GE agreed that starter failures were not desirable (contained or uncontained), and has continued work to understand the failure and make improvements as noted. Relative to certification, of particular note is that the core compartment is defined as a fire zone (due to the presence of flammable fluid and a potential ignition source), so its boundaries are to be fireproof. As a result of work on a relatively recent engine certification program (different engine model), data was collected from a number of representative legacy in-service fires, which demonstrated they are of limited extent (size and/or duration). Furthermore, the associated oil volumes or quantities were relatively small, so that typical oil-related fires do not last very long, sometimes not even annunciated or alerted to the flight crew.
The action taken with regards to the change in design will eliminate those air turbine starter failures associated with single pawl and ratchet crash engagements, however it will not completely eliminate failures (contained or otherwise) from all causes. Nevertheless, as a result of these safety actions, the ATSB is satisfied that the likelihood and consequence associated with these starter failures will remain low.
Additional safety action
Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.