Pilot Debrief

GASTON THOMAS D THUNDER MUSTANG near Council, ID — 2014-10-03

Final reportWPR15LA001
Sign in to save
Date
2014-10-03
Location
Council, ID, USA
Airport
U82
Aircraft
GASTON THOMAS D THUNDER MUSTANG
Registration
N51TG
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Approach

Probable cause

The pilot's failure to maintain control while maneuvering for landing following a loss of oil pressure. Contributing to the accident was foreign material contamination of the oil system due to improper maintenance.

Contributing factors

Contributing to the accident was foreign material contamination of the oil system due to improper maintenance.

NTSB narrative

The pilot/builder had not flown his experimental amateur-built airplane for several months while he performed a top overhaul of the engine. During the first flight after completion of the overhaul, a witness observed the pilot start the airplane, complete an engine run-up, and take off uneventfully. Shortly thereafter, the pilot radioed that he was having an engine oil pressure issue and was returning to the airport. The witness then observed the airplane on the downwind leg of the traffic pattern. The airplane turned onto the base leg about "1/2 mile closer than normal," and, upon turning onto the final leg of the traffic pattern, began a series of descending S-turns. The airplane then made a "hard" right turn away from the runway and impacted rocky terrain. The airplane was destroyed, and the pilot was fatally injured. Postaccident examination of the engine revealed foreign material in the oil consistent with the remnants of blue paper shop towels. This contamination was likely the cause of a low oil pressure indication. Recorded data indicated that the engine experienced a loss of oil pressure about two minutes before the accident. All other recorded parameters revealed no anomalies, with the engine indicating about 2,000 rpm at the time of impact, which may suggest that the pilot was trying to limit internal damage to the engine by reducing its power setting. Given the witness account of the airplane turning onto the base leg closer than normal, it is possible that the observed s-turns on the final leg of the approach, as well as the turn away from the runway, were an attempt to lose altitude and speed so that the airplane could be landed on the runway. It is likely that the pilot's preoccupation with the low oil pressure indication contributed to a loss of control while maneuvering for landing. Toxicological testing of the pilot was positive for diphenhydramine; however, there was no evidence to suggest that this may have contributed to the accident.

Analysis

Primary failure mode
Engine power loss
First missed decision gate
Pilot could have aborted the approach upon reporting low oil pressure.

NTSB coding

Evidence available

  • ADS-B / radar
  • 14 docket documents
View NTSB final reportView NTSB docket

Docket documents14

Related mishaps