AAIB Bulletin: 7/2015

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46 ©Crown copyright 2015 AAIB Bulletin: 7/2015 G-CCHD EW/G2015/03/02 ACCIDENT Aircraft Type and Registration: DA 40 D Diamond Star, G-CCHD No & Type of Engines: 1 Thielert TAE 125-02-99 piston engine Year of Manufacture: 2003 (Serial no: D4.051) Date & Time (UTC): 7 March 2015 at 1700 hrs Location: Approx 4 miles west of Shoreham Airport, West Sussex Type of Flight: Private Persons on Board: Crew - 1 Passengers - None Injuries: Crew - None Passengers - N/A Nature of Damage: Rear fuselage partially detached, damage to right wing, propeller and nosewheel Commander’s Licence: Private Pilot’s Licence Commander’s Age: 28 years Commander’s Flying Experience: 126 hours (of which 31 were on type) Last 90 days - 4 hours Last 28 days - 0 hours Information Source: Aircraft Accident Report Form submitted by the pilot Synopsis The aircraft was climbing out after takeoff when the engine stopped at a height of about 1,100 ft. In the subsequent forced landing, three sheep were killed and the aircraft was badly damaged. It was found that a fuel injector and its unions had become loose and caused a total loss of fuel pressure. It could not be determined how the injector support and its securing screw had come undone as neither were recovered. History of the flight The purpose of the flight was to build the flying hours of the pilot, who was registered as a student at the flying school which owned the aircraft. Prior to departure from Shoreham, he performed all the required checks and completed the necessary paperwork before taxiing for takeoff on Runway 20. During the initial climb the aircraft’s performance and all indications appeared normal and, at a height of about 600 ft agl, the pilot executed a planned 90º climbing turn to the right. However as he reached approximately 1,000 ft, he sensed a slight reduction in engine noise and saw a drop to about 95% rpm from the full power selected. Although this appeared to correct itself, he commenced a precautionary wide turn to the right in anticipation that he might have to return to Shoreham. Upon reaching about 1,100 ft, he sensed another drop in noise which reduced to silence after a few seconds, with less 47 ©Crown copyright 2015 AAIB Bulletin: 7/2015 G-CCHD EW/G2015/03/02 than 2% engine rpm indicated. With the sea to his left and a built-up area below him, he steepened the right turn towards north and open ground whilst trying to restart the engine without success. With only two suitable fields to choose from, he had to select one which contained a flock of sheep, since the other had power lines obstructing it. As he touched down in the muddy field the aircraft struck three of the sheep, killing them before it ran through the boundary fence and into another field containing trees. As the left wing struck one of the trees, the aircraft was spun through 90º anticlockwise before coming to a halt with the rear fuselage partially detached and the nosewheel collapsed. The pilot shut down the aircraft and exited normally in time to warn a couple who had come to help to stay clear in case of fire (he recalled he had smelt burning during the descent). There was no fire and, whilst the couple called the emergency services, he called the flying club to advise them of his situation. Engine examination Engineers from the aircraft’s maintainers arrived at the site and checked fluid levels and downloaded the data from the engine FADEC (Full Authority Digital Engine Control) unit. Although at first it visually appeared that nothing was wrong with the engine, the data for the accident flight showed a series of alerts for low fuel rail pressure. The next day, upon closer inspection, it was found that No 2 cylinder injector securing screw and injector support were missing, the injector itself was out of position by about 50 mm and the associated fuel pipe unions had loosened (Figure 1). 1 2 3 Figure 1 Photograph of intact assembly showing Injector (1), Injector Support (2) and Securing Screw (3). (Photo courtesy Technify Motors) 48 ©Crown copyright 2015 AAIB Bulletin: 7/2015 G-CCHD EW/G2015/03/02 The injector had been removed and replaced on 24 February 2015 in order to rectify a leak from its injector seal. The spares invoice for this task indicates that, in addition to a new sealing ring, the injector securing screw was also replaced as required by Technify Repair Manual RM-02-02 Chapter 73-10.05 Issue 3. The same section of the manual, revised in July 2014, also specified the following: ‘Note: Before a third injector change – the Repair of the Thread for Injector Attachment must be done. Refer to Chapter 73-10.10’ The repair involved insertion of a helicoil insert into the female thread. The manufacturer has advised that this requirement arose from a case that occurred earlier in 2014 in which an Italian registered DA 40 suffered an engine failure and subsequent successful forced landing. Like G-CCHD, the FADEC data showed a loss of rail pressure occurring at the moment of failure. Physical examination revealed that an injector was similarly displaced and the screw and support were also displaced but were still present. Investigation by the Italian Authorities and the manufacturer showed that the thread in the aluminium cylinder head had stripped. The manufacturer decided that the corrective action would be to do the thread repair at the third injector change, hence the revision of Chapter 73-10.05. It was not felt necessary to issue a Service Bulletin or similar to highlight this change and it was noted that Chapter 73-10.10 did not refer to the third injector change requirement and remained dated December 2013. The maintenance company stated that the staff involved in G-CCHD’s injector removal on 24 February 2015 were aware of the repair requirement, but were using the engine log book to ascertain how many times the injector had been changed. However, the log book was