| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 30 June 2020 at 1055 Western Standard Time, a Cessna 402 departed Groote Eylandt Airport for a charter flight to Darwin, Northern Territory (NT). There were two crew and five passengers on board.
During cruise at 10,000 ft, the aircraft experienced a rough running engine. The pilot began to troubleshoot the issue and observed the oil pressure dropping to zero. A short time later, the no. 1 engine sustained a total power loss.
The pilot completed the emergency checklists for the engine failure, contacted Brisbane Centre air traffic control and declared a PAN PAN.[1] The aircraft was diverted to Jabiru Aerodrome, NT and emergency services were organised for the arrival. The pilot then notified the passengers of the incident and planned diversion.
Prior to joining the circuit at Jabiru, the pilot reviewed the one engine inoperative checklist and planned the approach for runway 09. The aircraft landed without further incident.
Engineering inspection
The engineering inspection revealed the engine’s no. 5 cylinder piston had failed due to detonation. When the contaminates from the piston entered the crankcase[2] and the sump, engineers suspect that the volume of the contaminates blocked the oil pick up scavenge screen and the pump ran dry. This was evidenced by lack of oil in the oil filter canister.
The no. 1 and no. 2 connecting rod big end bearings on the crank journal ran dry and once the bearings started to break down, the extreme heat and pressure stretched the no. 2 connecting rod bolts which then failed. Both connecting rods failed and contacted the top of the crankcase, leaving a hole in the case and breaking off the left magneto.
Safety message
This incident highlights the importance of flight crews maintaining awareness of all system states and being prepared to act as early as possible. In this incident, the pilot was quick to identify and troubleshoot the engine failure and followed procedures to ensure a safe outcome.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
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- PAN PAN: An internationally recognised radio call announcing an urgency condition which concerns the safety of an aircraft or its occupants but where the flight crew does not require immediate assistance.
- Crankcase: A crankcase is the housing for the crankshaft in a reciprocating internal combustion engine. The crankcase provides an enclosed volume for the crankshaft motion and piston connecting rods to move and operate.