Two UK engine failures
Engine 1 had 43 hours total since new
Engine 2 had 49 hours total since new
"Three cylinders and their associated pistons were taken to the Materials Department at QinetiQ (Farnborough) for detailed metallurgical examination. Examination of the three cylinders showed that No 3 piston and cylinder exhibited characteristics similar to the No 3 piston and cylinder from G-CEED. The piston/cylinder head interface exhibited sooting on one side of the cylinder, with the corresponding edge of the piston exhibiting burn-through (Figure 2). The internal surface of the cylinder showed evidence of minor wear and material pick-up from the piston at the point of the piston burn‑through. Skirt wear was observed on the piston similar to that observed in the examination of the engine from G-CEED. Minor wear was observed below the burn-through with the opposite skirt exhibiting more severe wear. The other two pistons both exhibited skirt wear similar to the No 3 piston. One of the pistons showed evidence of damage to the edge of the piston crown with reciprocating wear and material pick-up on the internal surface of the cylinder. The damage appeared to be purely mechanical, with no evidence of burn-through as seen in the No 3 piston.
Examination of the piston rings and oil scraper rings showed that the lower piston ring was seized in the closed position on one of the pistons and on another the upper ring was seized at the area of the damage, so that it was flush with the piston edge. The other end of the piston ring was free to move. On the No 3 piston both the lower piston ring and oil scraper ring were seized in the closed position."
Google this title (not a link) for full pdf report with pics
https://assets.digital.cabinet-offic...Jabiru__G-CEED.
Another excerpt from the report
Carburettor mounting effect on cylinder head temperature
A UK CAA-Licensed Aircraft Maintenance Engineer, and owner of a Jabiru-engined aircraft, conducted tests with differing angles of mounting the carburettor to the plenum chamber, and at the same time monitoring cylinder head temperatures (CHT) and exhaust gas temperatures (EGT). He found that by tilting the carburettor 10° to 15° left and right he could obtain a rise and fall in CHTs between Nos 1 & 3 cylinders and Nos 2 & 4 of up to 50°C and EGTs up to 120°C."