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Aviation safety reports, made easier to study

NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.

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December 29, 1989 · Mcdonnell Douglas 369E · N1604L

Santa Rosa, CA

Overview

Report Status
Probable Cause
Event Type
Accident
Date
December 29, 1989
Injury Outcomes
5 injuries (1 fatality, 1 serious injury, 3 minor injuries)
Location
Santa Rosa, CA
Aircraft
Mcdonnell Douglas 369E
Tail Number
N1604L
Operator
Interwest
Injuries
Fatal
Aircraft Damage
Destroyed
NTSB Number
LAX90FA060

THE PILOT EXECUTED AN IMMEDIATE LEFT DOWNWIND CLIMBING TURN WHEN HE DEPARTED THE HELIPAD AND EXPERIENCED A LOSS OF TAIL ROTOR EFFECTIVENESS. BEFORE DEPARTING, THE PILOT FAILED TO ACCOUNT FOR THE DOWNWIND TURN AND THE HELICOPTER'S EXCEEDING THE MAXIMUM GROSS WEIGHT. THE POST ACCIDENT INVESTIGATION DISCLOSED THE LATERAL TRIM MOTOR EXCEEDED ITS PHYSICAL EXTENSION LIMITS WHICH INDICATES THAT THE TRIM MOTOR WAS OPERATING DURING THE IMPACT SEQUENCE WHEN ITS AIRFRAME ATTACHMENT POINT WAS BROKEN.

NTSB Probable Cause

THE PILOT'S IMPROPER PREFLIGHT PLANNING/DECISION WHICH RESULTED IN THE LOSS OF TAIL ROTOR EFFECTIVENESS. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT ALLOWING THE MAXIMUM GROSS WEIGHT OF THE AIRCRAFT TO BE EXCEEDED, AND THE TAILWIND.

Full Narrative

THE PILOT EXECUTED AN IMMEDIATE LEFT DOWNWIND CLIMBING TURN WHEN HE DEPARTED THE HELIPAD AND EXPERIENCED A LOSS OF TAIL ROTOR EFFECTIVENESS. BEFORE DEPARTING, THE PILOT FAILED TO ACCOUNT FOR THE DOWNWIND TURN AND THE HELICOPTER'S EXCEEDING THE MAXIMUM GROSS WEIGHT. THE POST ACCIDENT INVESTIGATION DISCLOSED THE LATERAL TRIM MOTOR EXCEEDED ITS PHYSICAL EXTENSION LIMITS WHICH INDICATES THAT THE TRIM MOTOR WAS OPERATING DURING THE IMPACT SEQUENCE WHEN ITS AIRFRAME ATTACHMENT POINT WAS BROKEN.

Flight

Event TypeAccident
Event Time11:30 PST
Nearest AirportSonoma County (0nm N)
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftMcdonnell Douglas 369E
Tail NumberN1604L
Aircraft CategoryHeli
DamageDestroyed
OperatorInterwest
Operating RulePart 91
Engines1
Engine TypeTurboshaft
Engine DetailsAllison · 250-C20 · Turboshaft · 375
Seats5

People & Injuries

Injury Summary5 injuries (1 fatality, 1 serious injury, 3 minor injuries)
Fatal1
Serious1
Minor3
Uninjured0
Total5
Crew 1Age 34 · First Class

Conditions

ConditionsVMC
LightDaylight
Wind310° @ 5 kt
Visibility30 sm
CeilingNone
Temperature / Dew Point59 / 37 C
Altimeter30.00 inHg
Observation Time19:32
Weather SourceWFAC

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Appendix: Source Data