Mattituck, NY, USA
N79ZR
ZUBAIR S KHAN RAVEN
The airplane departed its home airport for a local flight. Radar data indicated that, about 9 minutes after departure, the airplane was at 7,400 ft mean sea level (msl) and had begun a left 270-degree turn. The last radar return, which was recorded about 1 minute later, showed the airplane about 1,100 ft msl, which correlates to an approximate 6,000 ft-per-minute descent. The airplane was found the following day floating on top of the water in a sound and was subsequently recovered. The pilot's parachute pack was found deployed and partially wrapped around the propeller. The airplane's canopy was not present; however, it was located several weeks later floating in the water. Postaccident examination of the airplane revealed no evidence of any mechanical failure or anomaly that would have precluded normal operation. The airplane's calculated center of gravity (CG) was about 3 inches beyond the aft CG limit, which likely induced longitudinal instability and led to a subsequent deep, unrecoverable stall. The canopy examination and the as-found condition of the parachute pack indicated that the canopy was likely opened in flight. Therefore, the pilot likely recognized that the stall was unrecoverable and attempted to bail out of the airplane but was unsuccessful. Although toxicology testing showed that the pilot had used marijuana at some time before the accident, the low levels detected in the pilot's specimens indicated that he was not likely significantly impaired by its use at the time of the accident.
HISTORY OF FLIGHT On July 6, 2014, about 1905 eastern daylight time, an experimental amateur-built Raven, N79ZR, was substantially damaged when it impacted the water in the vicinity of Mattituck, New York. The private pilot was fatally injured. The airplane was registered to and operated by an individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight originated at Brookhaven Airport (HWV), Shirley, New York, about 1855. The airplane was located floating on top of the water of Long Island Sound, the following morning by a private individual. According to radar data, the airplane was first observed at 1,200 feet above mean sea level (msl) south of HWV. The airplane turned left towards the north and continued to climb to about 8,500 feet msl as it went over the north shoreline and continued flight over Long Island Sound. The airplane subsequently began to descend. At 1904:18, radar data indicated that the airplane was at 7,400 feet msl and began a left 270° turn towards the east. At 1904:33, radar data indicated that the airplane was traveling in an east direction and was at 5,800 feet msl. The last radar return was recorded at 1905:19, and indicated an altitude of about 1,100 feet msl. PERSONNEL INFORMATION The pilot, age 41, held a private pilot certificate for airplane single-engine land issued June 21, 2005, and a third-class airman medical certificate issued June 11, 2013, with no limitations. The pilot's logbook was not recovered for examination. On the pilot's June 11, 2013, Federal Aviation Administration (FAA) medical application, he reported 220 total flight hours. According to a statement provided by a flight instructor, the pilot had satisfactorily completed a flight review on April 6, 2014; however, at the time of the flight review, the pilot's total flight time was not recorded. AIRCRAFT INFORMATION The four-seat, composite canard airplane, with retractable landing gear was manufactured in 2014 and issued an airworthiness certificate on February 7, 2014. It was powered by a Lycoming IO-540-C1A engine driving a Catto Glass Carbon Composite 3-Blade propeller. Review of the aircraft maintenance logbook records showed that a condition inspection was completed on February 7, 2014 at a recorded time of 20.1 hours. The Hobbs meter was not located at the accident site and airframe operating time could not be conclusively determined. The airplane was equipped with a front-hinged canopy which functioned as the front windshield, side windows, and cabin roof. The canopy was the only access to and from the cockpit. A primary latch lever mounted in the cockpit operated four latch pins. Weight and balance information, computed on January 30, 2013, indicated that the airplane's maximum gross takeoff weight was 2,200 pounds and the designed center of gravity (CG) range was 95 to 99.5 inches aft of datum. Utilizing the computed information, the airplane's weight at the time of takeoff was about 1,818 pounds and the CG was 102.2 inches aft of datum. The investigation was not able to determine if the pilot had performed a weight and balance or why he elected to operate the airplane out of CG. METEOROLOGICAL INFORMATION The 1853 recorded weather observation at Westhampton Beach, The Gabreski Airport (KFOK), Westhampton Beach, New York, located about 10 miles to the south of the last recorded radar return, included wind from 220 degrees at 9 knots with gusts of 17 knots, visibility 10 miles, clear skies, temperature 22 degrees C, dew point 17 degrees C, and barometric altimeter 29.98 inches of mercury. WRECKAGE AND IMPACT INFORMATION The wreckage was located at 41°3'53.7" N and 072°41.418" W, about 4 miles north of the north shore of Long Island and about 20 miles northeast of the departure airport. Examination of the airplane by an FAA inspector and a representative from the engine manufacturer revealed damage to fuselage, left wingtip leading edge, and the right canard trailing edge. The damage was consistent with a left wing low attitude when it impacted the water. The pilot had a personal parachute pack, and when recovered, photographic evidence revealed that the parachute had been deployed, remained attached to the pilot, trailing behind the airplane, and wrapped around the propeller. Examination of the canopy brackets attached to the fuselage and both hinges revealed no tearing or shearing of the bolts; however, neither the bolts nor the canopy were present. Flight control continuity was confirmed to all flight control surfaces from the cockpit control, except for the rudders. Rudder continuity was confirmed from the cable fracture point in the vicinity of the rudder pedals to the rudder control surfaces; however, the rudder pedals were absent. The left wing and left canard remained attached to the fuselage. The left wing exhibited leading edge damage which extended from the wingtip inward approximately 4 feet. The nose section exhibited impact damage and was partially fractured on the right side circumferentially around the bottom of the nose but remained partially attached on the left side. The nose wheel remained attached and was partially extended. Examination of the canopy brackets attached to the forward section of the fuselage and both hinges revealed no tearing or shearing of the bolts; however, no bolts nor the canopy were present. The canopy was subsequently located July 9, 2014, floating on top of the water, about 39 miles northeast of the last recorded radar return. The canopy remained intact and the windscreen was not damaged. A video camera remained attached to the canopy; however, no recording of the accident flight was able to be extracted from the camera memory. The canopy quick release mechanism remained attached to the canopy and was found in the released position. The four locking pins and associated locking pin holes exhibited no distortion and were unremarkable. The four pins were reinstalled into the locking pin holes and appeared to lock into place. The quick release line was pulled by an FAA inspector and all four pins released and operated normally. The instrument panel exhibited impact damage but remained attached to the forward portion of the cockpit. The throttle lever handle was impact separated; however, the lower portion of the throttle lever arm remained attached and was in the full forward or "OPEN" position. The mixture lever was in the full forward or full "rich" position. The fuel selector valve was in the "BOTH" position. The landing gear position indicator located aft of the fuel selector valve indicated three "UP" positions. Both ignition switches were found guarded and in the "ON" position. The glareshield included circuit breakers and several switches. The following switches were found in the on position: Master, Radio Master, Landing Light, Strobe Lights, Pitot Heat, Spare Circuit, and Fuel Pump. The left side control stick remained attached to the control column. The left and right cockpit molded seats remained attached and had various fractures located along the back. Both seatbelts and shoulder harnesses remained attached to the associated attach point; however, the right seat belt and should harness had been cut by first responders to facilitate recovery of the occupant. The right wing and right canard remained attached to the airplane. The right rudder remained attached to the winglet at all hinge points. The right aileron remained attached at all hinge points. Both fuel caps remained secured and in place. Each fuel tank indicated a 30 gallon capacity. The aft pusher engine compartment remained attached to the fuselage and the firewall was not damaged. The lower and upper engine cowlings exhibited impact damage but remained attached to the fuselage. The engine assembly remained attached to all engine mounts. The composite three-blade propeller remained attached to the propeller crankshaft flange. The propeller blades were not damaged, and the personal parachute canopy and associated cords were found wrapped around the blades and hub. Examination of the engine assembly revealed that the left and right engine exhaust pipes exhibited impact crush damage at the Nos. 1 and 2 cylinders. All induction tubes were attached to their respective attached points. The throttle cable remained attached to the throttle control arm on the fuel injector servo and was at mid-range. The mixture control remained attached to the mixture control arm and was in the full rich position. The fuel injector servo was removed and contained fuel. The fuel injector servo fuel inlet screen was removed and free of contaminants. The fuel injector servo regulator section was disassembled and no anomalies were noted. The fuel flow divider was removed, disassembled and no anomalies were noted. The fuel injector nozzles were removed from all cylinders and no anomalies were noted. The engine was subsequently partially disassembled. The engine was rotated by hand using the propeller. Suction and compression was obtained on all cylinders. Valve train continuity was observed through all cylinder rocker arms. The accessory drive gears were observed rotating. Crankshaft and valve train continuity was verified. A detailed "Memorandum of Record - Engine Examination Report" with accompanying pictures is contained in the public docket for this investigation. MEDICAL AND PATHOLOCIAL INFORMATION An autopsy was performed on the pilot on July 7, 2014, by Suffolk County Medical Examiner's Office, Hauppauge, New York. The autopsy reported the cause of death as "multiple blunt impact injuries," and the report listed the specific injuries. Forensic toxicology was performed on specimens from the pilot by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The toxicology report stated no carbon monoxide detected in the blood (Cavity) and no ethanol was detected in the urine. The report listed the following drug being detected: - Tetrahydrocannabinol (Marihuana) detected in the blood (Heart) - 0.005 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana) detected in Urine - 0.0015 (ug/ml, ug/g) Tetrahydrocannabinol Carboxylic Acid (Marihuana) detected in Blood (Heart) According to the FAA Aerospace Medical Research website, Tetrahydrocannabinol (THC) is the psychoactive compound found in marijuana and has effects at levels as low as 0.001 ug/ml. THC has mood altering effects causing euphoria, relaxed inhibitions, sense of well-being, disorientation, image distortion, and psychosis. The ability to concentrate and maintain attention are decreased during marijuana use. Tetrahydrocannabinol carboxylic acid is the inactive metabolite of tetrahydrocannabinol. ADDITIONAL INFORMATION A fuel receipt was located revealing that the airplane had been fueled at HWV, at 1837 on the day of the accident, with 53 gallons of fuel. The Airplane Flying Handbook (FAA-H-8083-3A) Chapter 15, which states in part, "…once the stall has developed and a large amount of lift has been lost, the airplane will begin to sink rapidly and this will be accompanied by a corresponding rapid increase in angle of attack. This is the beginning of what is termed a deep stall. As an airplane enters a deep stall, increasing drag reduces forward speed to well below normal stall speed. The sink rate may increase to many thousands of feet per minute. The airplane eventually stabilizes in a vertical descent…it must be emphasized that this situation can occur without an excessively nose-high pitch attitude…Deep stalls are virtually unrecoverable." Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25A) Section 4 "Aerodynamics of Flight" states "The CG range is very important when it comes to stall recovery characteristics. If an aircraft is allowed to be operated outside of the CG, the pilot may have difficulty recovering from a stall. The most critical CG violation would occur when operating with a CG which exceeds the rear limit. In this situation, a pilot may not be able to generate sufficient force with the elevator to counteract the excess weight aft of the CG. With the ability to decrease the AOA [angle of attack], the aircraft continues in a stalled condition until it contacts the ground." The section further goes on and states the following: "Longitudinal stability is the quality that makes an aircraft stable about its lateral axis. It involves the pitching motion as the aircraft's nose moves up and down in flight. A longitudinally unstable aircraft has a tendency to dive or climb progressively into a very steep dive or climb, or even a stall. Thus, an aircraft with longitudinal instability becomes difficult and sometimes dangerous to fly. Static longitudinal stability or instability in an aircraft, is dependent upon three factors: 1. Location of the wing with respect to the CG 2. Location of the horizontal tail surfaces with respect to the CG 3. Area or size of the tail surfaces" The "Glossary" defines CG as "the point at which an airplane would balance if it were possible to suspend it at that point. It is the mass center of the airplane, or the theoretical point at which the entire weight of the airplane is assume to be concentrated. It may expressed in inches from the reference datum, or in percentage of mean aerodynamic chord (MAC). The location depends on the distribution of weight in the airplane." Deep Stall According to a book titled "The Light Airplane Pilot's Guide to Stall/Spin Awareness" a deep stall is "…when the horizontal tail of a conventional airplane becomes buried in the main wing's tail wake and loses its power to push the nose down, or with a canard design when the main wing stalls before the canard does. In both cases, the airplane seeks a higher angle of attack, usually above 40 degrees, and stabilizes there. There may not be enough elevator authority to reduce the angle of attack for recovery." According to Advisory Circular AC90-109 Section 5c(6) "It's also possible, even for a seemingly carefree handling airplane, to achieve what some have called a deep stall, where there is not sufficient nose-down pitch authority to break the stall, possibly creating an unrecoverable situation. Some airplanes can pitch nose-up before the stall, resulting in a rapid stall entry unless the pilot counters with a conscious forward yoke/stick motion."
The pilot's failure to ensure that the airplane was loaded within its calculated center of gravity limits, which resulted in longitudinal instability and a subsequent unrecoverable stall.
Source: NTSB Aviation Accident Database
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