CEN12LA343 · Schweizer 269C
Schweizer 269C · Accident: ground resonance during landing
From Rocky Mountain Metropolitan Airport (BJC) to Rocky Mountain Metropolitan Airport (BJC)
Event
- NTSB case
- CEN12LA343
- 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
Schweizer 269C
- Aircraft type
- Schweizer 269
- 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
- N2196F
- Operator
- TYJ Global
- Onboard fatalities
- Unknown
- Route
- From Rocky Mountain Metropolitan Airport (BJC), Denver, COTo Rocky Mountain Metropolitan Airport (BJC), Denver, CO
- 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
- Landing
- Defining eventThe 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
- Ground resonance
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft systems
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot reported that, during an introductory flight, he was conducting a 2-foot hover in the helicopter. An airplane started to taxi in front of the helicopter, so the pilot set the helicopter back down on the ground, left skid first and then the right. The helicopter drifted right as the skid made contact, and the pilot added left cyclic input to remedy the drift as he also lowered the collective. As the skids started to settle apart, the pilot noticed a low frequency vibration that immediately got worse. He determined that the helicopter was entering ground resonance, but the engine and collective parameters were too low to lift the helicopter off of the ground, as indicated in the helicopter's operating procedures. The pilot reduced the throttle to idle and "within seconds, the helicopter had shaken itself apart."
Postaccident testing revealed that all four landing gear dampers failed to meet the manufacturer's serviceable testing specifications, and two dampers were overcharged. Maintenance records indicated that the front dampers had been replaced with overhauled units about 10 months and about 534 flight hours before the accident. The aft dampers had been replaced with overhauled units about 7 months and about 280 flight hours before the accident. A review of the manufacturer's overhaul procedure for the landing gear dampers revealed that the procedure used by the overhaul facility did not include functional testing of the dampers following overhaul, which would have identified the out-of-specification condition before installation. Maintenance procedures required periodic inspection of the landing gear dampers, and the operator stated that the 100-hour inspection procedure was accomplished about 1 month before the accident. The mechanic who accomplished this inspection reported that he used the manufacturer's procedures to complete the inspection. However, the out-of-specification damper conditions were not detected.
As a result of this and a similar accident (CEN12LA353), the helicopter manufacturer has committed to revising the overhaul manual to include testing procedures and criteria for overhauled landing gear dampers.
Probable cause
The inadequately overhauled landing gear dampers that allowed initiation of a ground resonance event from which the pilot was unable to recover. Contributing to the accident was the overhaul facility's failure to identify the overcharged dampers and a lack of any published acceptance testing criteria for the dampers in the manufacturer's overhaul procedure manual, resulting in the out-of-specification dampers being provided to the operator. Also contributing was the ineffective damper inspection conducted by the operator's maintenance personnel.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN12LA343
- Event ID
- 20120606X72957
- Case number
- CEN12LA343
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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: 2a01a4bb3e8d34cf8902b584cf283fe4dc13cd2cab344db50bdf2195cab3136b; retrieved 2026-09-15T18:25:26.059Z.