WPR20LA238

The pilot's failure to maintain the airplane’s speed during takeoff near the airplane’s maximum gross weight in high-density altitude conditions, which resulted in the exceedance of the airplane's critical angle of attack and led to an aerodynamic stall, loss of control, and subsequent impact with structures and terrain.

The pilot and five passengers departed on an instrument flight rules cross-country flight. A security camera located about midfield at the airport captured the airplane as it lifted off about 3,700 ft from the beginning of the 5,862-ft runway; the liftoff point was likely due to the effects of a 7- to 10knot tailwind. The airplane then began a series of shallow climbs and descents that continued until the airplane was no longer visible on the camera video. About 1 minute 15 seconds after takeoff, the video captured the airplane again as it descended at a steep angle into a residential neighborhood about 1.5miles southeast of the airport. The airplane struck a tree and three structures before it came to rest on its left side in a backyard of a private residence. A postaccident fire ensued, which consumed most of the wings, the cabin area of the fuselage, and a residence. GPS data revealed that the airplane did not exceed an altitude of 120 ft above ground level. Recorded engine data revealed consistent operation of the engine throughout the flight until about 15 seconds before the loss of data, when the exhaust gas temperatures and the fuel flow fluctuated likely because the pilot was adjusting the mixture lever. No mechanical malfunctions or failures with the airplane were found that would have precluded normal operations. The density altitude about the time of the accident exceeded 7,200 ft mean sea level, and the airplane was close to its maximum gross weight. The effects of high-density altitude conditions and a heavy airplane weight on takeoff performance include increased takeoff roll distance and reduced rate of climb. Review of performance charts indicated that the airplane should have been able to climb at a rate around 500 ft per minute; however, the video evidence indicated that, after takeoff, the airplane had difficulty establishing climb performance. It is likely that, after losing ground effect and while experiencing degraded climb performance due to the high-density altitude, the pilot responded by repeatedly pitching the nose down to gain airspeed and then pitching the nose up to climb. The engine data showed that the pilot apparently manipulated the mixture lever to gain power; however, soon afterward, the airplane’s critical angle of attack was likely exceeded, which resulted in an aerodynamic stall, a loss of control, and an impact with structures and terrain. A debris path of about 95 ft and minor damage to the spinner and front of the engine cowling suggested that the airplane’s descent was not consistent with a fully developed aerodynamic stall. However, multiple witness accounts were consistent with the onset of an aerodynamic stall, including one witness who reported that the airplane started to bank before it “fell from the sky.”

Flight instructors who provided instrument flight training to the pilot stated that he handled the airplane easily and without difficulty. One of the flight instructors stated that he reviewed density altitude and normally aspirated engines with the pilot due to the multiple cross-country flights to Utah that the pilot had previously made. The flight instructor stated that the pilot “didn’t understand why” he continued to bring up pressure altitude and density altitude as discussion topics. The pilot received a high-performance and complex endorsement on December 31, 2019, about 7 months before the accident. The airplane was powered by a 300-horsepower Lycoming O-540-K1G5D, a normally aspirated engine. The engine was equipped with a Hartzell constant-speed propeller. The last annual inspection performed on the airplane occurred on October 18, 2019, at a total time of 451 hours. The airplane engine was last overhauled on December 28, 2012, at a total time of 3,060 hours. Data recovered from an engine data monitor (EDM) revealed engine performance parameters for the accident flight, as shown in figure 2. The data revealed consistent engine operation for the first 10 minutes of operation. About 1337, the exhaust gas temperature (EGT) of all cylinders increased rapidly from about 1,280°F to a maximum of about 1,600°F, and the fuel flow decreased from about 28 to 19 gallons per hour. About 5 seconds later the EGTs for all cylinders decreased to about 1,500°F, and the fuel flow increased to about 22 gallons per hour, consistent with adjustments being made to the mixture control. The EDM data stopped recording about 1338. Figure 2. Engine performance and GPS data from the accident flight. The calculated airplane weight at the time of takeoff was about 3,531 pounds. A weight and balance for the airplane, which was attached to the Pilot’s Operating Handbook (POH) recorded a basic empty weight of 2,257 pounds. The fuel weight equaled 564 pounds. The estimated weights of the pilot and passengers totaled about 690 pounds. On the basis of the items found in the wreckage, 10 pounds of baggage was estimated for the forward storage area, and 10 pounds was also estimated for the baggage in the aft storage area. The calculated weight and balance showed that the center of gravity was 92.84 inches aft of datum. The POH listed the maximum aft center of gravity as 95 inches and the maximum gross weight as 3,600 pounds. According to performance charts for the airplane, for the weight and the environmental conditions at the time of takeoff, the predicted gear-up rate of climb was calculated to be about 500 ft per minute. The stall speed was calculated to be about 65 knots calibrated airspeed with flaps up and 61 knots for flaps 25°. The POH did not provide other flap position data. The airplane first impacted a tree and the edge of a roof on a house. The tree exhibited multiple 45° cuts to branches, consistent with contact from a rotating propeller. The airplane then struck a second house and its detached garage before coming to rest in the backyard of a third house located about 1.5 miles southeast of U42. The debris path extended about 95 ft from the wreckage on a magnetic heading of about 130°. The airplane came to rest on its left side on a magnetic heading of about 170°. All major components of the airplane were found within the main wreckage. Both wings separated from the fuselage at their respective roots and came to rest about 20 ft behind the main wreckage. A postimpact fire consumed the left wing and damaged most of the right wing and the cabin. According to the airplane manufacturer representative, the right flap was observed in the 10°/first-notch position, and the flap torque tube’s right control arm was observed to be at the 1:00 position, which is consistent with that flap setting. Flight control continuity was established from the aileron control cable (attached to the Tbar) to the breaks at the wing root areas of the fuselage. The cable breaks exhibited a splayed, broomstraw appearance. Continuity was also established at the wing roots to the aileron bell cranks and to the aileron of the right wing. The left aileron was consumed by the fire. Elevator control continuity was established from the T-bar to the elevators. Flight control continuity of the rudder was established from the rudder pedals to the rudder. The nose and right main landing gear were retracted. The left main landing gear was consumed by fire. Postaccident examination of the engine revealed that 6 of the 12 spark plugs (4 on the top and 2 on the bottom) had severely worn electrodes. The No. 3 3 cylinder had severely worn electrodes on the top and bottom spark plugs. According to the engine manufacturer, the worn spark plug electrodes were still capable of producing a spark. No mechanical malfunctions or anomalies were observed that would have precluded normal engine operation. On July 25, 2020, about 1338 mountain daylight time, a Piper PA-32-300R, N7677C, was substantially damaged when it was involved in an accident near South Valley Regional Airport (U42), West Jordan, Utah. The pilot, two passengers, and one person on the ground sustained fatal injuries; two passengers sustained serious injuries; and one passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to an employee of the fixed-base operator at the airport, he received a telephone call from a woman who asked to have the airplane “filled up.” The employee also stated that, about 1310 to 1320, the pilot and passengers arrived at the airport and started to load their bags in the airplane. Another employee added 66.8 gallons of 100 low-lead aviation gasoline to the airplane. A security camera located at U42 and oriented to the northeast also captured images of the pilot and passengers as they arrived at the airplane. The video appeared to show the pilot performing a preflight inspection. Afterward the pilot and passengers boarded the airplane, the engine was started, and the airplane taxied onto taxiway B toward runway 16. While the airplane was on the taxiway, the video showed the windsock indicating that the wind was from the north. About 3 minutes later, the airplane was observed during the takeoff roll. A second security camera, located near midfield, showed that the airplane lifted off at 1336:54 and appeared to become airborne abeam taxiway A2, which was about 3,700 ft from the beginning of runway 16. The airplane departed the traffic pattern straight out to the south on a magnetic heading of about 170° and made a series of slight climbs and descents until the airplane was no longer visible on the video. About 1 minute 15 seconds after takeoff (1338:09), the airplane reappeared on the video as it descended at a steep angle into a neighborhood, which was followed by a large plume of black smoke. Downloaded data from the airplane’s onboard GPS unit revealed that the airplane departed U42 about 1336 and traveled southeast on a magnetic heading of 165° for about 1.3 miles and then turned left to a magnetic heading of about 136° for o.2 miles. The airplane climbed to an altitude of 4,720 ft mean sea level (msl)/about 120 ft above ground level (agl) and accelerated to a groundspeed of about 82 knots. The last GPS point, at 1338:24, recorded the airplane near the accident site at an altitude of 4603 ft msl/about 10 ft agl and a groundspeed of about 1 knot, as shown in figure 1. Figure 1. GPS flightpath (magenta line) and the airplane’s direction of travel (blue arrows). Multiple witnesses located near the accident site reported that the airplane’s engine sounded loud, and others observed the airplane at a very low altitude before it descended nose down to the ground. One witness reported that the airplane “started to bank to the east” and “looked like it fell from the sky.” M