Introduction
On 14 August 2019, a Cessna F172N aircraft, registration LZ-SPB, operated by Air Operator Avio Detachment Varna Ltd., was involved in a serious incident at Lesnovo Airfield, District of Sofia. The aircraft was performing a training flight when the engine failed shortly after takeoff. The crew landed safely without injury.
Flight History
Departure and Route
The aircraft departed Lesnovo airfield at 09:50 hours local time (07:50 UTC) for a training flight in the designated training area above the Iskar Dam. The flight was planned to return to Lesnovo.
Crew and Preflight
The crew consisted of a commander-instructor and a trainee pilot. Preflight inspection was conducted in accordance with the Pilot's Operating Handbook. Fuel quantity was 41 US gallons, and oil level was 5.3 quarts. No leaks of fuel or working fluids were observed. The trainee pilot performed the preflight check, which was recorded in the aircraft technical logbook.
The Incident
During climb at approximately 3,600 feet (QNH), the trainee pilot noticed smoke emanating from the left side of the dashboard. The instructor decided to abort the training task and return to Lesnovo. The trainee pilot initiated a right-hand turn at the instructor's command, and during the turn, vibrations occurred in the engine area. The instructor took control of the aircraft.
As the aircraft approached a forced landing on Runway 10 at Lesnovo, the engine shut down three to four seconds before touchdown. The crew completed a successful landing. After landing, they switched off the master switch, ignition, mixture, and fuel tap. The landing time was recorded as 10:55 local time, with a total flight duration of 8 minutes.
Post-Landing Findings
Upon exiting the aircraft, the crew observed that the aircraft fuselage was covered with oil. The aircraft was towed to the maintenance hangar of Avio Detachment Varna Ltd. Inspection revealed the engine oil filter had torn from the adapter plate.
Damage to Aircraft
The aircraft sustained damage: the engine shut down due to loss of oil pressure. The engine oil filter was torn from the adapter plate.
Cause
The serious incident was caused by tearing of the engine oil filter from the adapter plate for its attachment to the engine crankcase, resulting from plastic deformations in the mounting sleeve related to violations of repair and/or maintenance technology.
Injuries
No injuries occurred among the crew.