Bell 205A-1 accident near Los Angeles, California, March 23, 1998
On March 23, 1998 at about 3:40 pm local time, a Bell 205A-1 (helicopter), registered N90230, was destroyed in an accident near Los Angeles, California. It was a public-use flight under general aviation rules (Part 91). 4 people were killed and 2 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
An excessive bending load applied to the tail rotor blade assembly of an undetermined origin which produced a fatigue crack, the separation of the assembly, and a forced landing. Factors were the lack of suitable terrain to perform a forced landing, the manufacturer's unclear maintenance bulletin instruction and procedures which facilitated the operator's inadequate inspection for the yoke's straightness, and the inadequacy of restraint systems and protective equipment.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 23, 1998 · about 3:40 pm local time
- Place
- Los Angeles, California · map
- Type
- Accident
- Injuries
- 4 people were killed and 2 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 205A-1 · all 205A-1s on the register
- Registration
- N90230 · no longer on the register · serial 30221
- Damage
- Destroyed
- Flight
- Public-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During an air ambulance flight in the public-use helicopter, the tail rotor and gearbox separated from the helicopter. The pilot autorotated to a forced landing. During the descent over mountainous terrain, the helicopter collided with trees and impacted hard terrain on its left side which crushed inward. The operator's policy required all crewmembers to wear helmets during flight. Helmets were not provided for the two paramedics. During the crash sequence, the passenger seat stanchions and tubing buckled, which resulted in multiple lap belt anchor point separations and the catapulting of crewmembers into the overhead cockpit panel. Safety Board survival factors documentation in conjunction with helmet crashworthiness analysis revealed helicopter impact forces were within human tolerance. The lack of and/or inadequate strength helmets and the lap belt anchor point failures allowed crewmembers' excursions resulting in head trauma. The tail rotor component separations in flight resulted from a fatigue crack originating in the surface of the yoke onto which the tail rotor blades had been attached. In 1996, Bell issued an Alert Service Bulletin (ASB) number 205-96-68, which was designed to measure yoke deformation resulting from adverse in-flight or ground handling operations which imposed excessive bending loads. The test protocol was found problematic in its accuracy due to technical errors in the bulletin and a lack of clarity. City mechanics failed to adhere to all of the ASB's requirements. The bent yoke fractured at a total time in service of approximately 4,113 hours, about 117 hours after its inspection for evidence of deformation. The yoke's stainless steel composition and requisite metallurgical properties were confirmed by the Safety Board. An x-ray diffraction examination of the yoke revealed reduced compressive residual stress in the fracture origin region which allowed operational loads to initiate and propagate the fatigue crack. This significant reduction of the residual stress was likely due to excessive flexure (bending) of the yoke. The initiating event which overstressed and bent the yoke was not identified.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: helicopter; rotorcraft: helicopter
- Flight time: 1,570 hours in all; 219 in this make and model; 21 in the last 90 days; 15 in the last 30 days; 1,498 as pilot in command; 120 on instruments
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 5,115 hours
- Last inspection: annual inspection, January 12, 1998; 18 hours since
- Maximum gross weight: 10,200 lb
- Seats: 15
- Landing gear: fixed
- Engine: Lycoming T5313B (turboshaft); 0 hours total
- Fire on the ground
- Operator: Los Angeles City Fire Dept.
The flight
- Departed from: Los Angeles CA at 3:33 pm
- Destination: Los Angeles CA
Weather at the time
- Light: daylight
- Visibility: 20 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 50°F (10°C)
- Altimeter: 30.00 inHg
- Observation at 3:47 pm from BUR, 6 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 | 2 | ||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.