Synopsis
A Piper PA34-220T (Seneca III), registration G-OBUC, was involved in a serious incident on 17 December 2021 over the Irish Sea near Co. Wicklow, Ireland. The aircraft was en route from Bournemouth Airport to Weston Airport when the right-hand engine failed. The pilot declared a MAYDAY, conducted a single-engine approach, and landed safely. No injuries were reported, but substantial damage occurred to the right-hand engine and cowlings.
Flight History
The aircraft departed Tatenhill Airfield at 11:50 hrs, stopped at Bournemouth for fuel and passengers, and departed for Weston at 13:30 hrs. While cruising at Flight Level 100, the pilot noted manifold pressure and fuel flow anomalies on the right-hand engine. After descending to 1,000 ft and passing Newcastle Airfield, the pilot reported a rough running engine and requested expedited arrival. Shortly after, a bang was heard, manifold pressure dropped, and the right-hand engine failed. The pilot secured the engine, feathered the propeller, and declared MAYDAY at 15:22 hrs. The aircraft was approximately 1.5 NM offshore at 700 ft. The pilot declined diversion to Baldonnel, opting for Weston's longer runway. At 15:28 hrs, the aircraft was handed over to Weston ATC, and the pilot performed a visual approach to Runway 25, landing without further incident.
Damage and Investigation
Examination by the AAIU revealed that the No. 3 cylinder had separated from the crankcase of the right-hand engine. Associated damage was noted to the crankcase and ancillary components. The separation was caused by the fatigue failure of seven of the eight cylinder retention studs/throughbolts. No injuries were reported, and there was no fire.
Probable Cause
The probable cause of the separation was the fatigue failure of seven of the eight cylinder retention studs/throughbolts.