NTSB Factual Report

HISTORY OF FLIGHT

On December 16, 2014, about 1620 mountain standard time, a Piper PA-18-150 Super Cub, N5989Z, impacted a hill while maneuvering in Ronan, Montana. The commercial pilot was fatally injured, and the pilot-rated passenger sustained serious injuries; the airplane sustained substantial damage. The local personal flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91, and departed Ronan Airport, Ronan, Montana about 1600. Daytime visual meteorological conditions prevailed, and no flight plan had been filed.

The passenger was a student pilot, and had purchased the airplane about 6 weeks prior to the accident. He had recently purchased a new propeller for the airplane and the pilot, who was also an aviation mechanic, installed the propeller just prior to the accident flight. After departure they maneuvered around the local area with the pilot acting as pilot-in-command the entire flight. As they approached the hills they were checking the performance of the airplane. The pilot stated that he saw a coyote and performed a wingover maneuver. The airplane banked left and the pilot pulled up. With the airplane about 20 feet away from the terrain the pilot stated "I don't think we are going to make it." The airplane collided with terrain. The passenger reported that there were no pre impact mechanical malfunctions or failures that would have precluded normal operation.

Numerous witnesses reported observing the airplane maneuvering at a low altitude a few minutes prior to the accident. One witness recalled hearing the airplane's engine accelerate and rev higher just prior to the impact. Another witness stated that he observed the airplane perform several erratic maneuvers which began with the airplane close to the ground, followed by a rapid climb and descent, similar to an agricultural operation (crop dusting).

PERSONNEL INFORMATION

Pilot

A review of the airmen records maintained by the Federal Aviation Administration (FAA) disclosed that the pilot, age 33, held a commercial pilot certificate with ratings for single-engine land, single engine sea, and instrument airplane. The pilot additionally held his mechanic's certificate with an airframe and powerplant rating. His most recent second-class medical certificate was issued without limitation on June 27, 2014.

The pilot's personal flight logbooks were not recovered. According to his last application for an FAA medical certificate, he reported a total flight time of 3,000 hours, 120 of which he accumulated in the 6 months prior to the medical examination.

Passenger

A review of the passenger's airmen records disclosed that he held a student pilot certificate which he received in October 2014. The passenger's logbooks indicated that he had amassed about 40 hours of total time all in the accident airplane, with his first solo occurring about a month prior to the accident.

AIRCRAFT INFORMATION

The Piper PA-18-150 Super Cub, serial number (s/n) 18-8247, was manufactured in 1965 and equipped with a Lycoming Engine O-320-A2B, s/n L-15095-27A. The passenger purchased the airplane in October 2014. He reported that the most recent annual inspection of the airframe and engine was performed on September 12, 2014.

The pilot had installed a Brorer 82/42 propeller on the engine just prior to the accident.

METEOROLOGICAL INFORMATION

A routine aviation weather report (METAR) generated by an Automated Surface Observation System (ASOS) at the Missoula International Airport, located about 40 miles south of the accident site, indicated that about 30 minutes before the accident the conditions were as follows: wind was from 280 degrees at 4 knots; temperature -01 degrees Celsius; dew point -07 degrees Celsius; overcast at 6,000 ft; and altimeter 29.98 inHg.

According to the U.S. Naval Observatory, about the time of the accident, the sun was about 3 degrees above the horizon, on an azimuth of about 230 degrees, and local sunset occurred at 1647.

WRECKAGE AND IMPACT

The airplane wreckage was located on a steep easterly-facing hillside, about 100 feet below the peak located on a 45-degree slope. The accident site was about 5 nautical miles from Ronan Airport, on a bearing of about 295 degrees. The wreckage came to rest on a hillside in the Valley View Hills, which is the most easterly elevated terrain from the valley where both the towns of Pablo and Ronan are located. The surrounding area was sparsely populated. There were ground scar signatures in the terrain, consistent with the propeller and left wing tip colliding with terrain at the initial impact. These first identified impact points were about 75 feet from the main wreckage. The debris field was oriented on a heading of about 200 degrees. The airplane's wreckage was found inverted with the nose pointed upslope.

MEDICAL AND PATHOLOGICAL INFORMATION

The Montana State Forensic Science Division in Missoula, Montana conducted an autopsy of the pilot. The FAA Civil Aeromedical Institute (CAMI) performed toxicological screenings on the pilot. According to CAMI's report (#201500001001) the toxicological findings were negative for carbon monoxide and ethanol; Ibuprofen was detected in urine samples.

TESTS AND RESEARCH

Flight control continuity was established from the cockpit area to the control surfaces. An external visual examination of the engine revealed that it remained attached to the engine mounts. The engine case and accessories sustained deformation from impact energy forces. The right fuel tank contained a near full tank of liquid consistent in odor and appearance to that of aviation fuel.

The propeller remained attached to the engine's crankshaft. The propeller blades displayed leading edge gouging, torsional twisting, chordwise striations across the cambered surface, and trailing edge "S" bending. The signatures were consistent with the absorption of rotational forces applied at the crankshaft at the time of impact.

There was no evidence of pre impact mechanical malfunction or failure.

Global Positioning System (GPS) Data

A Garmin Aera 796 multi-function display and GPS receiver was found in the wreckage. The previous flights were all conducted east of the accident location. A download and review of the data with accompanying depictions of the flight track is contained in the NTSB public docket for this accident. The data included 13 track logs dating from December 7, 2014, through the accident flight 9 days later.

The data revealed that the airplane departed Ronan at 1607, and the last data point was recorded at 1619:19. After departure, the airplane turned toward the west just prior to reaching the town of Pablo, Montana and continued climbing. At 1611 the airplane had climbed to 3,500 ft mean sea level (msl) and began turning to the northwest. The terrain elevation in this area was approximately 3,100 ft msl. After making a 360-degree turn and continuing northwest, at around 1616, the airplane turned toward the west and then southbound. The airplane proceeded southbound towards rising terrain. At 1619, at an altitude of 3,450 ft msl, the airplane began a turn toward the east. Comparison of the recorded altitude and ground track with terrain elevation data revealed that the track was consistent with the airplane maneuvering about 100 ft above ground level (agl). The last data point was recorded at 1619:19, and was located about 3,765 ft west of the accident site. That data point indicated that at that time, the airplane was at an altitude of 3,501 ft msl (100 ft agl) and a ground speed of 72 kts.

NTSB Probable Cause

The pilot’s failure to maintain clearance from terrain while performing an intentional, abrupt low-level maneuver.