History of Flight
On November 30, 2020, at 1213 central standard time, a Piper PA-38-112 airplane, N9879T, was destroyed in an accident near Franklin, Arkansas. The flight instructor and the private pilot receiving instruction were fatally injured. The airplane was operating as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Automatic dependent surveillance-broadcast (ADS-B) data showed that the airplane departed Country Air Estates Airport (1AR9), Lonoke, Arkansas, at 0931, made a short flight to Carlisle Municipal Airport (4M3), Carlisle, Arkansas, arriving at 0946. It remained at 4M3 for about 16 minutes before departing at 1002. The airplane then traveled about 100 nautical miles (nm) north-northwest, turned to a northeast heading, and overflow Marion County Regional Airport (FLP), Flippin, Arkansas, and Baxter County Airport (BPK), Mountain Home, Arkansas, before turning eastbound. It did not land at FLP, and due to a gap in ADS-B data, it could not be determined if it landed at BPK.
After passing BPK, the airplane turned east, contacted Memphis Air Route Traffic Control Center (ARTCC), and obtained an instrument flight rules (IFR) clearance to Walnut Ridge Regional Airport (ARG), Walnut Ridge, Arkansas, about 76 nm east of BPK. During the portion from BPK to ARG, air traffic control initially established radar contact and voice communication. When the airplane was about 60 nm west of ARG, radar contact was lost, and voice communication became intermittent and eventually lost. The final transmissions from the airplane were unclear. The controller attempted to maintain communication using messages relayed through other aircraft and reverted to receiving acknowledgements via microphone key clicks from the accident pilot.
The airplane did not follow a straight-line course between BPK and ARG. It first deviated up to 2.8 nm north of the straight-line course, then turned south and deviated south by as much as 4.5 nm. During the final 5-1/2 minutes of flight, the airplane made 3-3/4 left turns of varying radius, followed by 1-1/4 right turns before the end of recorded ADS-B data. The final ADS-B position was at 1213:36, and the accident site was located about 0.2 nm south-southeast of that position, 4.7 nm south of the straight-line course, and about 35 nm from BPK.
Personnel Information
The flight instructor's flight logbook was not available for review. He reported flight experience including 3,200 total flight hours and 45 hours in the last 6 months as of his last medical exam on October 26, 2020. The logbook for the pilot receiving instruction showed 154.8 total flight hours, including about 98 hours in Piper PA-38 airplanes, as of the last entry on November 28, 2020. His final three logged flights were in the accident airplane: one on November 27, 2020, lasting 2.2 hours, and two on November 28, 2020, lasting 2.2 and 3.0 hours respectively. All three entries noted simulated instrument flight instruction.
Aircraft Information
Maintenance records showed that the airframe and engine received a 100-hour inspection approved on November 20, 2020, by the accident flight instructor, who also held an airframe and powerplant mechanic certificate. A separate annual inspection endorsement was approved by a different mechanic with inspection authorization on the same day. The 100-hour inspection endorsement noted it was completed in accordance with the Piper PA38 Service Manual.
Meteorological Information
Surface temperatures were consistent with the use of cabin heating for the accident flight. AIRMETs for turbulence and icing were in effect at the time. Pilot reports of turbulence ranging from light to occasional severe were reported in the area where the accident occurred.
Wreckage and Impact Information
The airplane impacted trees and terrain. The debris path was about 230 ft long, oriented on a magnetic heading of 320°. The airplane was severely fragmented, with the main wreckage coming to rest about 160 ft from the initial tree impact point. The engine was located about 230 ft from the initial impact point. There was no fire.
Postaccident metallurgical examination of the muffler and cabin heat shroud system revealed multiple branched cracks in the outer shell of one of the two mufflers. The fracture faces were covered with oxidation product, consistent with preexisting cracks before the accident sequence. Metallurgical cross sections showed oxidative degradation that progressed from the inside surface outward.
Other than the cracked muffler, examination by FAA inspectors and a Piper Aircraft investigator revealed no preimpact mechanical malfunctions or anomalies with the airframe or engine that would have precluded normal operation.
Medical and Pathological Information
Toxicology testing on specimens from the flight instructor detected carboxyhemoglobin at 29%. Ethanol was positive at 0.032 gm/hg in muscle tissue but not in liver tissue; n-butanol was also detected in muscle but not liver. Methamphetamine was detected in urine at 307 ng/mL and amphetamine at 31 ng/mL.
Toxicology testing on specimens from the private pilot did not detect carboxyhemoglobin in cavity blood (FAA lab reporting limit 10%). Toxicology was positive for sedating antihistamine diphenhydramine at 848 ng/mL in cavity blood and urine; the sedating antihistamine cetirizine was detected in muscle and liver tissues. Non-impairing blood pressure medications losartan and amlodipine were detected in cavity blood and urine.
Additional Information
The PA38 Service Manual stated: "A VERY THOROUGH INSPECTION OF THE ENTIRE EXHAUST SYSTEM, INCLUDING EXHAUST SHROUD ASSEMBLY, MUFFLER AND MUFFLER BAFFLES, STACKS, AND ALL EXHAUST CONNECTIONS AND WELDS MUST BE ACCOMPLISHED AT EACH 100 HOUR INSPECTION." It also noted that the entire exhaust system must be rigidly inspected each 100 hours, with the possibility of failure increasing with use, and more careful inspection recommended before winter operation when cabin heat will be used.
Tests and Research
In December 2021, the NTSB made recommendations regarding carbon monoxide detectors in enclosed cabin airplanes with reciprocating engines. Recommendation A-22-1 to the FAA: "Require that all enclosed-cabin aircraft with reciprocating engines be equipped with a carbon monoxide detector that complies with an aviation-specific minimum performance standard with active aural or visual alerting." Recommendation A-22-2 to the Aircraft Owners and Pilots Association and Experimental Aircraft Association encouraged members to be informed about carbon monoxide dangers and to install detectors with active alerting and ensure thorough exhaust inspection during maintenance.