NTSB Factual Report

"***This report was modified on March 20, 2017. Please see the docket for this accident to view the original report.***

HISTORY OF FLIGHT

On October 3, 2014, about 1330 mountain daylight time (MDT), an experimental Thomas D Gaston, Thunder Mustang, N51TG, crashed during approach to landing at the Council Municipal Airport, Council, Idaho. The owner/pilot was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The airline transport pilot was the sole occupant, and sustained fatal injuries; the airplane was destroyed by impact forces. The local personal flight departed Council at an undetermined time. Visual meteorological conditions prevailed, and no flight plan had been filed.

Witnesses reported that during a flight after the pilot had performed maintenance on the engine, the pilot radioed that he was having an engine oil pressure issue, and was returning to the airport.

One witness observed the airplane flying a normal pattern until he turned base closer to the airport than normal. He then observed the airplane as it turned on to final making descending "S" turns, he then saw the airplane make a very hard right turn towards the North-Northeast about 100 feet above the ground. He watched the airplane as it flew away from the airport when he lost sight of it.

PERSONNEL INFORMATION

A review of Federal Aviation Administration (FAA) airman records revealed that the 75-year old pilot held an airline transport pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. The pilot also held a repairman experimental aircraft builder certificate.

The pilot held a third-class medical certificate issued on June 30, 2014. It had the limitations that the pilot must wear corrective lenses for distant vision, and possess glasses for near vision.

No personal flight records were located for the pilot. The investigator in charge obtained the aeronautical experience listed in this report from a review of the FAA airmen medical records on file in the Airman and Medical Records Center located in Oklahoma City, Oklahoma. The pilot reported on his medical application that he had a total time of 18,500 hours with 25 hours logged in the last 6 months.

AIRCRAFT INFORMATION

The airplane was an experimental amateur built Thomas D Gaston, Thunder Mustang, serial number EITM027. A review of the airplane's logbooks revealed that the airplane had a total airframe time of 222.8 hours at the last conditional inspection dated July 1, 2013.

The last entry in the aircraft logbook was dated October 2, 2014, the day before the accident. The entry was for a conditional inspection, and was signed by the pilot/builder but no aircraft times were recorded in the entry.

The engine was a Falconer V-12, serial number 12027. Total time on the engine at the last inspection was unrecorded, and could not be determined; time since major overhaul was 0.0 hours. The engine logbook had an entry dated October 2, 2014, stating the engine was test run, and safe for flight.

The engine was equipped with two MoTec M48 Engine Control Units (ECU). The units were recovered and sent to the NTSB recorders lab for download.

COMMUNICATIONS

The accident pilot was overheard on the airport UNICOM frequency by witnesses at the airport. The pilot reported he was returning due to low oil pressure. No other communication from the pilot was heard.

WRECKAGE AND IMPACT INFORMATION

Investigators from the FAA examined the wreckage at the accident scene. The accident site was in a rocky field, about 1/3 of a mile northwest of the approach end of runway 17.

The first identified point of contact (FIPC) was a ground scar. The airplane impacted the ground at a shallow angle, and the fuselage broke apart as it slid approximately 60 feet along a heading of 318° true. The engine broke loose from the airframe and slid another 15 feet. The gear reduction case and propeller hub continued another 25 feet with one blade intact and largely undamaged. There was no rotational damage noted to the propeller.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy was completed at the request of the Adams County Coroner on October 4, 2014. The coroner ruled the manner and cause of death to be a result of blunt force trauma due to an aircraft accident. No significant natural disease was identified by autopsy. The FAA's Bioaeronautical Research Sciences Laboratory, Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot.

Analysis of the specimens contained no findings for carbon monoxide, and volatiles. They did not perform tests for cyanide.

The report contained the following findings for tested drugs: 0.034 (ug/ml) diphenhydramine detected in blood cavity..

TESTS AND RESEARCH

The airplane engine was equipped with two engine control units (ECU) which were recovered and sent to the NTSB recorders lab for download. The NTSB lab specialist submitted a factual report which is attached to the docket for this accident.

A summary of the findings of the ECU's revealed that the engine lost oil pressure 110 seconds prior to the accident. The recorded engine RPM increased and decreased in correlation with the recorded throttle position throughout the flight. The engine RPM at impact was 2,000 RPM. All the other recording parameters appeared normal until time of impact.

Examination of the recovered engine was conducted on October 7, 2015, at the facilities of Air Transport Inc. in Phoenix Arizona. A report of the examination is attached to the accident docket.

No evidence of preimpact mechanical malfunction was noted during the examination of the recovered engine.

The lower oil pan was removed and the bottom end of the engine was visually examined with no signs of thermal damage or oil starvation identified.

A foreign substance was found in the oil pan and throughout the oil cavity consistent with shredded blue paper shop towels which had been mixed in with the oil.

Review of the aircraft records revealed limited entries as to the detail of work being done on the airframe or engine.

Additional information regarding the work done on the airplane or engine by the pilot/mechanic was obtained by conversations with witnesses without any supporting documents from the aircraft records.

NTSB 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.