Uploaded on Oct 12, 2010
Post major maintenance/life extension at Yak UK Ltd a YAK 50 loses oil pressure over the Lake District at 1250ft. Engine runs until dry before seizing, gearbox u/s and windmilling prop at 3100ft followed by glide, wheels up as per ops (no flaps on the 50) into a rough field with an upslope of 12-14 degrees at 500ft amsl.
First impact to full stop 47 metres, first belly impact approx 35 metres.
Aircraft did not go through a wall, starboard aileron did contact with a fence post.
Wind reported at Carlisle less than 5kts - windmills visible not turning and shutdown. Ground soft. When the engine seized it caused the reduction gearbox to disintegrate hence a windmillling prop and engine shut down with mags off and fuel cut. On inspection the cylinders completely solid, engine core since scrapped. Aircraft repaired and will be airworthy. US 'Strong' parachute worn.
Camera Contour HD 1080i. Lens 135 degree view
Watch video: http://www.bremont.com/mayday.php
Yakovlev Yak-50, G-YAKK: Bothel, Cumbria - Engine out forced landing video
Pilot: Andy Wilson
Bremont Watch: ALT1-P/BK
Location: Bothel, Cumbria
Date of occurrence: 10 April 2010
Category: General Aviation - Fixed Wing
Details: The aircraft was on a local flight from Carlisle Airport when the engine failed due to loss of oil pressure. The windscreen became partially obscured with an oil film but the pilot was able to make a forced landing in a field, during which the aircraft was substantially damaged. He vacated the aircraft unaided, but later attended hospital as his injuries became more apparent. On examining the engine, the pilot identified that the oil pressure adjustment valve was missing from the oil scavenge pump housing. It was found in the lower cowling with no evidence of the expected wire locking. He believed that the valve had worked loose and fallen out during the accident flight, causing the oil loss. The aircraft had recently undergone extensive maintenance at EGMJ which included an overhaul of the oil scavenge pump assembly. Initial flights following this work revealed a small oil leak in the area of the pump, which at the time, was thought to be have been remedied by an engineer tightening the small vertical bolts adjacent to the pressure adjustment valve.
To see the AAIB FULL REPORT please got to www.AirCrashObserver.com
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