# Accident 19970625040829A: Enstrm F28F, Riverside, CA, June 25, 1997

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: June 25, 1997, 12:43 local time
- Place: Riverside, CA
- Airport: Riverside Municipal
- Damage: Substantial damage
- Phase of flight: Forced/Precautionary Landing
- Operating rules: General operating rules (Part 91)
- Location: 33.9000° N, 117.4003° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=33.9000&lon=-117.4003&mi=10
- Aircraft: N99YC, a cancelled registration (https://openairdocs.org/deregistered/N99YC-2018-01-24) (OpenAirDocs)
- Registry model: Enstrom F-28F (registry code 3300412, https://openairdocs.org/model/enstrom-f-28f) (OpenAirDocs)
- Registry engine: Lycoming HIO-360 series (registry code 41524, https://openairdocs.org/engine/lycoming-hio-360-series) (OpenAirDocs)
- Reported make and model: ENSTRM F28F
- Reported engine: LYC HIO360*
- Fatal injuries: 0
- Pilot flight hours: 2,500 total
- NTSB investigation: [NTSB LAX97LA224](https://openairdocs.org/ntsb/LAX97LA224) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19970625040829A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

ENGINE QUIT ON CLIMBOUT 200 FT AGL UNABLE AUTO LANDED HARD. INTAKE VALVE ROCKER SHAFT CAME LOOSE. NEW ENGINE. (.4) DURING TAKEOFF, THE HELICOPTER LOST POWER AND LANDED HARD. POSTACCIDENT EXAMINATION REVEALED THE NO. 2 CYLINDER INTAKE VALVE ROCKER SHAFT MIGRATED OUT OF THE SHAFT BOSSES OF THE CYLINDER HEAD. THE SHAFT, COVER, AND NUTS WERE FOUND; THE WASHERS WERE NOT.  ACCORDING TO OWNER/PILOT THERE WERE INTERNAL STAR WASHER IMPRINTS ON THE COVER PLATE COMMONLY CAUSED BY TORQUE OR TIGHTENING OF THE NUT.  THE HELICOPTER HAD 61.5 TOTAL HOURS SINCE NEW, AND RECEIVED ONE 50-HOUR INSPECTION SINCE DELIVERY TO THE OWNER/PILOT.  THE OWNER/PILOT CHANGED THE OIL AND FILTER JUST PRIOR TO THE INSPECTION.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB LAX97LA224](https://openairdocs.org/ntsb/LAX97LA224), Jun 25, 1997: Enstrom F-28-F (N99YC), Riverside, CA, substantial damage. Probable cause: failure by unknown maintenance personnel to retorque the nuts on the retainer cover.

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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