Overall Trends
Total, fatal, and serious accidents in the selected range.
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.
63k+
Reports indexed
1940-2026
Coverage
Recent
Last data refresh
Search everything
Fast key and full-text search with live filters, watches, and precise metadata.
Use quotes for exact phrase matches (for example "fuel selector valve").
Featured 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…
High-signal investigations
Major cases, deep-report coverage, and investigation media across decades of NTSB history.
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 manufacturersAirports
More airportsOperators
More operatorsAbout
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 7, 1991 · Texas Helicopter M74L · N51855
Lodi, CA
Overview
Report Status
Probable Cause
Event Type
Accident
Date
August 7, 1991
Injury Outcomes
1 injury (1 minor injury)
Location
Lodi, CA
Aircraft
Texas Helicopter M74L
Tail Number
N51855
Operator
Sierra Helicopter Services
Injuries
Minor
Aircraft Damage
Substantial
NTSB Number
LAX91LA351
IN HIS WRITTEN STATEMENT, THE PILOT SAID THAT SHORTLY AFTER LIFTOFF HE HEARD A LOUD BANG AND 'ALL DIRECTIONAL CONTROL WITH THE CYCLIC WAS LOST.' HE NOTED THAT THE HELICOPTER PITCHED SLIGHTLY TO THE RIGHT AND IMPACTED IN A CORN FIELD. THE HELICOPTER WAS EXAMINED IN DETAIL BY AN FAA AIRWORTHINESS INSPECTOR FROM THE OAKLAND, CALIFORNIA, FLIGHT STANDARDS DISTRICT OFFICE. ACCORDING TO THE INSPECTORS REPORT, HE IDENTIFIED NO MECHANICAL PROBLEMS WITH THE ENGINE, DRIVE TRAIN OR CONTROL SYSTEM. FUEL WAS FOUND IN THE TANKS, LINES AND THE CARBURETOR. HE SAID THAT HE FOUND NO EVIDENCE OF A SPRAY BOOM OR ROTOR BLADE STRIKE PRIOR TO GROUND IMPACT. THE INSPECTOR NOTED THAT THE GROUND CONTRACT MARKS WERE CONSISTENT WITH A NEARLY LEVEL ATTITUDE GROUND IMPACT, WITH ABOUT 70 FEET OF STRAIGHT GROUND SCARS.
NTSB Probable Cause
THE INFLIGHT LOSS OF CONTROL BY THE PILOT FOR UNDETERMINED REASONS.
Full Narrative
IN HIS WRITTEN STATEMENT, THE PILOT SAID THAT SHORTLY AFTER LIFTOFF HE HEARD A LOUD BANG AND 'ALL DIRECTIONAL CONTROL WITH THE CYCLIC WAS LOST.' HE NOTED THAT THE HELICOPTER PITCHED SLIGHTLY TO THE RIGHT AND IMPACTED IN A CORN FIELD. THE HELICOPTER WAS EXAMINED IN DETAIL BY AN FAA AIRWORTHINESS INSPECTOR FROM THE OAKLAND, CALIFORNIA, FLIGHT STANDARDS DISTRICT OFFICE. ACCORDING TO THE INSPECTORS REPORT, HE IDENTIFIED NO MECHANICAL PROBLEMS WITH THE ENGINE, DRIVE TRAIN OR CONTROL SYSTEM. FUEL WAS FOUND IN THE TANKS, LINES AND THE CARBURETOR. HE SAID THAT HE FOUND NO EVIDENCE OF A SPRAY BOOM OR ROTOR BLADE STRIKE PRIOR TO GROUND IMPACT. THE INSPECTOR NOTED THAT THE GROUND CONTRACT MARKS WERE CONSISTENT WITH A NEARLY LEVEL ATTITUDE GROUND IMPACT, WITH ABOUT 70 FEET OF STRAIGHT GROUND SCARS.
Flight
Event TypeAccident
Event Time12:30 PDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftTexas Helicopter M74L
Tail NumberN51855
Aircraft CategoryHeli
DamageSubstantial
OperatorSierra Helicopter Services
Operating RulePart 137
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · VO-435-A1E · Reciprocating · 250
Seats1
People & Injuries
Injury Summary1 injury (1 minor injury)
Fatal0
Serious0
Minor1
Uninjured0
Total1
Crew 1Age 45 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind270° @ 3 kt
Visibility50 sm
CeilingNone
Temperature / Dew Point70 F / 0 C
Altimeter0
Weather SourcePILO