It was found during this accident investigation and another that following power loss, significant amounts of potentially useful data, covering key time periods during the flights, have been lost from temporary volatile’ memory buffers, prior to data transfer to the recording medium. There have been at least two cases where UK accident investigations have found that important QAR (Quick Access Recorder) parameters were lost due to recording buffers of up to 120 seconds. The UK AAIB report states that Although its primary purpose is not for accident investigation, data from HFDM (Helicopter Flight Data Monitoring) and FDM (Flight Data Monitoring) programmes has frequently been used in accident investigations. Use of memory buffers in these systems is not unusual but can present limitations when data is recovered.’