Casualties unknown

1996-04-28: Cessna 320 (N5752X) — Mammoth Lakes, CA

Mammoth Lakes, CA, US

On April 28, 1996, a Cessna 320 (registration N5752X) was involved in an aviation accident near Mammoth Lakes, CA. Investigators recorded the probable cause as: the partial failure of the right engine turbocharger wastegate butterfly valve to fully close due to mechanical binding and the low setting of its associated absolute pressure controller. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

During takeoff at a high-elevation airport, the right engine failed to produce adequate manifold pressure, causing the aircraft to veer right and settle in rough terrain. Examination revealed turbocharger issues.

Incident Overview

A pilot conducted a static engine run-up prior to takeoff, noting no discrepancies. During the initial climb, at an altitude between 25 and 50 feet above the runway, the left engine produced the expected 35 inches of manifold pressure (MP), but the right engine only produced between 18 and 20 inches of MP. The airplane subsequently veered to the right and descended into rough, uneven terrain near the airport.

Environmental Conditions

The airport elevation was 7,128 feet mean sea level. The calculated density altitude exceeded 8,200 feet, indicating reduced engine performance capability due to high density altitude.

Post-Accident Examination

Inspection of the right engine's turbocharger assembly revealed two anomalies. The absolute pressure controller was set lower than the manufacturer's specifications required. Additionally, the wastegate butterfly valve was mechanically binding in its housing and would not fully close. These conditions likely prevented the right engine from developing normal power.

Conclusion

The source does not provide an explicit probable cause. The findings indicate that the right engine's turbocharger assembly was not functioning within manufacturer specifications, contributing to a loss of power during takeoff.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001208X05623. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.