ERA13FA259

The flight instructor's inadequate preflight planning and his decision to take off with the airplane at a high gross weight in high temperature conditions that degraded the engine’s available power and his subsequent failure to maintain airspeed while attempting to return to the departure airport, which resulted in the airplane exceeding its critical angle-of-attack and experiencing an aerodynamic stall.

The flight instructor was conducting an introductory flight for the passenger. Witnesses reported observing the airplane lift off about two-thirds down the 4,140-ft-long, asphalt runway and then struggle to gain altitude. The passenger reported that, after takeoff, the flight instructor told him that the engine was not "making power." The flight instructor declared an emergency and was returning to the departure airport when the airplane stalled and impacted the ground about 1/2 mile northwest of the airport. Postaccident examination of the airframe and engine did not reveal any discrepancies that would have precluded normal operation. Weight and balance calculations revealed that the airplane was likely at or above its maximum allowable takeoff weight during the accident flight. Further, the temperature about the time of the accident was about 94 degrees F, and the estimated density altitude at the airport was about 2,200 ft mean sea level. Based on these conditions, if the engine had been operating perfectly, its available power production would have been between about 81 and 85 percent. Therefore, it is likely that these conditions, in combination with the airplane being near or slightly above its maximum allowable weight, reduced the airplane's climb performance and that, while attempting to return to the airport, the pilot failed to maintain adequate airspeed and flew the airplane beyond its critical angle-of-attack, which led to an aerodynamic stall. The flight instructor was ejected from the airplane during the impact after the right seatbelt quick release hook separated from its fuselage anchor. Examination of the quick release hook revealed that it was bent out of the plane of the attachment and twisted. In addition, the hook closure latch was also distorted and deformed. The combined deformations of the hook and latch allowed the hook to disengage. Although it is possible that the deformation occurred during the accident impact, it is more likely that preexisting deformation was present. The airplane had been operated for about 38 hours since its most recent 100-hour/annual inspection, which was performed about 3 weeks before the accident. A condition inspection of the restraint system was required to be performed during this inspection; however, no record was found indicating whether the condition inspection was performed.

Examination of the occupant restraint system performed by an NTSB metallurgist revealed the left seat quick release hook was intact and not deformed. The right seat quick release hook was bent out of the plane of the attachment and twisted. In addition, the hook closure latch was also distorted and deformed. The combined deformations of the hook and latch were such that the spring closure on the latch did not function and the throat of the hook was open, which would allow the hook to engage or disengage on the anchor with the properly installed cotter pin in-place. [Additional information can be found in the Materials Laboratory Factual Report located in the public docket.] A representative from Diamond Aircraft calculated the available engine power during the accident flight based on the airport elevation and the outside air temperature, using flight test data to determine target manifold pressures and the average full power engine RPM. At an RPM of 2,500, and manifold pressures of 27 and 28 inches of mercury, chart brake horsepower was 101.4 (approximately 81 percent power being produced) and 105.9 (approximately 84.7 percent power being produced); respectively. The calculations represented a perfect operating engine and did not take into account engine wear, cylinder compression losses, and fuel system setup conditions. First responders reported that the flight instructor, who was seated in the right seat, was ejected from the airplane. He was located next to the wreckage and was unresponsive. An autopsy was subsequently performed on the flight instructor by the Union County Medical Examiner's Office, Westfield, New Jersey. The autopsy report revealed the cause of death as "blunt impact injuries." Toxicological testing was performed on the pilot by the FAA Bioaeronautical Science Research Laboratory, Oklahoma City, Oklahoma, with no anomalies noted. The reported weather at LDJ, which was at an elevation of 22 feet mean sea level, at 1315, was: wind 220 degrees at 5 knots; visibility 10 statute miles; sky clear, temperature 34 degrees Celsius (C); dew point 16 degrees C; altimeter 30.08 inches of mercury. The estimated density altitude at LDJ at the time of the accident was about 2,200 feet mean sea level. All major portions of the airplane were accounted for at the accident site. The airplane was found upright, with the nose down about 45 degrees. The right wing was displaced aft and folded underneath the fuselage. The empennage was separated about 4 feet forward of the rudder and was resting partially on the ground. Examination of the ailerons, elevator, and rudder control systems did not reveal any preimpact malfunctions. The flap actuator was found in the takeoff position, and the elevator trim actuator was found in the neutral/takeoff position. An undetermined amount of fuel had leaked on the ground and additional fuel was observed leaking from an area around the engine driven fuel pump, which was separated and impact damaged. Fuel samples obtained from the gascolater and fuel tank sump were absent of contamination. The fuel shutoff valve was in the OPEN position. The mixture control linkage was continuous from the engine to the cockpit. The throttle control linkage was connected at the engine; however, the rod end at the cockpit was impact damaged, bent, and broken. The engine sustained significant impact damage and remained attached to the airframe primarily by linkages to the throttle quadrant. The lower front portion of the crankcase was fractured consistent with impact with the ground. All of the cylinders remained attached to the crankcase. The right magneto remained attached. The left magneto was separated and remained attached to the engine via ignition leads. The top spark plugs were removed and exhibited normal operating signatures in accordance with a Champion aviation check-a-plug comparison chart. Their electrodes were intact and dark gray in color. The fuel pump drive coupling was intact and the drive shaft rotated freely when turned by hand. All cylinders were inspected using a lighted borescope. The cylinder bores were free of scoring and no evidence of hard particle passage was observed in the cylinder bore ring travel area. Suction and compression were obtained on all cylinders at the top spark plug holes when the crankshaft was rotated by hand at the crankshaft flange. The propeller hub remained attached to the engine. One propeller blade was fractured at the hub, and the second propeller blade was separated about 2 feet outboard of the hub. Several small propeller blade fragments were observed scattered around the accident site. Subsequent disassembly of the engine, which included bench testing of both magnetos, the fuel pump, throttle body, manifold valve and fuel nozzles did not reveal any anomalies that would have precluded normal engine operation. The left and right seatpans were attached to the aft cockpit bulkhead wall with seven screws (five along the top of the seatpan, and two screws on the bottom forward edge of the seatpan). The left seatpan contained a fracture on the bottom of the pan under a leather insert, a fracture in the middle of the seatpan, and a crushing damage on the inboard edge of the seatpan. The right seatpan contained a fracture along its outboard edge and a section of separated composite material near the inboard forward corner. The left seat restraint system remained intact. The right seat outboard lap belt was found disconnected from its attach point. The quick release hook was distorted and the cotter pin remained installed. [Additional information can be found in the Survival Factors Factual Report located in the public docket.] The complete right seat restraint system and portions of the left seat restraint system were subsequently removed and forwarded to the NTSB Materials Laboratory, Washington, DC for further examination. The two-seat, low-wing, fixed-gear, airplane, serial number C0345, was manufactured in 2005 and primarily constructed of carbon and glass fiber reinforced polymer. It was powered by a Continental Motors Inc. IO-240-B, 125-horsepower engine, equipped with a two-bladed Sensenich wooden propeller. The airplane was certified in the utility category by Transport Canada in accordance with Canadian Airworthiness Manual Chapter 523-VLA. Review of maintenance records revealed that the airplane had been operated for about 1,985 hours since new, and 38 hours since its most recent "100hr/annual" inspection, which was performed on May 10, 2013. At the time of the accident, the engine had been operated for about 2,180 total hours. It was noted that the engine was disassembled, inspected, and repaired for a sudden stoppage during May 2008. According to the airplane flight manual, the airplane's total fuel capacity was 24.5 gallons. According to the owner of the airplane and flight school, the airplane was "topped-off" with fuel the night before and was flown without incident for 2.6 hours prior to the accident. The airplane consumed between 4.5 and 6.0 gallons per hour (gph); however, he noted that consumption was generally "closer to 4.5 gallons" during flight school operations. The owner further reported that performing a weight and balance calculation was part of the preflight checklist and that weight and balance forms for the airplane were available on tables in the flight school; however, flight instructors would normally ask passengers their weight and perform the weight and balance calculation mentally. A weight and balance calculation for the accident flight was performed utilizing an airplane weight and balance form specific to the accident airplane that was available at the flight school. Based on the passenger's reported weight of 290 pounds and the flight instructor's weight during his most recent FAA medical certificate of 235 pounds, the airplane was estimated to be about 30 pounds above its maximum takeoff weight of 1,764 po