Description

On 25 August 2010, a Boeing 757-200 being operated by UK airline Astraeus on a passenger flight from Freetown Sierra Leone to London Heathrow was in the cruise at night in Instrument Meteorological Conditions (IMC) at FL370 when vibration levels on both engines increased. When the prescribed ice shedding drill was followed, one engine malfunctioned and vibration on the other remained abnormally high and so a MAYDAY was declared and a diversion to Nouakchott, Mauritania was made without further event. None of the 103 occupants were injured and there was no engine damage.

Investigation

An Investigation was carried our by the UK AAIB. It was noted that reporting of the incident by the Operator was delayed and that the failure to secure Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data was not in accordance with applicable regulations. It was also observed that, although QAR data had been recovered for use in the Investigation, provision of such data did not constitute an AMC compatible with regulatory requirements. It was found that at the time of the incident, Astraeus did not have a formal procedure for the preservation of the FDR or CVR but noted that this has since been rectified. During the replay of the QAR, it was found that there was an error on the Boeing FDR data frame conversion in respect of a parameter relevant to the Investigation.