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
May 23, 1990 · Hughes 269C · N7441F
Rialto, CA
Overview
Report Status
Probable Cause
Event Type
Accident
Date
May 23, 1990
Injury Outcomes
No injuries (1 uninjured)
Location
Rialto, CA
Aircraft
Hughes 269C
Tail Number
N7441F
Injuries
None
Aircraft Damage
Substantial
NTSB Number
LAX90LA187
THE HELICOPTER ENCOUNTERED GROUND RESONANCE DURING A MAINTENANCE TEST FLIGHT. THE CFI NOTICED AN UNUSUAL VIBRATION DURING STUDENT TRAINING. THE PILOT SUSPENDED THE TRAINING AND INFORMED MAINTENANCE. THE PILOT THEN ATTEMPTED TO DUPLICATE THE VIBRATION FOR ONE OF THE MAINTENANCE MECHANICS. AFTER TWO UNSUCCESSFUL ATTEMPTS, THE PILOT LANDED THE HELICOPTER ON A SLIGHT SLOPE. AFTER ONE SKID TOUCHED DOWN, THE HELICOPTER BEGAN TO VIBRATE. THE PILOT REDUCED THE THROTTLE AND THE VIBRATION BECAME MORE SEVERE. ACCORDING TO THE PILOT, THE HELICOPTER BEGAN TO DISINTEGRATE.
NTSB Probable Cause
IMPROPER MAINTENANCE PROCEDURE BY MAINTENANCE PERSONNEL TO TROUBLESHOOT A REPORTED DEFICIENCY AND THE PILOT'S DECISION TO DEMONSTRATE THE VIBRATION, EXCEEDING THE DESIGN LIMITS OF THE HELICOPTER AND INDUCING GROUND RESONANCE. CONTRIBUTING TO THE ACCIDENT WAS THE LOW NITROGEN CHARGE OF THE LANDING GEAR DAMPERS.
Full Narrative
THE HELICOPTER ENCOUNTERED GROUND RESONANCE DURING A MAINTENANCE TEST FLIGHT. THE CFI NOTICED AN UNUSUAL VIBRATION DURING STUDENT TRAINING. THE PILOT SUSPENDED THE TRAINING AND INFORMED MAINTENANCE. THE PILOT THEN ATTEMPTED TO DUPLICATE THE VIBRATION FOR ONE OF THE MAINTENANCE MECHANICS. AFTER TWO UNSUCCESSFUL ATTEMPTS, THE PILOT LANDED THE HELICOPTER ON A SLIGHT SLOPE. AFTER ONE SKID TOUCHED DOWN, THE HELICOPTER BEGAN TO VIBRATE. THE PILOT REDUCED THE THROTTLE AND THE VIBRATION BECAME MORE SEVERE. ACCORDING TO THE PILOT, THE HELICOPTER BEGAN TO DISINTEGRATE.
Flight
Event TypeAccident
Event Time11:10 PDT
Nearest AirportRIALTO (0nm N)
Runway0
Flight Plan FiledUnknown
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftHughes 269C
Tail NumberN7441F
Aircraft CategoryHeli
DamageSubstantial
Operating RulePart 91
Engines1
Engine TypeReciprocating
Engine DetailsLycoming · HIO-360-D1A · Reciprocating · 190
Seats2
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 42 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind270° @ 5 kt
Visibility20 sm
CeilingNone
Temperature / Dew Point0 C / 0 C
Altimeter0