Aviation safety investigations & reports

Cessna 150B, VH-DFN, 8 km south-east of Rylstone NSW, 3 August 1989

Investigation number:
198900014
Status: Completed
Investigation completed

Summary

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Following a preflight inspection the pilot departed from his property airstrip, climbing to approximately 1000 feet above ground level before setting heading for Mudgee via Tayar Peak. The pilot reported that the weather conditions were fine with a surface temperature of 6 degree Celsius and an estimated relative humidity of 75 per cent or greater. Shortly after passing Tayar Peak the engine began to run roughly and the pilot applied carburettor heat for approximately one minute. At the same time he changed his heading slightly towards Rylstone airstrip. The aircraft had now entered a natural basin surrounded by steep ridges, some up to 1500 feet above ground level. The engine returned to smooth running for a short time, then again commenced to run roughly before loosing power completely. With the propeller only windmilling the aircraft then descended below the surrounding ridge lines. Full carburettor heat was reapplied, but this failed to restore the power as the engine would have now cooled down, causing a lack of hot air through the carburettor heat system necessary to melt any ice accumulations. The pilot located a suitable area to carry out a landing, and during the approach sighted a power line, parallel and to the right of his track. On short final, with one stage of flap selected, he observed a branch power line which had previously been hidden by trees. It had a low, single wire spanning between poles across his flight path at 90 degrees. He attempted to descend beneath the wire but the right wing and strut collided with the wire causing the aircraft to rise and assume a steep nose down attitude before impacting the ground. The nosewheel assembly separated at initial impact and the aircraft continued for about 15 metres before coming to rest. The pilot, who was uninjured, evacuated through the left hand cockpit door which had sprung open. There was no evidence of any pre-existing defect which could have caused the engine to fail. The Carburettor Icing - Probability Chart, which has been published in the Aviation Safety Digest, indicated that the prevailing atmospheric conditions would have been conducive to serious carburettor icing at any power setting.

Download Final Report
[Download  PDF: 24KB]
 
 
 
General details
Date: 03 August 1989   Investigation status: Completed  
Time: 1300    
Location: 8 km south-east of Rylstone    
State: New South Wales    
Release date: 02 January 1990   Occurrence category: Accident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer Cessna Aircraft Company  
Aircraft model 150  
Aircraft registration VH-DFN  
Serial number 150 59 529  
Type of operation Private  
Damage to aircraft Substantial  
Departure point Capertee NSW  
Departure time 1230  
Destination Mudgee NSW