In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

1.17.2 Processes for reporting and monitoring aircraft faultsIf one of the operator’s flight crew noticed a fault or problem with an aircraftsystem or item of equipment, they were required to complete a technical log entry atthe end of each flight. 74 Faults or problems could also be detected by maintenancepersonnel when reviewing the aircraft’s PFR.Following the report of faults or problems, line maintenance personnel would assessthe available information, and conduct inspections and tests as required, using theprocedures and troubleshooting guidelines provided by the aircraft and/orequipment manufacturer. If the unit passed the required system tests, then generallyit would remain on the aircraft. If the unit did not pass the system tests, or therewere other reasons for concern (such as a recurring problem), the unit would beremoved from the aircraft and sent to the equipment manufacturer or an authorisedorganisation for examination.The operator used a database to record the technical log entries and the remedialactions taken by maintenance personnel. The database contained fields forrecording related information, including the aircraft registration, flight details, and anumber associated with the affected system or equipment. 75 However, the serialnumber of a unit was not recorded unless it was removed from the aircraft forexamination.The operator tracked the history of each unit in other databases. The main eventsthat were tracked were modifications (such as software updates), repairs, thelocation of the unit, and any movements of the unit (aircraft and position number).However, the history for each unit did not include reported faults or problems thatdid not result in its removal from an aircraft.The operator’s engineering department monitored the reliability performance ofeach type of system or unit across the fleet. This monitoring was based on statisticssuch as the mean time between unscheduled removals (MTBUR) and the mean timebetween failures (MTBF) (section 3.9.1). In addition to monitoring MTBUR andMTBF, the operator’s engineering department reviewed technical log entries toidentify repeating or related problems with a specific unit on an aircraft. Based onthis monitoring, a unit could be removed for more detailed examination.The operator’s procedures for reporting and processing system and equipment faultswere consistent with general industry practice.The aircraft manufacturer reported that, in its experience, recurrent issues wereidentified by operators, who then contacted the aircraft and/or systemmanufacturers. It also advised that there are a variety of forums and reviewmeetings that regularly occur involving operators and manufacturers which enablethe identification of potential issues or trends.In addition, the aircraft manufacturer noted that a specific cockpit effect ormaintenance fault message could result from an internal problem or a problemexternal to the relevant system. Accordingly, there can be problems trackingspecific types of messages (such as IR or ADR faults) and associating them with a7475As noted previously, the flight crew could report a problem of a more serious nature tomaintenance watch during a flight.The number was the Air Transport Association (ATA) chapter reference, with each chapterreferring to a different system.- 64 -