# NTSB Accident LAX91LA137
> **SIKORSKY H-19/S55** · 1991-03-19 · RICHVALE, CA, USA · NONE
## Event
- **NTSB number:** LAX91LA137
- **Event ID:** 20001212X16635
- **Type:** Accident
- **Date:** 1991-03-19
- **Location:** RICHVALE, CA, USA
- **Coordinates:** 39.479099, -121.839874
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 1
- **Total aboard:** 1
## Aircraft
- **Make:** SIKORSKY
- **Model:** H-19/S55
- **Registration:** N9894
- **FAR Part:** 137
- **Engines:** 1
- **Damage:** SUBS
## Conditions
- **Light:** DAYL
- **Weather:** VMC
## Probable cause

THE FAILURE OF THE ENGINE'S NUMBER 4 CYLINDER INTAKE VALVE KEEPER.  TREES UNDER THE HELICOPTER AT THE TIME OF THE LOSS OF ENGINE POWER WERE FACTORS IN THE ACCIDENT.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=LAX91LA137) · AI Analytics · CC0 1.0*