# Accident 19980627015189A: Scwzer G164B, Oakdale, WA, June 27, 1998

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: June 27, 1998, 06:30 local time
- Place: Oakdale, WA
- Damage: Substantial damage
- Phase of flight: Forced/Precautionary Landing
- Operating rules: Agricultural (Part 137)
- Operator: NRVG
- Location: 47.1194° N, 117.2492° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=47.1194&lon=-117.2492&mi=10
- Aircraft: N7502C, registered now (https://openairdocs.org/aircraft/N7502C) (OpenAirDocs)
- Registry model: Schweizer G-164B (registry code 8059055, https://openairdocs.org/model/schweizer-g-164b) (OpenAirDocs)
- Registry engine: Pratt & Whitney R1340 series (registry code 52016, https://openairdocs.org/engine/pratt-whitney-r1340-series) (OpenAirDocs)
- Reported make and model: SCWZER G164B
- People aboard: 1
- Fatal injuries: 0
- Pilot flight hours: 19,400 total, 600 in this make and model, 200 in the last 90 days
- NTSB investigation: [NTSB SEA98LA106](https://openairdocs.org/ntsb/SEA98LA106) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19980627015189A

## Narrative

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

LOST POWER ON TAKEOFF. NO FURTHER INFORMATION.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  (.4)ACCORDING TO THE PILOT, DURING TAKEOFF, APPROXIMATELY 10 FEET ABOVE THE GROUND, THE AIRCRAFT STARTED BACKFIRING AND LOSING POWER. HE ABORTED THE TAKEOFF, BUT WAS UNABLE TO GET THE AIRCRAFT STOPPED BEFORE IMPACTING A DITCH JUST OFF THE DEPARTURE END OF THE AIRSTRIP. A POST-ACCIDENT INSPECTION OF THE ENGINE BY AN FAA AIRWORTHINESS INSPECTOR FOUND THAT A PORTION OF THE NUMBER THREE CYLINDER HEAD CASTING THROUGH WHICH THE EXHAUST VALVE ROCKER PIN PASSES HAD FRACTURED. THIS ALLOWED THE NUMBER THREE CYLINDER EXHAUST VALVE TO REMAIN IN THE CLOSED POSITION DURING THE TIME THAT IT SHOULD HAVE BEEN OPEN, RESULTING IN A LOSS OF POWER. THE ROCKER BOX CASTING WAS SENT TO THE NTSB METALLURGICAL LABORATORY FOR FURTHER ANALYSIS. THAT EXAMINATION REVEALED THAT THE FRACTURE IN THE CASTING WAS THE RESULT OF A FATIGUE CRACK THAT ORIGINATED IN THE WALL OF THE HOLE IN THE CASTING THROUGH WHICH THE ROCKER ARM PIVOT BOLT PASSED.  IT COULD NOT BE DETERMINED WHAT CAUSED THE FATIGUE CRACK TO INITIATE.

## 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 SEA98LA106](https://openairdocs.org/ntsb/SEA98LA106), Jun 27, 1998: Schweizer G-164B (N7502C), Oakdale, WA, substantial damage. Probable cause: A fatigue failure of the number three cylinder exhaust rocker box assembly, compromising the ability of the exhaust valve to operate. Factors include a ditch at the end of the runway.

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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