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

APPENDIX E: ADIRU TESTINGTest plan developmentFollowing the 7 October 2008 occurrence, air data inertial reference unit (ADIRU)1 (unit 4167) was removed from VH-QPA at Learmonth, prior to downloading anydata or functional testing of other units on the aircraft. ADIRU 2 (unit 4687) andADIRU 3 (unit 4663) were removed after the aircraft was ferried back to Sydney,New South Wales. All three units were dispatched to the ADIRU manufacturer’sfacilities in Los Angeles, United States (US), and quarantined until the relevantinvestigation agencies had developed an agreed test plan.The test plan was developed collaboratively between the Australian TransportSafety Bureau (ATSB), the US National Transportation Safety Board (NTSB), theFrench Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile (BEA),the ADIRU manufacturer, the aircraft manufacturer, and the operator. The initialtesting was conducted with all organisations present, and subsequent testing wasconducted wherever possible under the supervision of the ATSB and/or the NTSB.When developing the test plan and conducting the testing, the following principleswere used:• All parties reached agreement on the necessary testing and the order of testingprior to test commencement.• Analysis of the available evidence was regularly performed and reviewed priorto proceeding with further tests.• Tests that could potentially result in the disturbance or loss of evidence (such asdamage to or reconfiguration of a unit) were conducted after other testswherever possible. For example, the removal of the ADIRU covers andre-seating of the circuit modules were considered disturbances of evidence asthey could affect the unit’s response to electromagnetic interference (EMI), sotests requiring such disassembly were performed after EMI testing.• The ADIRUs were tested as a complete unit prior to any module testing.• Where the validation of a test was required, the tests were performed on anexemplar ADIRU (serial number 4461) with the same configuration as thesubject ADIRU (4167).• All tests were conducted within the applicable quality assurance framework(normally that of the organisation performing the test).The final series of examinations and tests that were conducted on ADIRU 1 (serialnumber 4167) and the exemplar unit (serial number 4461) are summarised inTable E1 and discussed in the remainder of this appendix. ADIRU 2 (serial number4687) and ADIRU 3 (serial number 4663) were subjected to a basic series of testsnormally conducted on ADIRUs that were returned from service. As no problemswere identified during these tests, and there was no other evidence of a problemwith these units, (section 1.12.2 and 1.12.6) no further testing was conducted.- 243 -