History of the Flight
The aircraft was climbing out after takeoff from Shoreham Airport when the engine stopped at about 1,100 ft. The pilot, the sole occupant, executed a forced landing. During the descent, he selected a field containing sheep, as the alternative had power lines. On touchdown, the aircraft struck three sheep, killing them, then ran through a fence and into trees, where it came to rest with partial separation of the rear fuselage and collapsed nosewheel. The pilot exited and warned bystanders of possible fire, though none occurred. The flight was a private hour-building sortie; the pilot had performed pre-departure checks and a normal takeoff from Runway 20. During climb, he noted a transient drop in rpm to 95% and later a complete loss of engine power with less than 2% rpm indicated. He attempted to restart the engine unsuccessfully.
Engine Examination
Engineers from the aircraft's maintainers examined the engine and downloaded FADEC data, which showed low fuel rail pressure alerts. Visual inspection revealed that the No 2 cylinder injector securing screw and injector support were missing; the injector was displaced about 50 mm and the fuel pipe unions had loosened. The injector had been replaced on 24 February 2015 to rectify a seal leak. The maintenance records showed a new securing screw was requisited per the manufacturer's repair manual. The manual, revised in July 2014, required a thread repair (helicoil insert) before a third injector change. The maintenance staff stated they were aware of this requirement but relied on the engine log book, which did not record all removals and refits. After the accident, a new screw could be torqued correctly into the cylinder head thread, indicating the thread was likely not stripped. The copper injector seal was also missing.
Discussion
The cause of the engine power loss was loss of fuel pressure due to a loose fuel injector. Neither the securing screw, injector support, nor seal were recovered. The manufacturer's tests suggested that without the copper seal, high temperatures from leaking gas could compromise the screw's self-locking feature. The exact reason the screw loosened could not be determined. A previous similar incident involving an Italian-registered DA 40 had been investigated, with the manufacturer proposing possible causes including fluid contamination in threads, incorrect torque, or failure to replace the single-use screw. In this case, a new screw had been used, but the missing seal remained unexplained.