Mcdonnell Douglas Helicopter 500N accident near Los Alamitos, California, October 16, 2009
On October 16, 2009 at about 5:45 pm local time, a Mcdonnell Douglas Helicopter 500N, registered N521HB, was substantially damaged in an accident during landing (flare/touchdown) near Los Alamitos, California (Los Alamitos Army Airfield). It was a public-use flight (local) under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The flight instructor's delayed remedial action during the instructional autorotative landing, which resulted in a failure to maintain an adequate rotor rpm to avoid a hard landing.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 16, 2009 · about 5:45 pm local time
- Place
- Los Alamitos, California · Los Alamitos Army Airfield · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Mcdonnell Douglas Helicopter 500N · all 500Ns on the register
- Registration
- N521HB · no longer on the register · serial LN084
- Damage
- Substantial damage
- Flight
- Public-use flight (local) · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The certified flight instructor (CFI) and the pilot he was instructing were practicing emergency procedures, in particular, power recovery autorotations. At 700 feet above ground level (agl), the CFI rolled the throttle off (idle) and entered the autorotation. At 50 feet agl he rolled the throttle on late, realized the ground was rapidly approaching, and decided to perform a running landing. The pilot reported that he inadvertently applied partial throttle, which did not allow the engine to regain full power. With the throttle positioned at 25 percent, the rotor rpm decayed, and when the helicopter contacted the ground, a rotor blade dipped down and struck the tail boom. The pilot stated that the helicopter and engine had no mechanical failures or malfunctions during the flight.
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
What happened, in order
- Simulated/training event during maneuvering
- Autorotation Attempted remediation/recovery
- Hard landing during landing (flare/touchdown) defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Prop/rotor parameters › Not attained/maintained
- Personnel issues › Task performance › Use of equip/info › Use of equip/system › Pilot
- cause Personnel issues › Action/decision › Action › Delayed action › Instructor/check pilot
Flight instructor
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; rotorcraft: helicopter
- Flight time: 1,841 hours in all; 1,790 in this make and model; 140 in the last 90 days; 46 in the last 30 days; 1,792 as pilot in command; 335 on instruments
- Last flight review: December 20, 2007
- Medical certificate: Class 2
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 8,780 hours
- Last inspection: 100-hour inspection, August 10, 2009
- Maximum gross weight: 3,350 lb
- Seats: 4
- Landing gear: fixed
- Engine: Allison 250-C20 SER (turboshaft); 0 hours total
- Operator: City Of Huntington Beach
The flight
- Departed from: CL65 Huntington Beac CA at 4:45 pm
- Destination: KSLI Los Alamitos CA
- Flight plan: none
- Runway 22L, 8,000 ft by 200 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: at 3 knots
- Visibility: 6 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 66°F (19°C)
- Altimeter: 29.89 inHg
- Observation at 5:55 pm from SKLI
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 |
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.
Other NTSB records under N521HB the same tail number, which may have belonged to a different aircraft at the time
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number WPR10TA025.