ERA14FA461

The pilot's decision to fly the improperly balanced helicopter at high speed and low altitude, which resulted in a loss of control and collision with terrain. Contributing to the accident were the pilot's depression and resulting degradation of executive function and the pilot's use of a sedating antihistamine, which resulted in impaired mental and motor skills.

The private pilot of the experimental amateur-built, single seat, helicopter departed his home airport, flew to a friend's property, and landed uneventfully. After his visit, the pilot started the helicopter, lifted off, and departed to the southwest. About 1 minute later, his friend observed the helicopter coming toward him in a nose-low attitude, about 400 ft above ground level, and at a "high rate of speed." The helicopter suddenly pitched over, began to tumble, and impacted in an inverted attitude; a postcrash fire ensued. Sound spectrum analysis of a video of the accident flight indicated that the helicopter was flying at an airspeed of at least 83 knots when the loss of control occurred. The pilot did not possess a rotorcraft helicopter rating. Review of the pilot's logbook revealed entries that indicated the pilot had been endorsed for solo flight in the Robinson R22 and had flown an R22 solo. However, according to the flight instructor who had given the pilot about 21 hours of flight instruction in an R22, he had not endorsed the pilot for solo flight in the R22, and he had observed that the pilot had some "bad habits" and would occasionally lose control of the helicopter. It is likely that the pilot made the logbook entries to indicate that he had soloed because they were required by the helicopter kit manufacturer before he could receive a factory checkout of the helicopter, which he had purchased about 6 months before the accident. The factory checkout was conducted on the day before the accident. According to the factory check pilot, during the checkout, the pilot kept making mistakes and advised the check pilot that he was very tired because he had not slept for 2 days due to anticipation of the checkout. Also, during the checkout, the check pilot determined that the weight and balance of the helicopter was not correct, and the pilot would need to fly the helicopter so they could check the position of the cyclic stick during hover. The pilot advised the check pilot that, because of his lack of sleep and nervousness, he did not feel it safe to fly the helicopter that day. As a result, the check pilot reminded him that he would need to check the weight and balance and the position of the cyclic stick during hover before operating the helicopter, since it was not accomplished that day. Examination of the wreckage did not reveal evidence of any preimpact failures or malfunctions of the helicopter or engine that would have precluded normal operation. A piece of angle iron was discovered in the debris field, which, according to the pilot's friend, the pilot had attached to the helicopter's tailboom for weight and balance purposes. However, calculations revealed that the helicopter's center of gravity was outside the forward edge of the weight and balance envelope approved by the kit manufacturer. It is likely that the out of balance condition combined with the high speed of the low-altitude pass resulted in the loss of control. The pilot had therapeutic levels of the antidepressant sertraline in his blood at the time of the accident. Although any psychoactive medications can be impairing, sertraline is not known to directly cause sleepiness or other impairing symptoms. Therefore, it is unlikely that effects from sertraline impaired the pilot. However, sertraline is prescribed for treatment of depression, and major depression itself is associated with significant cognitive degradation, particularly in executive functioning. The cognitive degradation may not improve even with remission of the depressed episode, and patients with severe disease are more significantly affected than those with fewer symptoms or episodes. The pilot demonstrated poor decision-making and executive function when he decided to fly the helicopter without having soloed in the R22 and without adequately addressing the identified issue with the helicopter's weight and balance. Additionally, flying the helicopter at high speed and low altitude further demonstrated his impaired executive function. One month before the accident, the pilot's personal physician described inappropriate demeanor and unkempt appearance; this is the most recent description of the pilot's executive function and further suggests the depression was not well controlled. Therefore, the pilot's depression and resulting degradation of executive function likely contributed to his decision to fly the poorly balanced helicopter in a high-speed, low-altitude maneuver and contributed to the accident. The pilot had provided his aviation medical examiner (AME) with a letter from his physician documenting his anxiety/depression as well as its treatment. According to Federal Aviation Administration (FAA) guidance, depression treated for less than 6 months is disqualifying, and a medical certificate should not have been issued. Therefore, the investigation determined the AME failed to follow FAA guidelines for depression and inappropriately provided the pilot with a medical certificate. The AME forwarded the records of the pilot's depression to the FAA 19 days before the accident; therefore, there was insufficient time for the FAA to identify the issue and recall an improperly issued medical certificate. Additionally, the pilot had used diphenhydramine before the accident. Compared to other antihistamines, diphenhydramine causes marked sedation. Altered mood and impaired cognitive and psychomotor performance may also be observed. The diphenhydramine in cavity blood tested by two laboratories was not consistent (0.828 and 2.171 ug/ml), but the results were well above the therapeutic range of 0.0250 to 0.1120 ug/ml. Diphenhydramine undergoes postmortem redistribution, and postmortem central blood levels may increase by about three times with cavity blood levels even higher. However, even divided by seven or eight, the postmortem levels measured suggest that the pilot likely had impairing levels at the time of the accident. Although the pilot had been able to fly the helicopter for a short distance earlier in the day, the subsequent high-speed pass with the helicopter outside of weight and balance specifications required a much higher degree of flight skill to complete safely. Therefore, the pilot's use of diphenhydramine likely degraded his flight skills and contributed to his inability to safely control the helicopter.

The helicopter was not equipped with a cockpit voice recorder or flight data recorder, nor was it required to be by federal regulations. However, a camcorder that was being operated by the pilot's friend whose property the accident occurred on captured most of the liftoff and accident flight. Five files from the camcorder were provided to the NTSB. Each file contained video and audio of the helicopter on the day of the accident; however, only two of the five files were used by investigators. (The remaining three files did not have sufficient content for analysis.) The audio was extracted from each file at its native sample rate of 48,000 kHz and converted to a mono wave file for sound spectrum analysis. The first video, which was 26 seconds long, captured the pilot seated inside the helicopter with the engine powered on at the start of the video with the observer directly facing the helicopter. The helicopter began a hover from standstill at 8 seconds and then started moving forward 4 seconds later. The helicopter flew past the observer at 21 seconds and continued off into the distance. Only the last 12 seconds of this file were used for sound spectrum analysis. The second video, which was 11 seconds long, captured the helicopter coming towards the observer from a distance. The helicopter was heard passing by the camera when the camera panned out at 6 seconds. An unidentified sound was heard, and the camera panned back to the helicopter at 8 seconds and showed the helicopter descending in an inverted attitude until impact. A spectrogram was generated for the extracted audio track of each file. The frequencies associated with the turbine and main rotor rpm were identified from the first file and used as a baseline of analysis for second file. Doppler effect was present in the first file and was used to calculate airspeed during forward flight. Evaluation of Takeoff The main rotor frequency was determined to be 20.3 Hz, which resulted in a main rotor rpm of about 615 rpm. This value remained constant before and after passing the observer. The speed of the helicopter as it passed the observer was estimated to be 33 knots. The frequencies identified were consistent with a normal takeoff under takeoff power. Evaluation of Event In the second video, the airspeed was determined to be about 83 knots. The orientation between the observer and the helicopter could not be established; therefore, the actual airspeed may have been higher than calculated. The main rotor frequency was determined to be between 20.3 Hz and 23.3 Hz, which resulted in a main rotor rpm of about 699 rpm at its peak. The ratio of the calculated rpm to the nominal main rotor rpm (from the first video) was 113%. Pilot's Rotorcraft Forum Posts The pilot was a member of an internet rotorcraft forum and posted regularly. On September 19, 2014, he posted that he had flown the Helicycle about 3 hours that day but still needed the factory check pilot "to come and help me work out little kinks here and there, but overall the flight was great." During the flight, he noticed that there was "a little stick shake" and "had a problem with belt slippage" that he attributed to oil leaking from the transmission filter housing onto the belts. He stated that the factory check pilot was going to come out to install new elastomeric bearings on the rotor hub, and he was sure that "we will balance and tweak everything." Elastomeric Bearings According to the kit manufacturer, the elastomeric bearings were excluded from the purchase price of a Helicycle kit. The elastomeric bearings, which were part of the Helicycle rotor hub and necessary to operate the helicopter, would be withheld from the kit until the kit was assembled and ready for the customer's factory checkout. The installation of the elastomeric bearings would be performed by an authorized factory test pilot during the factory checkout, and the kit manufacturer reserved the right to withhold the elastomeric bearings until the customer had sufficiently prepared for the factory checkout. In the case of the accident helicopter, the Helicycle had been purchased from a previous owner so it already had the elastomeric bearings installed when the pilot purchased it. On September 27, 2014, the elastomeric bearings were replaced to track and balance the main rotor during the pilot's factory checkout. Kit Manufacturer's Requirements for Flight According to the kit manufacturer, their policy was that customers would agree to have a factory checkout performed on their Helicycle before flight. The factory checkout consisted of a multi-day process during which the Helicycle was "checked out" and then test flown by a factory check pilot. During the checkout, the customer also will fly the Helicycle for the first time. The factory checkout would only be scheduled following the receipt of the following items by the kit manufacturer: - Proof of aircraft registration. - Airworthiness certificate. - A completed factory checkout checklist. - Proof of solo flight in the pilot's logbook. Factory Checkout The pilot had contacted the check pilot about 2 months before the accident and advised him that he had purchased a previously owned Helicycle and needed a "checkout." The check pilot advised him that he would be able to do one, but the pilot would have to meet the factory requirements and have a helicopter-rotorcraft certificate or an endorsement for solo in a Robinson R22 helicopter. The pilot advised him that he had not soloed yet but was working on it. The pilot later contacted the check pilot and stated that he had received an endorsement for solo in the Robinson R22 helicopter. As such, the check pilot made arrangements to do the checkout at M33 where the pilot had a hangar where he kept the helicopter. On September 27, 2014, the check pilot met the pilot at M33. Per the check pilot's instructions, the pilot had not installed the main rotor blades on the helicopter as he needed them off the helicopter to make it easier to install the new elastomeric bearings in the rotor head. The check pilot and the pilot installed the new bearings and then re-installed the rotor blades. Before they began the dynamic balancing of the rotor system, the check pilot reviewed the preflight check with the pilot. According to the check pilot, the checklist was similar to most helicopters where you check mechanical components, control linkages, and control operation. During the review, he showed and explained to the pilot how to check all the items on the checklist. They next attached a dynamic rotor blade balancer to the helicopter, rolled the helicopter out of the hangar, and began balancing the main rotor blades. During the blade balancing, the pilot was in the helicopter and was in charge of starting the helicopter, engaging the blades, and running the helicopter up to flight speed, so that balance readings could be taken. (Balancing is done on the ground not in the air.) The check pilot noticed that the pilot was having trouble remembering the correct starting procedure, kept referring to a start procedure that he had printed up to help him, but still kept making mistakes. The pilot told the check pilot that he was very tired because he had not slept for 2 days due to the anticipation of having the checkout done. They performed about seven starts and shutdowns before the dynamic balancing was complete. They then removed the balancing equipment. In the paperwork from the previous owner, the pilot found a weight and balance sheet that showed the helicopter was balanced for a 200-pound (lbs) pilot. Because there was a difference between the check pilot's weight (180 lbs) and the pilot's stated weight of 200 lbs, they added 10 lbs of ballast weight on the floor of the helicopter. Next, they rolled the helicopter out to the taxiway. The check pilot then started the helicopter and began to do some hover testing