A Piper Cherokee conducted a forced landing on a Sydney golf course after an exhaust valve broke in the aircraft's engine, resulting in a rapid loss of power, an ATSB investigation has found.
The accident occurred during a 17 August 2025 navigation training flight, which had taken off from Wollongong Airport with a student pilot and an instructor on board.
While around 1,600 ft above the coast north of Sydney, the crew heard unusual noises and observed a rapid drop in engine RPM.
"Fortunately, the instructor was proactive in maintaining an awareness of potential landing sites throughout the flight," ATSB Chief Commissioner Angus Mitchell said.
The report notes the instructor initially wanted to reach Long Reef golf course, with fewer trees, but maintained awareness of Mona Vale golf course being closer in case engine performance worsened.
"About six minutes into the occurrence, as the engine RPM progressively decreased, the instructor was able to determine that the safest option would be to conduct a landing on the Mona Vale golf course," Mr Mitchell said.
During the final stages of the approach, however, the pilot realised they had positioned the aircraft such that they could not safely land straight ahead, and so made a right turn to avoid the golf course facilities.
During the turn the right wing dropped. The aircraft subsequently landed heavily, resulting in substantial damage, and minor injuries to the student pilot.
Nonetheless, Mr Mitchell said, the pilot's prompt identification of a suitable forced landing site meant a worse potential outcome was avoided.
"This investigation highlights the importance of effective decision-making skills in emergency situations," he said.
The source of the engine failure was found to be the exhaust valve of the engine's number 3 cylinder, which broke away from its stem and caused extensive damage to the internal surfaces of the cylinder, its piston and spark plugs.
In this case, the cause of the exhaust valve failure could not be determined. However, the ATSB's final report notes the engine's manufacturer, Textron Lycoming, has provided maintenance practices to reduce the possibility of valve sticking.
"Operators and maintainers should be aware the risk of valve sticking is increased for engines operating in hot ambient conditions, and where engines are regularly shut down before they have cooled sufficiently," Mr Mitchell concluded.
After the accident, the training operator undertook several safety actions, including revising its emergency briefing content, completing a review of competency in conducting engine failure procedures for its instructors, and commencing a process to check students' post-engine failure competencies.
You can find here the final report: Loss of power and forced landing involving Piper PA-28, VH-BUN, 32 km north-north-east of Sydney Airport, New South Wales, on 17 August 2025
