N7677CPiper PA-32R-300 · 1975

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.” Multiple witnesses also reported that a house in the neighborhood was on fire.

During a postaccident interview, the wife of the pilot (one of the passengers) stated that he planned an instrument flight rules flight over the Grand Canyon and possibly Lake Powell. The pilot computed the airplane’s weight and balance and showed her the paperwork “where he planned everything out.” She indicated that the pilot was aware of the high temperature and high altitude and that he assured her that “it’s all good.” She could not recall any details of the flight.

Another passenger who survived the accident stated, during a postaccident interview, that everything was “fine” after the takeoff but that, shortly afterward, the airplane “dropped down,” and “the cabin was shaking.” The passenger stated that she heard an “on and off buzzing” sound after liftoff that lasted until the airplane impacted the ground. The passenger also stated that, before the flight, the pilot asked about everyone’s weight and that the bags were weighed to make sure that they were only a few pounds.

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.

At 1355 (17 minutes after the accident), the automated weather for U42 reported the wind as 320° at 7 knots, 300° variable 10 knots, 10 statute miles visibility, clear skies, temperature 32°C, dew point temperature 7°C, barometric pressure 30.06 inches of mercury. Density altitude was calculated to be 7,292 ft msl.

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.

Federal Aviation Administration (FAA) Pamphlet FAA-P-8740-2, Density Altitude, states that “high density altitude corresponds to reduced air density and thus to reduced aircraft performance.” The publication outlines hazards associated with high-density altitude operations and states, in part, the following:

Whether due to high altitude, high temperature, or both, reduced air density (reported in terms of density altitude) adversely affects aerodynamic performance and decreases the engine's horsepower output. Takeoff distance, power available (in normally aspirated engines), and climb rate are all adversely affected....

At power settings of less than 75 percent, or at density altitude above 5,000 feet, it is also essential to lean normally aspirated engines for maximum power on takeoff (unless the aircraft is equipped with an automatic altitude mixture control). Otherwise, the excessively rich mixture is another detriment to overall performance.

According to the FAA’s Airplane Flying Handbook (FAA-H-8083-3C), "under conditions of high-density altitude…the airplane may be able to lift off but will be unable to climb out of ground effect. Consequently, the airplane may not be able to clear obstructions."

The FAA’s Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25B) states, in part, the following:

Due to the reduced drag in ground effect, the aircraft may seem capable of takeoff well below the recommended speed. As the aircraft rises out of ground effect with a deficiency of speed, the greater induced drag may result in marginal initial climb performance. In extreme conditions, such as…high density altitude…a deficiency of airspeed during takeoff may permit the aircraft to become airborne but be incapable of sustaining flight out of ground effect.