SANK AND HAS NOT BEEN RECOVERED. THE ACFT'S ROTOR SYSTEM HAD PREVIOUSLY BEEN INVOLVED IN A SUDDEN STOPPAGE MISHAP AND HAD THEREAFTER BEEN REPAIRED AND RETURNED TO SERVICE BY OTHER THAN THE CURRENT COMPANY MAINTENANCE PERSONNEL.

## Aircraft

- Registration: [N350AP](https://openairdocs.org/deregistered/N350AP-1997-10-09), registration cancelled 1997-10-09, S/N 1252 (OpenAirDocs)
- Reported make and model: AEROSPATIALE AS350B
- Registry model: [Aerospatiale AS350B](https://openairdocs.org/model/aerospatiale-as350b) (registry code 8680800) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1252
- Airframe hours: 1955
- Engines: TURBOMECA ARRIEL 641 horsepower turbo shaft
- Damage: Destroyed
- Flight: Part 135
- Operator: Micronesian Aviation Corp., doing business as Macaw Helicopters
- Last inspection: 100 hour, March 31, 1990, 4 hours before
- Departed: KOBLERVILLE, OF
- Destination: ANATAHAN ISLAND, OF
- Flight plan: Company VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 28; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; flight hours: 6,975 total, 675 in this make and model, 6,775 as pilot in command, 147 in the last 90 days, 89 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 10 knots, gusting 12
- Visibility: 35 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19900401065499A](https://openairdocs.org/incident/19900401065499A), Apr 1, 1990: Snias AS350B, Saipan, Northern Mariana Islands, Destroyed. Vibration and warning horn. Ditched in ocean and sank. A main rotor head thrust bearing had seperated. Prior damage

## Other investigations on N350AP (1)

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.

- [NTSB NYC87LA220](https://openairdocs.org/ntsb/NYC87LA220), Jul 28, 1987: Aerospatiale AS350D (N350AP), Nantucket, MA, substantial damage

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.