Newborn, GA, USA
N1612F
Cessna 172
The pilot, who was also the owner of the airplane, departed the airport, likely to look at property about 240 nautical miles away. Radar track data showed a target correlated to be the accident airplane after its departure. About 1 hour into the flight, the airplane turned west southwest in a meandering track for about 10 miles, then it made a right turn to the north and completed several left 360° turns, before turning back to the east and completing two additional right 360° turns. The airplane proceeded to the north briefly, completing several 360° turns before continuing into 13 360° right turns that progressed in an easterly direction until radar contact was lost near the accident site. Two witnesses observed the airplane flying low just before the accident, and another witness stated that it was circling and then descended below the tree line. Postaccident examination of the airframe and engine revealed no preimpact mechanical anomalies that would have precluded normal operation. However, examination of the muffler assemblies revealed that the right muffler exhibited cracks and through-thickness metal wastage. Fractures associated with the separation of the aft face with inlet tube exhibited largely oxidized fracture surfaces and thinned walls. The center inlet tube was separated from the rest of the muffler due to loss of mechanical integrity from metal wastage. Holes and wall thickness loss were also noted around the muffler body, which likely led to an escape of exhaust gasses and associated carbon monoxide entering the cabin during the flight. Toxicology testing performed postaccident identified 48 to 61% carboxyhemoglobin in cavity blood. Levels of carbon monoxide of 40% and above lead to confusion, seizures, loss of consciousness, and death. Although there was a postcrash fire, the pilot sustained severe impact-related injuries and would not have been breathing after impact. While postaccident toxicological testing also detected the presence of potentially impairing medications, it is most likely that the pilot experienced carbon monoxide poisoning during the flight when carbon monoxide entered the cabin from the degraded right muffler. The carbon monoxide poisoning led to the pilot’s impairment/incapacitation and his inability to control the airplane, as demonstrated in the airplane’s erratic flightpath during the flight. The pilot’s underlying cardiac disease would have increased his susceptibility to the effects of the carbon monoxide poisoning. According to the airplane’s maintenance records, the left muffler was replaced about 10 years before the accident; however, there was no documentation that showed installation of, or maintenance performed to, the right muffler. At the time of the accident, the airplane was overdue for an annual inspection. Had the pilot had the airplane inspected, it is possible that the deteriorated condition of the right muffler might have been detected and corrected.
HISTORY OF FLIGHTOn January 6, 2020, at 1423 eastern standard time, a Cessna 172H, N1612F, was destroyed when it was involved in an accident near Newborn, Georgia. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot, who owned the airplane, departed Toccoa Airport-RG Letourneau Field (TOC), Toccoa, Georgia, about 1230 and was destined for Cairo-Grady County Airport (70J), Cairo, Georgia, about 240 nautical miles away. The pilot’s daughter stated that he was likely flying to Cairo to look for property in the area. Radar track data provided by the Federal Aviation Administration (FAA) showed a target correlated to be the accident airplane after departure from TOC. The airplane proceeded on a heading of about 170° for 15 miles, taking a right turn to about 233° for 5 miles, then turning south again to 190° for an additional 25 miles. About 1 hour into the flight, the airplane turned west-southwest (figure 1) in a meandering track for about 10 miles in the vicinity of Newborn; it then made a right turn to the north and completed several left 360° turns before turning back to the east and completing two additional right 360° turns. The airplane proceeded to the north briefly, completing several 360° turns before continuing into 13 360° right turns that progressed in an easterly direction until radar contact was lost near the accident site (figure 2). The pilot’s daughter stated that she thought there was no reason why the pilot would be looking at property in Newborn from the air. Two witnesses observed the airplane flying low just before the accident, and another witness stated that the airplane was circling and then descended below the tree line. The airplane impacted terrain, and a postaccident fire ensued. Figure 1 - Overview of final route of flight. Figure 2 - Final flight track through loss of radar near accident site. PERSONNEL INFORMATIONAccording to FAA airmen records, the pilot, age 72, held a private pilot certificate with a rating for airplane single-engine land. The pilot reported 344 hours total flight time as of his most recent aviation medical exam on November 15, 2013. The pilot’s last entry in his logbook was on July 16, 2019; his total flight time was 358.65, of which 1/4 hour was during the previous 6 months. AIRCRAFT INFORMATIONThe airplane’s most-recent annual inspection was completed on September 17, 2018. Only three other records of maintenance were found for the 10 years before the accident: two annual inspections on May 27, 2013, and November 18, 2010, and replacement of the left muffler on April 1, 2010. There was no documentation in the records that showed installation of, or maintenance performed to, the right muffler. The airplane had been operated about 93 hours over that period. The mechanic who conducted the 2013 annual inspection and almost all of the airplane’s maintenance from 2008 to 2013 knew the airplane well and considered the pilot a friend; he stated that the airplane was in “rough shape.” Within the last few years, the pilot had asked him to conduct maintenance on the airplane; there were issues with the electrical system and a flap. The mechanic stated he didn’t want to “touch” the airplane unless the pilot agreed to a comprehensive annual inspection. The pilot declined and elected to take it to another mechanic. AIRPORT INFORMATIONThe airplane’s most-recent annual inspection was completed on September 17, 2018. Only three other records of maintenance were found for the 10 years before the accident: two annual inspections on May 27, 2013, and November 18, 2010, and replacement of the left muffler on April 1, 2010. There was no documentation in the records that showed installation of, or maintenance performed to, the right muffler. The airplane had been operated about 93 hours over that period. The mechanic who conducted the 2013 annual inspection and almost all of the airplane’s maintenance from 2008 to 2013 knew the airplane well and considered the pilot a friend; he stated that the airplane was in “rough shape.” Within the last few years, the pilot had asked him to conduct maintenance on the airplane; there were issues with the electrical system and a flap. The mechanic stated he didn’t want to “touch” the airplane unless the pilot agreed to a comprehensive annual inspection. The pilot declined and elected to take it to another mechanic. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted dense woods and terrain about 3 miles east of Newborn, Georgia. The wreckage path was on a magnetic heading of about 215° and was about 180 ft long. The airplane came to rest inverted. Both wings separated during impact, and the fuselage was consumed by a postimpact fire. All airframe, control surfaces, and engine components were located at the scene, and several smaller pieces of aluminum, plexiglass, wheel fairing, and a door were found along the wreckage path among broken tree limbs and branches. The propeller was found in the engine impact crater and was sheared off the hub during the impact; it exhibited gradual aft bending and had a few diagonal chordwise scrapes on the blades. Flight control cable continuity was confirmed through multiple overload breaks and failures. The left- and right-wing fuel tanks were ruptured and thermally damaged. The left fuel cap was secured in place, and the right fuel cap was melted but remained attached to the chain that was secured in place. The left and right flaps and associated actuators were found in the up (stowed) position. The engine remained largely intact, although there was significant thermal damage on the aft section of the engine near the firewall. The spark plugs were removed and examined. They appeared to have minimal wear when compared to the Champion Check-A-Plug chart and did not display any evidence of carbon or lead fouling that would preclude normal operation. Engine thumb compression and suction on all cylinders were confirmed, and crankshaft continuity was confirmed from the front to the accessory gear section of the engine through a full 720° of rotation. The engine examination did not reveal any preimpact anomalies that would preclude normal operation. The left and right mufflers, and their respective shrouds, had separated during the accident sequence and were found partially buried in mud, protected from the postaccident fire. They were sent to the National Transportation Safety Board (NTSB) Materials Laboratory for a detailed examination. The left smooth muffler exterior surface was sound with no evidence of cracks or through-thickness metal wastage. The right muffler and shroud exhibited substantial mechanical damage. The aft face of the muffler with inlet tube was separated from the assembly and was not recovered. The right smooth muffler surface exhibited cracks and through-thickness metal wastage. The fractures associated with the separation of the aft face with inlet tube exhibited largely oxidized fracture surfaces and thinned walls. The center inlet tube was separated from the rest of the muffler due to loss of mechanical integrity from metal wastage. Holes and wall thickness loss were also noted around the muffler body. A metallurgical cross-section taken through an exemplar area of metal wastage showed evidence of general thermal oxidative loss of material wall thickness as well as through-thickness holes and cracks. There were metal wastage and wall-thickness though-holes adjacent to the crimp seal between the muffler tube and the forward end plate as well. Due to the extensive postaccident fire damage to the fuselage, the NTSB was unable to determine if the airplane was equipped with any type of carbon monoxide detection equipment. MEDICAL AND PATHOLOGICAL INFORMATIONAccording to the autopsy performed by the Division of Forensic Sciences, Georgia Bureau of Investigation, the cause of death was multiple blunt force injuries and carbon monoxide toxicity. In addition, moderate atherosclerotic stenosis (70%) of the left anterior descending coronary artery and mild atherosclerotic stenosis (30%) of right coronary artery were identified. Toxicology testing performed by the Division of Forensic Sciences, Georgia Bureau of Investigation, identified 61% carboxyhemoglobin in cavity blood. Additional toxicology testing performed by the FAA’s Forensic Science Laboratory identified 48% carboxyhemoglobin in cavity blood as well as bupropion (a potentially sedating antidepressant) and one of its metabolites, citalopram (generally considered a nonsedating antidepressant) and one of its metabolites, trace amount of diphenhydramine (a sedating antihistamine), diltiazem (a blood pressure medication), atorvastatin (a cholesterol-lowering drug), sildenafil (used to treat erectile dysfunction) and one of its metabolites, and a metabolite of aspirin in the pilot’s blood and/or tissues. Medical Records Personal medical records were obtained from the pilot’s primary care doctor. These records were limited to a single visit to obtain bloodwork before a cardiac catherization; they did not contain a medical history or list of medications. The bloodwork was unrevealing. A copy of the cardiology record was included. The cardiology record from a visit dated October 21, 2019, documented that the pilot had known coronary artery disease, paroxysmal atrial fibrillation, a previous stroke, high blood pressure, arthritis, and carotid artery disease. At the time, his daily medications included diltiazem, lisinopril (another blood pressure medication), omeprazole, atorvastatin, sildenafil, citalopram, lorazepam (a sedating benzodiazepine), and Eliquis (a blood thinner). He had undergone a cardiac catheterization on July 25, 2019, which demonstrated severe calcific diffuse coronary artery disease that was not amenable to procedural intervention. At the time of the pilot’s last FAA medical examination in 2013, he had reported having high blood pressure and the use of medication to treat it. The pilot had allowed his aviation medical certificate to expire and had not reported his medical history or recent use of medications to the FAA. Carboxyhemoglobin Carbon monoxide (CO) is an odorless, tasteless, colorless, nonirritating gas formed by hydrocarbon combustion. CO binds to hemoglobin with much greater affinity than oxygen, forming carboxyhemoglobin; elevated levels result in impaired oxygen transport and utilization. Nonsmokers may normally have up to 3% carboxyhemoglobin in their blood; heavy smokers may have levels of 10 to 15%. Acutely, low levels of CO may cause vague symptoms like headache and nausea, but increasing levels (40% and above) lead to confusion, seizures, loss of consciousness, and death.
The pilot’s impairment/incapacitation from carbon monoxide poisoning due to a degraded muffler. Contributing to the accident was the pilot’s failure to properly maintain the airplane.
Source: NTSB Aviation Accident Database
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