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

They provided information for maintenance personnel on the status orfunctioning of the aircraft’s systems. A class 1 message was usually associatedwith one or more cockpit effect messages that were presented to the flight crewduring the flight. A class 2 message was not associated with any messagesprovided to the flight crew. 54The PFR had a number of limitations, including:• it only recorded information to the nearest minute• it only showed the first occurrence of a cockpit effect or a maintenance faultmessage (that is, a repeat occurrence of the same message would not be shown)• a correlation function performed by the CMS grouped together all of themaintenance fault messages associated with the same system 55 at the same time(within 1 minute), and it would only record the first fault that was detected(along with a list of other systems that detected the fault).The PFR from the flight recorded 22 cockpit effect messages that were presented tothe crew during the period from 0440 until the end of the flight. 56 These included 21different ECAM messages and a ‘flag’ message. 57 All were caution messagesexcept the AUTO FLT AP OFF warning message.Appendix C provides the complete PFR from the flight.ADIRU fault messagesThe two types of caution messages that could be displayed to the flight crew aboutan ADIRU problem were a NAV IR [1, 2 or 3] FAULT and a NAV ADR [1, 2 or 3]FAULT. These messages could be generated by the ADIRU self-detecting a faultand transmitting that information to the FWS, by the FWS detecting that the IR orADR parts had stopped transmitting data (that is, the data was not ‘refreshed’), orby another ADIRU detecting a problem (for the ADR only) and transmitting thatinformation to the FWS.The PFR for the flight showed two caution messages associated with the operationof the ADIRUs:• NAV IR1 FAULT (at 0440). Given that ADIRU 1 consistently flagged the IRparameters as invalid, it is likely that it self-detected the problem.• NAV ADR 1 FAULT (at 0513). Subsequent analysis determined that thismessage was generated by the IR part of ADIRU 3 (section 1.12.6) and not byADIRU 1 itself.54555657A class 2 maintenance message was associated with one or more ‘maintenance status’ messages,which were placed in the ‘cockpit effects’ column of the PFR even though they were not presentedto the flight crew. Class 3 messages were not recorded on the PFR but could be obtained from theCMS or the relevant system’s BITE.Fault messages were grouped by the Air Transport Association (ATA) chapter reference, witheach chapter referring to a different system. This categorisation is widely used in aircraftdocumentation.The ‘cockpit effects’ column of the PFR also included six ‘maintenance status’ messages. Thesewere class 2 maintenance fault messages and were not presented to the crew during flight.A ‘flag’ was displayed on the flight crew’s flight displays. When a flag was displayed there wasno associated ECAM message.- 46 -