NTSB Factual Report

HISTORY OF FLIGHT

On April 3, 2015, about 1230 Pacific daylight time, an experimental amateur built Quicksilver Enterprises Inc. MXL II, N476VB, was destroyed when it impacted terrain near the Petaluma Municipal Airport (O69), Petaluma, California. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The student pilot, sole occupant of the airplane, was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The local flight originated from O69 at an unknown time.

One witness, who was located on the first tee at the Adobe Creek Golf Course, reported that they observed the accident airplane flying over their position about 1,000 feet above ground level (agl). He thought it was too windy for a small airplane to be flying as he estimated the wind was from the north, about 15 to 20 miles per hour (mph). A short time later, the witness had moved to the second tee, when he saw the accident airplane pointed directly into the wind along a northerly heading toward O69. The witness recalled that it "did not seem to making headway," and appeared to remain in the same position relative to the ground until about 20 seconds later, when the airplane entered a slow left 180-degree turn. The witness heard the sound of the engine increase as he stopped watching the airplane for a few seconds. Shortly after, he heard the engine noise stop and looked up, observing the airplane "falling straight [down] out of the sky" with both wings appearing upward, as if they had collapsed or folded in the middle. Subsequently, the airplane descended below a tree line.

A second witness, who was playing golf at the Adobe Creek Golf Course, northeast of the accident site, reported that he saw the airplane flying in an easterly direction; it flew over the vineyard, and turned right to the west into the wind. He looked down, hit a ball, looked up, and saw the airplane at a 45-degree angle, both wings folded upward; the airplane immediately entered a spin, and descended into the ground. The witness recalled that the wind was blowing fairly strong, estimating about 10 to 20 mph with gusts to 20 mph or more. The witness stated that he recalled that it wasn't a good day for flying the ultralights.

A third witness reported that he was located on a walking trail by the water treatment plant, and was watching the accident airplane fly around the area. The witness said that following a turn, the airplane suddenly descended in an almost vertical attitude while appearing to be traveling "very fast", followed by both wings folding upward.

PERSONNEL INFORMATION

The pilot, age 51, held a student pilot certificate, which was issued on January 23, 2014.

Review of the pilot's personal logbook revealed that as of the most recent logbook entry dated March 29, 2015, he had accumulated 66 hours total flight time, 65.1 hours in the accident make/model airplane, 36.2 hours of solo flight time, of which 3.8 hours were within the previous 30 days, and 7 hours within the previous 60 days of the accident.

According to Federal Aviation Administration (FAA) files, the pilot had first applied for a medical certificate in 2003. At that visit, the aviation medical examiner (AME) documented he had a "rather abrupt manner, quite tense and emotionally labile mood. Tangential, but not confused." In addition, he had scarring and limited range of motion of this left elbow. Although the pilot had not initially reported any significant medical history, he eventually told the AME he had had a severe head injury. The pilot's certificate was deferred, and the FAA eventually denied his application.

The pilot's last application for a medical certificate was dated December 3, 2004. At that time, he reported 45 total flight hours, and reported his head injury, admission to hospital, and disability as a result. He also reported that he had severe injuries of the left elbow with joint replacement. The AME deferred his certificate; the FAA requested additional information from the pilot regarding his injuries, requested he undergo a neurocognitive evaluation, and provide the results to them. The results indicated he had below average visual processing speed, normal intellectual ability, and no impairments in executive functioning, speech perception, or verbal judgment. However, the pilot failed to provide all the requested information to the FAA, and his certificate was eventually denied.

AIRCRAFT INFORMATION

The two-seat, high-wing, fixed-gear airplane, serial number (S/N) 062, kit was built in 1984. It was powered by a Rotax 503 engine, rated at 50 horsepower. The airplane was also equipped with a whirlwind two bladed composite propeller.

Review of the airframe and engine logbooks revealed that the most recent conditional inspection was completed on November 12, 2014, at a tach time of 28.23 hours. The most recent maintenance conducted on the airplane was completed on March 24, 2015, at a tach time of 45.34 hours, which included installation of a 4.5 gallon seat fuel tank.

METEOROLOGICAL INFORMATION

A review of recorded data from the Gnoss Field Airport (DVO) automated weather observation station, located about 6 miles west of the accident site, revealed at 1235 conditions were wind from 300 at 4 knots, visibility 10 statute miles, clear sky, temperature 19 degrees C, dew point 5 degrees C, and an altimeter setting of 30.20 inches of mercury.

WRECKAGE AND IMPACT INFORMATION

Examination of the accident site revealed that the airplane impacted an open field adjacent to a tree line about 1.3 miles southeast of runway 29. The airplane came to rest in a near vertical position. All major structural components were present at the accident site. Debris, including the engine and one propeller blade, were located within about 15 feet of the main wreckage.

The left wing remained partially attached to the airframe via both the flying wires and landing wires, however, it was separated at the forward spar attach point. The forward spar was separated about mid span. The fracture surface was consistent with overload and impact damage. In addition, all of the internal braces for the left wing were separated. One of the internal brace wires was found separated, and exhibited splayed signatures, consistent with overload. The wing covering was mostly intact, but torn in various areas. No scuffing or transfer marks were observed on either the top or bottom side of the wing. The left aileron remained attached to its respective mounts.

The right wing remained attached to the airframe via the forward spar mounts and all of the flying and landing wires. The forward spar was bent and twisted in numerous areas, consistent with impact. In addition, all of internal braces for the right wing were separated. The wing covering was mostly intact and turn in various areas. No scuffing or transfer marks were observed on either the top or bottom side of the wing. The right aileron remained attached via its respective mounts.

The empennage remained intact and undamaged. The horizontal and vertical stabilizers remained attached to their respective mounts. The rudder and elevators remained attached to their respective mounts.

Flight control continuity was established from all primary flight controls to the cockpit controls.

The airframe was mostly impact damaged. The instrument panel was separated with numerous instruments dislodged. The right side flying wires remained attached to the seat structure; however, the left side flying cables were separated by first responders.

The airframe was equipped with a ballistic parachute system. The parachute was found dislodged from one half of the parachute case; however, it was extended about 15 feet from the main wreckage. The envelope of the parachute remained stowed within the opposing half of the case.

The engine was separated from the airframe, and located about 15 feet from the main wreckage. The carburetors and the propeller gearbox were separated from the engine. The propeller hub and one of the two propeller blades remained attached to the propeller gearbox and located within the main wreckage. The separated propeller blade was found about 10 feet from the main wreckage. The separated propeller blade exhibited a nick in the leading edge near the blade tip. The nick was found consistent with the size of a landing wire utilized on the airplane. Both the left and right carburetors were separated. When the float bowls were removed, the internal floats were found intact and undamaged. The needle valves for both carburetors and valve seats were intact and undamaged. The engine crankshaft was rotated, and compression was obtained on both cylinders.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy performed at the request of the Sonoma County Coroner's Office by Forensic Medical Group determined the cause of death was multiple extreme blunt force injuries due to a light plane crash, and the manner of death was an accident. No significant natural disease was identified, however, the examination of the brain was limited by the extent of injury.

In a note regarding the death investigation, the investigator reported they had interviewed the pilot's ex-wife who believed the decedent changed his name due to the fact he really wanted to fly, and could not due to a traumatic brain injury he received, which would exclude him from getting a pilot's license. The investigator also noted that the pilot was receiving supplemental security income disability benefits under the social security number and the different name than what the airplane and student pilot certificate were issued under.

Toxicology testing performed by NMS Laboratories at the request of the Coroner identified tetrahydrocannabinol (THC, the psychoactive component in marijuana) at 3.3 ng/ml in cavity blood. Levels of the primary metabolite, tetrahydrocannabinol carboxylic acid (THC-COOH) were less than 5.0 ng/ml.

Toxicology testing performed by the FAA's Bioaeronautical Research Laboratory identified diphenhydramine, tetrahydrocannabinol (THC), and tetrahydrocannabinol carboxylic acid (THC-COOH; 0.0873 ug/g) in liver. In addition, diphenhydramine (0.634 ug/ml), THC (level below 1 ng/ml), and THC-COOH (0.004 ug/ml; 4 ng/ml) were identified in cavity blood. THC (level below 1 ng/g) and THC-COOH (0.0059 ug/g; 5.9 ng/g) were identified in the lung.

Diphenhydramine is a sedating antihistamine used to treat allergy symptoms and as a sleep aid. It is available over the counter under the trade names Benadryl and Unisom. Diphenhydramine carries the following FDA warning: may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating heavy machinery). Compared to other antihistamines, diphenhydramine causes marked sedation; this is the rationale for its use as a sleep aid. Altered mood and impaired cognitive and psychomotor performance may also be observed. In fact, in a driving simulator study, a single dose of diphenhydramine impaired driving ability more than a blood alcohol concentration of 0.100%. The therapeutic range for diphenhydramine is 0.0250 to 0.1120 ug/ml.

Diphenhydramine undergoes post mortem redistribution where after death, the drug can leech from storage sites back into blood. Central post mortem levels may be about two to three times higher than peripheral levels.

Although now available for medicinal use in some states and has been decriminalized in limited amounts in others, marijuana continues to be labeled as a Schedule 1 Controlled Substance by the Drug Enforcement Administration. It has mood altering effects including inducing euphoria and relaxation. In addition, marijuana causes alterations in motor behavior, perception, cognition, memory, learning, endocrine function, food intake, and regulation of body temperature. Specific performance effects include decreased ability to concentrate and maintain attention, impairment of hand-eye coordination, and is dose-related over a wide range of dosages. Impairment in retention time and tracking, subjective sleepiness, distortion of time and distance, vigilance, and loss of coordination in divided attention tasks have been reported.

Interpreting post mortem blood and tissue results for marijuana is complex for several reasons. First, the drug is lipophilic, and gets stored in fatty tissues; it undergoes post mortem redistribution, and may leech back into blood from liver, lung, and brain after death. Thus, post mortem testing may not indicate ante-mortem levels. Marijuana has been demonstrated to have clinical effects at levels as low as 0.001 ug/ml. While significant performance impairments are usually observed for at least 1-2 hours following marijuana use, and residual effects have been reported up to 24 hours, even when the blood level is undetectable.

TESTS AND RESEARCH

Portions of the left and right wing spars were sent to the NTSB Materials Laboratory for further examination. A senior metallurgist examined the spars, and reported that the right spar exhibited a separation about 53 inches from the inboard end. The deformation pattern of the spar tubes at and adjacent to the separation were consistent with bending deformation. Optical examination of the fracture at the separation revealed features consistent with overstress separations following approximately 45 degrees of deformation. No indications of preexisting cracking or corrosion were apparent.

The left wing spar was fractured about 96 inches from the inboard end. The fracture and adjacent deformation were consistent with a tension bending separation. No indications of preexisting cracking or corrosion were apparent.

NTSB Probable Cause

The pilot's failure to maintain control of the airplane while maneuvering, which resulted in an uncontrolled descent and structural failure. Contributing to the accident was the pilot's impairment from his use of diphenhydramine.