Accident Details
On November 4, 2021, about 0947 eastern daylight time, a Cessna 172A, N172XX, was substantially damaged when it was involved in an accident near Decatur, Georgia. The student pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The flight originated from Dekalb-Peachtree Airport (PDK) in Atlanta, Georgia.
According to the student pilot, before takeoff he added 1 quart of oil, bringing the total quantity to 8 quarts (full capacity). While at an altitude of 1,500 ft mean sea level, the engine began running roughly, followed by a total loss of engine power. The pilot pitched for best glide airspeed and declared an emergency with air traffic control. He attempted a forced landing to a four-lane road, but the airplane struck powerlines and came to rest inverted on the road. The accident site was located about 5 miles south-southwest of PDK.
Postaccident Examination
Postaccident examination at the site revealed that the exterior surface of the bottom fuselage skin was coated in oil from the engine compartment to the tailcone, and a hole was noted in the crankcase above the No. 6 cylinder. After recovery, fresh oil was found on the cockpit floor behind the firewall. In the rear portion of the engine, the oil filter adapter and its attached base had separated from the engine accessory case. The adapter did not appear to be safety wired, per the instructions in the manufacturer’s service bulletin. The separated portion of the oil filter, which was safety wired, exhibited impact damage. The oil suction screen contained some ferrous material, but no contamination was observed in the oil filter element. About 4 to 5 ounces of oil were drained from the oil sump, which contained metal. Examination of the accessory case revealed that the lower portion of the opening, into which the oil filter adapter threads, was fractured away. None of the smeared threads of the accessory case accepted the oil filter adapter, but some of the damaged threads of the oil filter adapter would have threaded into the accessory case.
Maintenance History
A review of the maintenance records showed that the airplane’s last annual inspection was completed in January 2014, more than 7.5 years before the accident. The Federal Aviation Administration inspector assigned to the investigation reported that the oil filter adapter was installed “sometime in 2020,” but this installation was not documented in the maintenance records.
Pilot Statement
In the National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident report, the student pilot indicated that there was evidence of the spin-on adapter being over torqued upon installation, which cracked the accessory housing. This crack never leaked but broke free on rotation at PDK, dumping all eight quarts of oil out of a hole over an inch in diameter, starving the crank and causing the rods to seize. The spin-on was installed by the airframe and powerplant mechanic that did the 100-hour inspection.