LAX04LA254 · Eurocopter AS-350-B2
Eurocopter AS-350-B2 · Accident: loss of control in flight en route
From Scottsdale Airport (KSDL) to an unrecorded destination
Event
- NTSB case
- LAX04LA254
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Eurocopter AS-350-B2
- Aircraft type
- Eurocopter AS-350
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N513TS
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Scottsdale Airport (KSDL), Scottsdale, AZTo not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · descent
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of control in flight
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Other maintenance personnel › Maintenance, installation, improper
- Pilot in command › Remedial action, not possible
- Rotorcraft flight control, collective control › Locked
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
While performing a maintenance check flight, the collective down lock engaged, which resulted in an uncontrolled descent and collision with terrain. The pilot and a mechanic were to fly a maintenance flight check of the engine and perform a rotor track and balance. He entered a descent at approximately 1,200 feet above ground level (agl) and prepared to level off at approximately 700 feet agl. When he tried to pull up on the collective, the collective would not move and was observed latched by the collective down lock. He and the mechanic tried to unlatch the collective from the down lock, but they did not have enough time before he had to flare the helicopter for landing. With the collective stuck in flat pitch, they landed hard and with forward speed. The flight crew evacuated the helicopter once it had come to rest. An ensuing post accident fire destroyed the helicopter. A new after market avionics control panel had been installed and the collective down lock, which is secured to the panel, was adjusted prior to the flight. The down lock attaches to the lower section of avionics panel. When the collective is lowered to the lower pitch stop the clearance between the collective and the down lock is about 0.16 inches. The down lock is a flexible plate that is free to vibrate with the helicopter's normal rhythms. In the original factory installation, the clearance between the down lock and the collective is 0.3 inches. This is the second known accident where the collective lock has inadvertently engaged in flight with this particular after market avionics panel installed. The manufacturer of the aftermarket avionics panel provided installation information indicating that maintenance personnel must bend the collective locking plate such that the locking plate will spring away from the collective lock button. Examination of the accident aircraft’s locking plate indicated that the locking plate bend was likely reversed, allowing the locking plate to spring toward the lock button.
Probable cause
Inadvertent in-flight engagement of the collective down lock, which resulted in an uncontrolled descent and ground impact. The collective down lock engagement was caused by the improper installation and/or adjustment of the collective locking system, which reduced the clearance between the locking plate and the collective control. A factor was the pilot’s decision to embark on a maintenance test flight after encountering difficulty disengaging the collective lock release during previous hover tests.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX04LA254
- Event ID
- 20040708X00933
- Case number
- LAX04LA254
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 545fe408ae3833a25b8ae6606c72d0dd9673a44171627c5d26d0da87b2d4c1de; retrieved 2026-09-21T19:12:36.603Z.