Aviation safety investigations & reports

Beechcraft C23, VH-UMH, 2 km South of Yan Yean Reservoir VIC, 1 October 1988

Investigation number:
Status: Completed
Investigation completed


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The aircraft was cruising at 1500 feet above the ground when the engine began to vibrate and the RPM dropped from 2400 to 1900. Even with full power selected the aircraft could not maintain height. The pilot planned a forced landing on to a stretch of trotting track. On final approach he realized that the aircraft was overshooting the planned touchdown point. He used the available engine power and landed in a 250 metre wide paddock adjacent to the trotting track. Braking was not fully effective on the damp grass surface. In the latter part of the roll despite an attempt to veer the aircraft to the left the aircraft penetrated a stock fence at very low speed. The underside of the mid-section of the left wing was damaged as it contacted a fence post which swung the aircraft to the left. Number one cylinder was found to have no compression. About half of the head of the exhaust valve had broken free and been ejected through the exhaust port. The exhaust valve had achieved 603 hours time in service since installation as a new item. There may have been a flaw in the exhaust valve since manufacture. The valve failure was considered to be an isolated occurrence.

Download Final Report
[Download  PDF: 23KB]
General details
Date: 01 October 1988   Investigation status: Completed  
Time: 1320    
Location: 2 km South of Yan Yean Reservoir    
State: Victoria    
Release date: 24 January 1989   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Beech Aircraft Corp  
Aircraft model 23  
Aircraft registration VH-UMH  
Serial number M-1824  
Type of operation Private  
Damage to aircraft Substantial  
Departure point Moorabbin VIC  
Departure time 1306  
Destination Wangaratta VIC