Incident Summary
On 4 August 2001, at approximately 1440 UTC, an Aerostar SA Yak-52, registration G-YAKY, suffered a loss of engine power five miles south of Carlisle, Cumbria. The aircraft was on a private flight from Bagby, North Yorkshire, to Carlisle Airport, flying in formation with another Yak aircraft. Both occupants—a pilot and a passenger—sustained minor injuries. The landing gear and both wings were badly damaged.
Flight Details
The aircraft had been refueled at Bagby before departure at about 1405 hrs. After takeoff, the passenger noticed fuel escaping from the left wing and informed the pilot. The pilot returned to Bagby, landing downwind, and discovered an incorrectly fitted fuel cap, which he re-secured. The aircraft then took off again, rejoined the other Yak at Penrith, and continued toward Carlisle in formation.
Emergency Landing
Five miles south of Carlisle, the engine lost power. The pilot informed the lead aircraft, which relayed a PAN call, later upgraded to MAYDAY. The engine continued running at idle. The pilot attempted several actions to restore power: applying carburettor heat, manually pressurising the fuel primer, cycling propeller pitch, and pumping the throttle. During this time, the passenger—an experienced pilot unfamiliar with the Yak type—took control, selected a field for forced landing, and positioned the aircraft. The pilot resumed control but found the approach steep with a high rate of descent. At a late stage, he deployed the landing gear partially to absorb energy. The aircraft struck the ground hard in a right-wing-low attitude with gear only partly deployed. The gear folded backwards, the aircraft slewed 90°, and came to rest within about 30 metres. Both occupants wore five-point harnesses. The passenger suffered a cut to his head but exited quickly; the pilot was uninjured and completed shutdown checks before vacating.
Engineering Assessment
Post-accident inspection found no obvious external signs of mechanical malfunction. A loss adjuster noted significant fuel in both wing tanks and fuel present through to the carburettor. The aircraft had flown only 4 hours since the engine—an imported, recently fitted overhauled unit—was installed. A rumour exists about possible preferential fuel draw from one tank on this type, but no evidence substantiated or denied it in this case. Weather conditions en route were clear with westerly winds and good visibility; the cloud base was estimated at 3,000 feet. Temperature and dewpoint at Carlisle were 18°C and 7°C respectively, suggesting a moderate risk of induction icing at cruise power.
Previous Occurrence
On 24 May 2001, a Yak 18A aircraft (RA01370) with the same engine type experienced a similar significant loss of engine power during cruise, as reported in AAIB Bulletin 9/2001.