LAX07LA274 · Robinson R22 Beta
Universal Air Academy Robinson R22 Beta · Accident: airframe, component or system failure en route
From San Gabriel Valley Airport (EMT) to San Gabriel Valley Airport (EMT)
Event
- NTSB case
- LAX07LA274
- 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
Robinson R22 Beta
- Aircraft type
- Robinson R22
- 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
- N877HF
- Operator
- Universal Air Academy
- Onboard fatalities
- Unknown
- Route
- From San Gabriel Valley Airport (EMT), El Monte, CATo San Gabriel Valley Airport (EMT), El Monte, CA
- 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 · cruise
- 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
- Airframe, component or system failure
- 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
- Electrical system, drive/belt › Failure
- Rotor drive system, main rotor drive belt › Failure, total
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
While in cruise flight about 1,700 feet agl, the flight instructor heard a loud "bang" from the back of the helicopter. The alternator warning light illuminated, and he initiated the alternator emergency procedure. He noticed the engine's rpm was fluctuating with the main rotor rpm indicating high and the engine rpm low. He entered an autorotation and landed on uneven terrain; the main rotor struck the tail boom, and the helicopter rolled over onto its left side. The helicopter was examined by a Safety Board investigator. The two main drive V-belts were located in the drive compartment with one positioned on the drive pulleys in the middle slot (between the normal operating positions for the forward and aft belts), and the other was located completely off of the drive pulleys. Both belts exhibited damage on the inside including scratch marks, material and color transfers, and gouges consistent with damage by a rubber based foreign object. Rubber and color transfer in a transverse orientation inconsistent with the drive belts was noted on the upper and lower pulleys. The alternator belt was missing and not recovered. The clutch assembly was located in the up position with the actuator fully extended, and the safety stop activated. The oil cooler sustained damage to the outer fins. Rubber transfer was located on the oil cooler, starter, oil lines, and exhaust tube on a plane with the alternator belt's rotation. The alternator belt is located directly below the lower main drive pulley. No other preimpact anomalies with either the airframe or engine were discovered. As a result of this investigation Robinson is changing the specification for the alternator drive belt.
Probable cause
a failure of the main rotor drive system V-belts due to damage sustained when the alternator drive belt failed and pieces of that belt got between the main drive belts and their associated pulleys. A contributing factor was the uneven terrain encountered in the forced landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX07LA274
- Event ID
- 20070927X01461
- Case number
- LAX07LA274
- 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: 3fe11aa4658f51b123fcb584ce8d35160213c5f38cb27d7cf9c06e4f6e5e9a4b; retrieved 2026-09-22T03:25:34.103Z.