Pilot Debrief

BEECH B35 near Orangeburg, SC — 2023-06-10

Final reportERA23FA265
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Date
2023-06-10
Location
Orangeburg, SC, USA
Aircraft
BEECH B35
Registration
N8725A
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Descent

Probable cause

A stuck No. 3 cylinder intake valve, which resulted in a partial loss of engine power and subsequent forced landing.

NTSB narrative

The pilot of the airplane was on a short cross-country flight in visual meteorological conditions and was receiving flight following services from air traffic control. About 20 minutes into the flight, while flying at an altitude of about 1,200 ft above the ground, the pilot advised the air traffic controller that there was a problem with the airplane’s engine. The controller called out the nearest airport to the pilot, which at that point was about 6 miles away and behind him. The pilot responded that the airplane would not be able to reach the airport, and no further transmissions were received from the pilot. The airplane subsequently impacted trees and terrain and a postimpact fire ensued. Postaccident examination of the wreckage revealed that the engine’s No. 3 cylinder intake pushrod was bent, but that the corresponding pushrod tube did not display evidence of any impact-related damage. The corresponding intake valve displayed a buildup of carbon deposits on the valve stem and both the intake and exhaust tappets for the No. 3 cylinder displayed abnormal wear. All of these signatures suggest that the No. 3 cylinder intake valve may have stuck open during the flight. With the valve stuck in an open position, the introduction of exhaust gases into the engine’s air intake system likely would have resulted in a reduction of engine power such that engine was no longer able to produce sufficient thrust to sustain level flight. Review of the airplane’s registration and maintenance records revealed that the pilot had purchased the airplane about 9 months before the accident. Shortly thereafter, while on a long cross-country flight, the airplane’s engine began leaking oil. Maintenance personnel subsequently inspected the airplane and identified numerous discrepancies with the engine related to the leaking oil, as well as leaking and deteriorated exhaust system components (though they did not specifically identify any issues related to the No. 3 cylinder or its intake valve). The records did not reflect that any of the identified discrepancies had been rectified or that the airplane had undergone any other inspections. It is possible that, had the airplane’s engine undergone more extensive inspection, troubleshooting, and repair, issues with the No. 3 intake valve could have been identified and addressed before the accident flight.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have diverted to OGB earlier when engine issues were first noted.

NTSB coding

Evidence available

  • ATC audio
  • ADS-B / radar
  • Photos
  • 12 docket documents
View NTSB final reportView NTSB docket

Docket documents12

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