ERA19FA164

A partial loss of engine power due to a stuck exhaust valve and the flight instructor's exceedance of the airplane's critical angle of attack following the loss of power, which resulted in an aerodynamic stall at low altitude.

The flight instructor and student pilot were conducting simulated engine-out emergency procedures in the airport traffic pattern. About 300-400 ft above ground level after takeoff, witnesses reported that the flight instructor announced on the radio that the engine had quit. Witnesses reported that the airplane then entered a nose-high, steep left turn before pitching down and impacting the ground. Postaccident examination of the airframe and flight controls revealed no mechanical anomalies that would have precluded normal operation. Examination of the engine revealed that the No. 4 cylinder exhaust valve was stuck in the valve guide due to excessive combustion deposits. It is likely that the stuck exhaust valve resulted in a partial loss of engine power. A flight instructor who flew the accident airplane the day before the accident flight reported experiencing engine roughness when performing simulated engine-out procedures. Following that flight, a mechanic cleaned the sparkplugs, performed an engine run-up, and returned the airplane to service; however, maintenance records did not show that the engine valves were inspected for sticking at that time. Manufacturer service instructions suggested inspecting for valve sticking at regular intervals or sooner if sticking was suspected. If a valve inspection had been completed in accordance with engine manufacturer guidance the day before the accident following the report of engine roughness, it is likely that the heavy carbon deposits on the exhaust valve would have been detected. Given that the flight instructor reportedly had students trim the airplane nose-up when landing, it is possible that the airplane was trimmed nose-high at the time of takeoff and the subsequent loss of engine power. Such a trim setting would have led to excessive pitch up, resulting in a rapid loss of airspeed, an exceedance of the airplane's critical angle of attack, and an aerodynamic stall at low altitude.

The 1255 recorded weather observation at Sonny Callahan Airport, Fairhope, Alabama, about 8 miles west of the accident location, included wind from 270° at 3 knots, 10 miles visibility, clear skies, temperature 26°C, dew point 17°C, and an altimeter setting of 30.03 inches of mercury. The flight instructor held a commercial pilot certificate with ratings for airplane single- and multi-engine land and instrument airplane. She also held a flight instructor certificate with a rating for airplane single-engine. Her most recent Federal Aviation Administration (FAA) first-class medical certificate was issued February 14, 2019. An examination of the flight instructor's logbook revealed 977.5 total hours of flight experience, of which 507.2 hours were in the accident airplane make and model. Her most recent flight review was completed February 27, 2019, and she had logged about 340 hours of instruction in the previous 90 days. A review of the student pilot's logbook revealed that he had accumulated about 16 hours of total flight experience in the previous 3 years, all of which were in the accident airplane make and model. The student pilot had not yet flown solo and no flights were logged in the preceding year. According to FAA airworthiness records, the four-seat, low-wing, tricycle gear airplane was manufactured in 1969. It was powered by a Lycoming O-320-D3G, 140-horsepower engine which drove a metal, two-bladed, fixed-pitch Sensenich propeller. According to airplane maintenance logbooks, an annual inspection was completed on March 12, 2019, at a tachometer time of 6,891.92 hours. The tachometer located in the airplane at the time of the accident indicated 6,985.78 hours, which was 93.86 hours since the annual inspection and 1,976.42 hours since the engine's most recent major overhaul. Student Pilot The Deputy Chief Medical Examiner of the Alabama Department of Forensic Sciences, Mobile, Alabama, performed an autopsy of the student pilot. The cause of death was determined to be from blunt force injuries. Toxicology testing yielded negative findings for ethanol and tested-for drugs. Flight Instructor The FAA's Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, performed toxicology testing on submitted specimens from the flight instructor. The test results yielded negative findings for ethanol and tested-for drugs. Examination of the accident site and wreckage revealed several impression marks on the ground along a 243° heading. The airplane came to rest upright on the edge of airport property. All major airplane components were located at the site. The left wing was separated from the fuselage at the wing root and came to rest inverted 18 ft from the main wreckage. The empennage was crushed and folded inverted along the left side of the passenger cabin. The vertical stabilizer was attached and bent 90° to the right at the attachment points. The rudder remained attached and was bent and impact damaged along its entire length. The outboard 3 ft of the right stabilator was impact crushed and the left side of the stabilator and trim tab was undamaged. The top of the fuselage aft of the front seats was folded back on top of the aft cabin. The forward end of the fuselage, including the instrument panel, forward cabin door, firewall, and engine, were folded down and under the forward cabin floor. The engine remained attached to the mount. The propeller was separated from the crankshaft propeller flange. The left aileron bellcrank, which remained attached to the aileron and balance cables, was located with the fuselage and had been pulled from its mounting and separated from the wing. Control cable continuity was confirmed from the cockpit to each of the control surfaces except the left aileron, which was continuous to the aileron bellcrank. The left wing, including the attached flap and aileron, was impact fractured and damaged on all surfaces. The fuel tank was breached, and the grass around the wing displayed fuel blighting. The landing gear was fractured off and connected by the brake hose. The right wing, including the attached flap and aileron, was crushed from the wingtip to mid-wing and displaced upward with multiple fractures. The outer 2 ft of the flap was crushed in a negative direction, and the inboard 2 ft of aileron was impact fractured, bent, and crushed. The landing gear remained attached. The fuel filler cap remained installed in the filler opening, and fuel was observed in the fuel tank when the cap was removed. The left cockpit seat was separated from its seat rails and from the fuselage. The lap belt was buckled. The outboard end of the lap belt remained attached to its mounting bracket, which was separated from the fuselage. The right cockpit seat remained attached to its seat rails. The lap belt was unbuckled. The airplane was not equipped with shoulder harnesses. Examination of the airframe revealed no preimpact failures of any flight control surface or flight control system components. The engine and its accessories were examined. The top spark plugs were removed, and visual examination revealed no anomalies. The rocker box covers were removed, and no anomalies were noted with the valve springs and rocker arms. Manual rotation of the engine's crankshaft produced compression on all four cylinders. The left and right magnetos were removed, and sparks were observed on all towers when each magneto was rotated by hand. Examination of the cylinders with a lighted borescope revealed a circular impact mark consistent with an exhaust valve strike on the No. 4 piston. The No. 4 cylinder was removed from the crankcase. The rocker arm, valve keepers, and springs were removed. The exhaust valve could not be removed from the valve guide by hand and was removed utilizing a hammer and a drift. The exhaust valve exhibited combustion deposits on the stem close to the rear of the valve face. Carbon build-up was observed in the valve guide. The engine-driven fuel pump was removed from the engine and actuated by hand. Bubbles were observed around the gasket when the pump arm was actuated. Four screws on the periphery of the pump were found to be loose. Examination of the propeller blades revealed that one blade was bent forward about mid-span. The blade exhibited leading edge polishing and spanwise scratches on the forward face. The other blade was bent aft about mid-span with twisting towards low pitch. The outer portion of the blade exhibited leading edge polishing and chordwise scratches. On May 6, 2019, at 1247 central daylight time, a Piper PA-28-140, N5542U, was destroyed when it impacted terrain shortly after takeoff from Foley Municipal Airport (5R4), Foley, Alabama. The flight instructor was seriously injured, and the student pilot was fatally injured. The airplane was owned and operated by Lightning Aviation as a Title 14 Code of Federal Regulations (CFR) Part 91 instructional flight. Visual meteorological conditions prevailed in the area, and no flight plan was filed for the local flight. According to a witness, who was a flight paramedic on another instructional flight at 5R4, he saw the accident airplane take off from runway 36 after a touch-and-go landing. He then heard the flight instructor announce on the radio, "My engine just quit." He saw the accident airplane pitch up "like a power-on stall" then "lean to the left to start a spin" about 300-400 ft above ground level (agl). He added that it was only about 3 seconds from the time he saw the airplane in a nose-high pitch attitude to when it was descending toward the ground. A flight instructor who was entering the traffic pattern at 5R4 reported that the airplane seemed to be making an aggressive left turn as if returning to the airport. According to another flight instructor who flew the airplane the morning of the accident, the airplane "didn't seem to climb very well," which he attributed to high density altitude. He stated