During the preflight check at Los Angeles, when the Standby Power switch was selected to Battery, the captain's electronic navigation displays went blank, the upper Engine Indication and Crew Alerting System (EICAS) display transferred to the lower screen, and an additional message 'Standby Bus Main' was displayed. It was later determined that the standby inverter was missing from the aircraft. Investigation determined that the inverter had been removed in Sydney on the previous day, to service another aircraft. Maintenance engineers involved with the removal did not raise the appropriate documentation as they were unaware of the requirements of the company Policy and Procedures Manual. No formal shift handover was conducted, consequently subsequent shift personnel were unaware of the missing component and released the aircraft for service. The aircraft was then flown to Los Angeles. During the departure preflight cockpit check at Sydney, the correct responses were displayed when the standby power test was performed but the crew were not alerted to the additional 'Standby Bus Main' message as the checklist does not mention it. EICAS display transfer to the lower screen was not noticed as the cockpit was sunlit and the captain's navigation instrument displays were selected to low intensity at the time. Significant factors: 1. The maintenance crew was unaware of the required documentation procedures. 2. The maintenance crew did not conduct a formal shift handover. 3. The cockpit checklist was deficient with regard to testing the standby power system. Safety action As a result of this investigation the operator advised that they had initiated the following safety actions in respect to the deficiencies relating to the training of certifying engineers on the requirements of the company Policy and Procedures manual: '1. The course notes for the LAME Introduction Course were distributed to all LAMEs including those at line stations. A where to find it booklet was also given to AMEs. These actions were completed by the end of August. 2. Maintenance Memo Number M1884 was issued to alert all LAMEs to their responsibility to follow approved procedures. It provided information as to which volume would be relevant to the particular work area. 3. In conjunction with item 2, Department Heads checked and in some cases improved the availability of the appropriate P.&P. Manuals in their areas. This was completed prior to the end of August. 4. In order to provide a concise and accurate analysis of incidents for those persons who need to know we have introduced a Quality Alert Bulletin. The objective of which is to ensure all benefit from the lessons learned. The information is depersonalised for obvious reasons. 5. While there was nothing wrong with the existing procedure for serviceable transfer (Vol. 5 chapter 3-40-05) we took the opportunity to emphasise its existence when it was revised. Maintenance Memo M1880 refers.' The Bureau of Air Safety Investigation made the following interim recommendations on 9 February 1994: IR940015 The Bureau of Air Safety Investigation recommends that the Civil Aviation Authority liaise with the Boeing Commercial Airplane Company, in conjunction with the Australian operator, to amend the B747-438 Flight Deck Preparation Checklist to include reference to additional EICAS messages that will be displayed when an unacceptable condition exists with the standby power system. The CAA response stated, in part: 'The Authority believes that the abnormal indication of the Captains display blanking and EICAS transfer to the secondary screen should have been sufficient indication that there was a problem with the aircraft systems. We do not believe it is reasonable to expect aircraft systems to compensate for abnormal maintenance actions and the range of inappropriate actions that are possible would make such an approach difficult to address. Nevertheless, the Authority will raise the matter of amendment to the B747-400 Flight Deck Preparation Checklist to highlight that further investigation of any unusual indications during flight deck preparation checks is necessary.' The operator response stated: 'I have enclosed a copy of a revised page for the 747-400 Operations Manual. This revision has been written as a result of the referenced A.S.I.R. The revision is highlighted by a margin line bar, and will be processed as part of a general revision to go to printing at the end of the week. Rather than make the comment specific to the Standby Power check, I have included it as part of the preamble to the whole flight deck preparation. I feel that this is more appropriate as there are potentially other areas where a similar problem could occur should these circumstances ever arise again.' IR940016 The Bureau of Air Safety Investigation recommends that (the operator) conduct a review of policy relating to shift handover procedures to include directions for individuals as well as supervisors. The operator response stated, in part: 'The reason the static inverter was not fitted to VH-OJB was that the engineer who removed the inverter failed to carry out the requirements of the Policy and Procedures manual in regards to not entering in the aircraft log book or work package that the inverter had been removed from the aircraft to service the other aircraft. By making an entry as required the person removing the item is also fulfilling the requirements of an individual handover as this entry has to be acquitted prior to the Maintenance Release being certified. After the investigation of this incident the engineer involved was counselled and disciplinary action was effected against him. As well the Policy and Procedures manual reference to the actions required when cannibalising aircraft components has been amended to clarify the requirements when carrying out this function. These procedures have since been widely distributed to all Sydney Line Maintenance staff.'