NTSB Reports
Aviation Safety Intelligence
Premium research interface

The modern interface for aviation safety intelligence.

Search investigations, review source evidence, monitor watched reports, and trace long-term patterns from one calm, data-first workspace.

Get the iPhone App
63k+
Reports indexed
1940-2026
Coverage
Recent
Last data refresh
Featured Report

Loading…

Loading featured report…

Loading…
Open Report

Safety trends by operating rule

Track fatal and non-fatal accident patterns across Part 91, Part 135, and Part 121 operations.

Loading trend charts…

Browse the aviation graph

Move quickly by aircraft, airport, operator, and time with indexes built for research, not wandering.

Last Data Update

By Decade

By Month

Aircraft Manufacturer

More manufacturers

Airports

More airports

Operators

More operators

About

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.

The goal is practical safety education: make it faster to find relevant investigations, compare similar events, review factual records, and understand the evidence behind probable-cause and preliminary reports.

The investigative work and source records belong to the National Transportation Safety Board and the published investigation record. This site is not affiliated with or endorsed by the NTSB.

FAQs

NTSB Report

August 19, 1991 · Cessna U206F · N35831

Nimrod, OR

Overview

Report Status
Probable Cause
Event Type
Accident
Date
August 19, 1991
Injury Outcomes
No injuries (2 uninjured)
Location
Nimrod, OR
Aircraft
Cessna U206F
Tail Number
N35831
Operator
Evergreen Helicopters
Injuries
None
Aircraft Damage
Substantial
NTSB Number
SEA91LA212

WHILE IN CRUISE FLIGHT THE ENGINE BEGAN RUNNING ROUGH AND ULTIMATELY SEIZED. THE PILOT EXECUTED A FORCED LANDING DURING DARK NIGHT CONDITIONS ONTO ROUGH AND UNEVEN TERRAIN WITHIN A LOGGING CLEARCUT AREA. DURING THE ROLLOUT THE NOSE GEAR WAS SHEARED OFF AND THE AIRCRAFT NOSED OVER TO AN INVERTED POSITION RESULTING IN SUBSTANTIAL DAMAGE. SUBSEQUENT DISASSEMBLY OF THE ENGINE REVEALED A FATIGUE CRACK WHICH GENERATED INTO A FRACTURE OF THE CRANKSHAFT. THE CRACK WAS OBSERVED TO EMANATE FROM THE OIL TUBE PASSAGE HOLE IN THE NUMBER FOUR SHORT CHEEK OF THE CRANKSHAFT.

NTSB Probable Cause

THE FRACTURED CRANKSHAFT RESULTING IN ENGINE SEIZURE FOLLOWED BY A FORCED LANDING ON ROUGH AND UNEVEN TERRAIN RESULTING IN SEPARATION OF THE NOSE GEAR.

Full Narrative

WHILE IN CRUISE FLIGHT THE ENGINE BEGAN RUNNING ROUGH AND ULTIMATELY SEIZED. THE PILOT EXECUTED A FORCED LANDING DURING DARK NIGHT CONDITIONS ONTO ROUGH AND UNEVEN TERRAIN WITHIN A LOGGING CLEARCUT AREA. DURING THE ROLLOUT THE NOSE GEAR WAS SHEARED OFF AND THE AIRCRAFT NOSED OVER TO AN INVERTED POSITION RESULTING IN SUBSTANTIAL DAMAGE. SUBSEQUENT DISASSEMBLY OF THE ENGINE REVEALED A FATIGUE CRACK WHICH GENERATED INTO A FRACTURE OF THE CRANKSHAFT. THE CRACK WAS OBSERVED TO EMANATE FROM THE OIL TUBE PASSAGE HOLE IN THE NUMBER FOUR SHORT CHEEK OF THE CRANKSHAFT.

Flight

Event TypeAccident
Event Time21:30 PDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftCessna U206F
Tail NumberN35831
Aircraft CategoryAir
DamageSubstantial
OperatorEvergreen Helicopters
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsContinental · IO-520-F · Reciprocating · 300
Seats6

People & Injuries

Injury SummaryNo injuries (2 uninjured)
Fatal0
Serious0
Minor0
Uninjured2
Total2
Crew 1Age 30 · First Class

Conditions

ConditionsVMC
LightDark Night
Wind260° @ 10 kt
Visibility15 sm
CeilingNone
Temperature / Dew Point0 C / 0 C
Altimeter0
Observation Time03:54
Weather SourceWFAC

External Links

Appendix: Source Data