Aviation occurrence briefs

Abnormal engine indications involving a Textron Aviation Inc. 172S, Moorabbin, Vic., on 9 September 2018

Status: Completed
Investigation completed


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 9 September 2018 at approximately 0845 Eastern Standard Time, a Textron Aviation Inc. 172S departed Moorabbin, Victoria (Vic.), to conduct a Flight Instructor’s rating flight to Tooradin, Vic. There were two crew on-board, the flight instructor as pilot monitoring (PM) and a student as the pilot flying (PF).

The aircraft was configured for a short-field take-off. On line-up, the crew reported the engine was run-up to full, showing 2,350 RPM and nil issues. The crew reported a normal take-off run, however on rotation, engine RPM and performance was observed to degrade. The RPM had dropped to approximately 2,000 RPM and minor engine vibrations were detected. The PF confirmed that the throttle was still fully open.

The crew determined that a landing back at Moorabbin was necessary and the PM took over as PF. Following this, multiple severe engine vibrations began to occur. An assessment to land on the remaining runway was made from approximately 100-150 ft from above the runway. The landing was reported as normal; however, the crew observed engine vibrations while taxiing and determined the vibrations did not occur between 700-800 RPM. The remaining taxi was completed with minimal braking and throttle adjustment, to roll the aircraft back to the apron.

While standing, the crew opened the throttle to 1,000 RPM and did not observe any vibrations. They also completed a magneto check with nil further issues.

The company maintenance inspection revealed the number 2 cylinder exhaust valve was partially stuck open contributing to the engine abnormalities. The cylinder was subsequently replaced. The inspection also found scorching on the exhaust valve with carbon deposits inside the guide.

At the time of the incident, the aircraft was at a flight switch of 98.2 from the last 100 hour service and 46.6 from the last 50 hour service.

Safety message

When emergencies present themselves, pilots need to be familiar with how to handle their aircraft as per their aircraft’s pilot operating handbook (POH).

If any aircraft malfunctions or abnormalities are detected, pilots should discontinue the flight and conduct a precautionary landing if it is safe to do so. In this instance, the crew followed their standard operating procedures and a safe outcome was achieved. Decisive actions by the crew meant that this situation was handled safely before the issue could escalate.

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.


General details
Date: 09 September 2018   Investigation status: Completed  
Time: 0845 EST    
Location   (show map): Moorabbin    
State: Victoria    
Release Date: 13 December 2018   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft model Textron Aviation 172S  
Type of operation Flying Training  
Sector Piston  
Damage to aircraft Nil  
Departure point Moorabbin, Victoria  
Destination Tooradin, Victoria  
Last update 31 July 2019