An EASA notice of proposed amendment (NPA) aims to improve the reliability of flight recorders. In particular, the aim of the proposal is to increase the robustness of flight recorders to the loss of their power supplies; prevent the premature termination of recordings due to the untimely triggering of negative acceleration sensors; and define the certification requirements for combination recorders and deployable recorders. Comments on the NPA are due by June 27.
Some accident investigations revealed that CVRs have depowered prematurely while they could have kept recording useful information if an alternate power source had been installed. In some cases both the flight data recorder (FDR) and the cockpit voice recorder (CVR) were powered by the same electrical bus, so that a failure of this bus disabled both recorders while the aircraft was still flying. The NPA would require that for newly manufactured aircraft, no single electrical bus failure can terminate the recording on both the CVR and FDR.
New rules would also require that the CVR and cockpit-area microphone are provided with an independent 10 minute backup power source, to which the CVR and cockpit-area microphone are switched automatically.
Several safety investigation agencies have reported reliability issues with negative acceleration sensors, or so-called "g-switches," which are used to stop the flight recorders after a crash impact. In several occurrences involving high levels of airframe vibrations, some g-switches were triggered prematurely and, therefore, recordings stopped before the end of the flight. The NPA proposes a specific reference prohibiting the use of g-switches as a sole means of complying with end-of-recording requirements.
The NPA also contains certification requirements for installation of combination recorders. A combined FDR/CVR recorder “provides savings in weight and maintenance costs,” EASA said. “Furthermore, when two combination recorders are installed, this can increase the likelihood that the FDR and CVR data are fully retrieved after an accident.”
Finally, the proposed requirements establish the basis for the certification of deployable recorders, a crash-protected flight recorder that is designed to automatically eject from an aircraft in the event of an accident. “The deployable recorder is a technology that can also greatly facilitate the localization of an aircraft after an accident over an oceanic area or a remote area because it is designed to be buoyant and fitted with an ELT,” EASA said.
