San Antonio, TX, USA
N6678P
Piper PA24
While en route to the destination, the pilot reported to air traffic control that he had an “engine failure” and declared an emergency. The pilot was cleared to land at another airport and responded that he would be “circling above” the airport before landing. Flight track data revealed that the airplane procced away from the runway, then descended and turned back inbound. Analysis of ADS-B data revealed that the calibrated airspeed decreased below the airplane published stall speed of 56 knots. The tower controller and a ground witness observed the airplane in a steep nose down attitude and spiral into the ground. Surveillance video also captured the airplane in a steep descent and counterclockwise spiral before it impacted terrain. The airplane sustained substantial damage to both wings, the empennage, and the fuselage. Examination of the airplane and engine did not reveal any preimpact mechanical malfunctions or anomalies that would have precluded normal operation. Chordwise scratches were detected on 2 of the 3 propellers blades, which indicates that the engine was likely producing some power at the time of impact. It could not be determined what kind of engine malfunction the pilot experienced. It also could not be determined if the pilot intended to continue the approach to the runway or to land on a nearby street. The circumstances of the accident are consistent with the loss of engine power reported by the pilot for undetermined reasons because an examination of the engine did not reveal any preimpact malfunctions. The pilot subsequently allowed the airspeed to decrease below stall speed while maneuvering to land, which resulted in an inadvertent stall/spin on approach with insufficient altitude to recover.
HISTORY OF FLIGHTOn December 1, 2019, about 1825 central standard time, a Piper PA24-250 airplane, N6678P, was substantially damaged when it was involved in an accident near the San Antonio International Airport (KSAT), San Antonio, Texas. The private pilot, flight instructor, and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight was conducted under a visual flight rules flight plan, at night, with flight following. The airplane departed Sugar Land Regional Airport (SGR), Houston, Texas, about 1716 with the intended destination of Grier Airport (71TX), Boerne, Texas. Paperwork found in the airplane showed that the pilot was training for an airplane instrument rating, although it is unknown if training was being conducted before the accident, or if the training was to begin at 71TX. While in cruise flight, the pilot reported to San Antonio Approach Control that the airplane experienced an “engine failure” and declared an emergency. The pilot initially accepted clearance to circle for runway 04 at SAT and was then cleared to circle “at his discretion.” The pilot reported that he had the airport in sight and was cleared to land on runway 13R. The pilot responded that they were “circling above” and would land on runway 13R. During the approach, a brief radio transmission with the sound of someone distressed was heard on tower’s radio frequency and the tower controller witnessed the airplane in a spiraling descent. A witness on the ground described seeing the airplane turn to the east and then the airplane went “nose down” towards the ground. A review of Automatic Dependent Surveillance-Broadcast (ADS-B) data captured the airplane’s path as it approached the San Antonio area. The data were analyzed, and knots calibrated airspeed (KCAS) was derived for this description of the flight. The flight path was headed toward OWEKY, an approach fix for the RNAV 35 approach to Boerne Stage Field (5C1), until about 1822 when the airplane began to maneuver to land on runway 13R at SAT. The airplane flew to the southwest and descended to about 2,900 ft mean sea level (MSL) when the airplane rolled out toward the approach end of 13R. At this point, the airplane was about 2,000 ft above the touchdown zone elevation of the runway, about 0.48 nautical miles from the runway threshold, and 1,200 ft right of runway centerline. The pilot continued a descending left turn and flew away from runway 13R for about 0.6 nautical miles and descended to 2,000 ft MSL. At 1825:13, the airplane began a left turn for runway 13R at an airspeed of 66 KCAS. Halfway through the turn, the airplane’s airspeed was 76 KCAS, and the descent rate increased to about 1,200 ft per minute (fpm). As the airplane was almost 180° through the turn back to runway 13R, the descent rate increased to over 6,000 fpm and the airspeed increased to 93 KCAS before the airspeed began to decay. At 1825:29 the airplane tracked southeast towards the runway, generally along Rhapsody Drive. At 1825:30.7, the airplane slowed below the published stall speed of 56 knots with the last point about 50 KCAS. According to the airplane flight manual, the published stall speed for landing gear and flaps up is 62 knots. The published stall speed with the landing gear and flaps extended is 56 knots. A surveillance camera captured the airplane’s impact with terrain. The camera was oriented south and was focused on a parking lot and Rhapsody Drive. The first indication of the accident airplane was the landing lights which illuminated the ground and rotated in a counterclockwise circle. The lights made about one full rotation before the airplane entered the field of view. The airplane was pointed about 70° nose down. The top of the airplane pointed toward the camera as it rapidly descended and the airplane was in a counterclockwise spiral as it impacted terrain. PERSONNEL INFORMATIONThe private pilot owned the accident airplane. His logbook number “2” was recovered at the accident site. It revealed that the pilot received his private pilot endorsement on October 3, 2014. He flew often and received instrument flight training from the accident flight instructor. It is unknown if instrument training was being conducted on the accident flight. The pilot had accumulated at least 151.4 hours in the accident airplane and about 404.9 total hours. A record of his most recent flight review was not located in the available logbook. The flight instructor’s logbook was not made available for the investigation. She held a current Federal Aviation Administration (FAA) BasicMed certificate dated March 8, 2018. On a previous medical application dated May 12, 2016, she reported having accrued over 2,150 total hours. It could not be determined if the flight instructor was acting as an instructor during this flight or was a pilot-rated-passenger. AIRCRAFT INFORMATIONA review of engine maintenance logbook entries found the most recent work occurred on November 14, 2019, which consisted of an oil change and new oil filter installed on the airplane. The mechanic noted that no foreign debris was detected in the previous filter. An operational check of the engine was recorded with “no leaks found.” At the time of the work, the engine had 4,686.4 total hours and 555.3 hours since major overhaul. Before that, on April 17, 2019, an annual inspection was completed on the engine, no discrepancies were identified during that inspection. A fuel receipt was located in the wreckage which showed that the airplane was fueled with 33 gallons of 100 low lead aviation fuel at David Wayne Hooks Memorial Airport on the morning of the accident. AIRPORT INFORMATIONA review of engine maintenance logbook entries found the most recent work occurred on November 14, 2019, which consisted of an oil change and new oil filter installed on the airplane. The mechanic noted that no foreign debris was detected in the previous filter. An operational check of the engine was recorded with “no leaks found.” At the time of the work, the engine had 4,686.4 total hours and 555.3 hours since major overhaul. Before that, on April 17, 2019, an annual inspection was completed on the engine, no discrepancies were identified during that inspection. A fuel receipt was located in the wreckage which showed that the airplane was fueled with 33 gallons of 100 low lead aviation fuel at David Wayne Hooks Memorial Airport on the morning of the accident. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted in a nose low attitude in an empty parking lot. A small crater in the asphalt was the initial impact point and the wreckage was found about 10 ft from the crater. All major airplane components were located at the accident scene. Flight control continuity was established from the cockpit controls to the flight control surfaces. Flap position could not be determined. The landing gear switch was in the down position and bent downwards. All fuel screens were clear of debris. The left wing’s fuel filler access door was opened, and an orange microfiber towel was found wedged between the access door and the filler cap. The cap was found to be loose and could be removed without loosening the rubber stopper. The lift detector was impacted damaged and testing of the vane could not be accomplished; however, electrical continuity was confirmed with an ohmmeter. The stabilizer trim jackscrew was found in a setting consistent with partial nose-up trim. Examination of the engine revealed that the crankshaft was fractured, so it was further examined by the National Transportation Safety Board Materials Laboratory. The fracture surface was consistent with overstress and there was no evidence of preexisting damage. The remainder of the engine did not display any anomalies which would have precluded normal operation. The metal, 3-bladed Hartzell propeller remained attached to the engine and was examined. The blades were labelled A, B, and C for documentation purposed. Blade A exhibited chordwise scratches along the cambered side and aft bending and twisting of the outer portion. Blade B exhibited a few chordwise scratches along the cambered side. Blade C was bent aft beginning about 12” from the hub but was relatively undamaged. MEDICAL AND PATHOLOGICAL INFORMATIONAn autopsy was conducted on the private pilot by the Bexar County Medical Examiner’s Office. The autopsy ruled the cause of death was a result of blunt force injuries. Toxicology testing performed by the FAA’s Forensic Services Laboratory identified no evidence of impairing drugs. An autopsy was conducted on the flight instructor by the Bexar County Medical Examiner’s Office. The autopsy ruled the cause of dead was a result of blunt force injuries. Toxicology testing performed by the FAA’s Forensic Services Laboratory identified the presence of ethanol in the liver (12 mg/dL) but not in muscle, as well as the presence of amlodipine and atorvastatin, which had been previously reported to the FAA. Amlodipine is a prescription medication used alone or in combination with other medications to treat high blood pressure. Atorvastatin is a prescription medication used to reduce high cholesterol and triglyceride levels.
The loss of engine power for reason that could not be determined. Contributing to the accident was the pilot’s failure to maintain aircraft control while maneuvering to landing which resulted in an inadvertent stall/spin with insufficient altitude to recover.
Source: NTSB Aviation Accident Database
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