Danbury, CT, USA
N612DF
CESSNA 172
The private pilot and two passengers were departing in the airplane from the 4,422-ft-long asphalt runway. A witness reported that, while still over the runway, the airplane began to lose altitude, then entered a nose-high attitude. The airplane subsequently entered a left-turning descent consistent with an aerodynamic stall. Examination of the wreckage did not reveal any preimpact mechanical anomalies; although the ignition key was found in the left magneto position, the preimpact position of the key could not be determined. Performance calculations revealed that the airplane should have used less than half the available runway distance to clear a 50-ft obstacle at maximum gross weight with flaps extended to 10°. Weight and balance calculations revealed that the airplane was operating about 59 lbs over its maximum allowable gross weight at the time of the accident, and the flaps were found in the retracted position. It is likely that the pilot noticed the airplane's degraded climb performance after takeoff and attempted to compensate by increasing the airplane's pitch attitude, which resulted in decaying airspeed, an exceedance of the critical angle of attack, and an aerodynamic stall.
On July 30, 2017, about 1025 eastern daylight time, a Cessna 172S, N612DF, was substantially damaged when it impacted terrain shortly after takeoff from Danbury Municipal Airport (DXR), Danbury, Connecticut. The pilot died from his injuries 4 days after the accident, and the two passengers received serious injuries. The airplane was owned by a private company and was being operated by Arrow Aviation LLC as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, which was originating at the time of the accident.The rear-seat passenger was a certificated pilot with about 1,500 hours of flight experience. He stated that, when the airplane was cleared for takeoff, the pilot taxied to the runway and applied what sounded like full engine power. The rear-seat passenger could not see the instruments or flight controls from where he was seated. After a short ground roll, the airplane took off, but from what he could see out the side window, it seemed that the airplane was not gaining altitude normally. Less than 1 minute later, the pilot stated, "we're going in." According to an air traffic controller at DXR, the airplane lost altitude after takeoff while still over runway 26, a 4,422-ft-long runway. He then observed it "appearing to correct" as it had assumed a more nose-up attitude. It then began a left roll, followed by a "full nose up attitude, rolling to the left," before it descended and impacted the ground. Another witness, who was in a dog park near the accident site, stated that he heard a small airplane "lumbering" and sounding under-powered. He saw the airplane appear to turn sharply 180°, then impact the ground. According to Federal Aviation Administration records, the pilot held a private pilot certificate with ratings for airplane single-engine land and rotorcraft-helicopter. His most recent FAA third-class medical certificate was issued June 14, 2016, at which time he reported 582 hours of total flight experience. The pilot's logbook was not recovered. Review of the airplane's maintenance records revealed that the most recent annual inspection was completed on July 21, 2017, about 17 flight hours before the accident. At that time, the airframe had accrued about 4,013 hours and the engine had accrued 656 hours since overhaul. According to fuel records and statements from the operator, the airplane was fueled to capacity on the afternoon of July 28. The accident flight was the first flight since that fueling. The airplane's maximum gross weight was 2,550 lbs. The airplane's estimated weight at the time of the accident, including full fuel and the three occupants (not accounting for any baggage), was about 2,609 lbs. Review of takeoff performance data revealed that, at 2,550 lbs, a pressure altitude of 500 ft mean sea level, and a temperature of 20°C, the airplane required about 1,770 ft to clear a 50-ft obstacle. The data assumed no wind and flaps extended 10°. At 1053, the reported weather at DXR included wind from 350° at 9 knots, the temperature was 23°C, and the dew point was 12°C. An initial examination of the airplane by a Federal Aviation Administrator (FAA) inspector revealed that the fuselage came to rest upright in a nose-down attitude in an area of heavy brush about 1,000 ft from the departure end of the runway. The left wing was partially separated from the fuselage and exhibited leading edge crush damage from the root to the tip. The outboard one-third of the right wing was bent upward and aft. The fuselage was buckled on both sides aft of the rear window, and the left rear pillar was crushed and separated from the roof. The nose section, including the engine, was crushed and displaced upward and aft. The empennage, vertical and horizontal stabilizers, rudder, and elevators were largely undamaged. The ignition key was found positioned to the left magneto; however, the preimpact position of the key could not be determined. Several branches were found severed at a 45° angle in the westerly path leading up to the airplane consistent with propeller contact. Both propeller blades exhibited leading edge gouges and chordwise scratches. Fuel samples from both tanks were blue in color and absent of water. Oil was present in the engine, but the quantity could not be determined due to the resting position of the engine. The wreckage was transported to a recovery facility and examined again. Flight control continuity was confirmed from all control surfaces to the cockpit area. Measurement of the elevator trim jackscrew corresponded to a 5° tab up (nose down) elevator trim. Measurement of the flap actuator revealed that the flaps were in the fully retracted position. The engine crankshaft was rotated by means of a tool inserted in the vacuum pump drive pad and continuity of the crankshaft to the rear gears and to the valve train was observed. The interiors of the cylinders were examined with a lighted borescope and no anomalies were noted. The fuel servo, engine-driven fuel pump, flow divider, and injector nozzles remained attached to the engine and were removed and partially disassembled. The fuel servo regulator section was partially disassembled and no damage was noted to the rubber diaphragms or other internal components. The fuel servo fuel inlet screen was absent of debris. The flow divider was partially disassembled. No debris was noted inside and no damage to the rubber diaphragm was noted. The two-piece fuel injector nozzles were unobstructed. The engine-driven fuel pump was partially disassembled and no damage was noted to the rubber diaphragms or the internal check valves. Liquid with an odor consistent with aviation gasoline was observed in the engine-driven fuel pump, the hose from the pump to the servo, in the servo and in the hose from the servo to the flow divider. Both magnetos were removed and produced spark from all electrode towers when rotated by hand. A GPS data card, and three personal electronic devices were forwarded to the National Transportation Safety Board Vehicle Recorder Laboratory, Washington, DC. No performance data were recovered for the accident takeoff. According to the Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B) Chapter 10, Weight and Balance, excessive weight reduces flight performance in almost every respect. Some of the most important performance deficiencies of an overloaded aircraft include higher takeoff speed, longer takeoff run, reduced rate and angle of climb, and higher stalling speed.
The pilot's exceedance of the airplane's critical angle of attack during initial climb, which resulted in an aerodynamic stall. Contributing to the accident was the pilot's decision to operate the airplane above its maximum gross weight, which likely reduced its takeoff performance.
Source: NTSB Aviation Accident Database
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