The flight crew quick reference handbook did not include sufficient information for the flight crew to appropriately manage operations on standby power.
Action taken by the aircraft operator
As a result of this occurrence, the aircraft operator:
- evaluated the provision of additional formal guidance to 747‑400 flight crew for operations on standby power, including a review of Section 6 - electrical of the non‑normal checklist within the 747‑400 quick reference handbook (QRH). On 30 April 2009, the aircraft operator reported that it did not plan any changes to the QRH unless recommended to do so by the aircraft manufacturer
- has drafted an addition to the 747‑400 flight crew operations manual to provide guidance to flight crews on the effect and management of multiple AC electrical bus loss, including battery life, major systems affected, and recommended crew actions.
Action taken by the aircraft manufacturer
In response to this occurrence, the aircraft manufacturer has performed several evaluations for the provision of additional formal guidance to 747‑400 flight crew for operations on standby power, including reviews of Section 6 ‑Electrical of the non-normal checklists in the 747‑400 QRH. On 29 October 2010, the aircraft manufacturer reported that 'due to the results of these evaluations and the subsequent mitigating changes made to protect the MEC and manage fluid spills, it does not plan any changes to the QRH.' The aircraft manufacturer provided the following justification:
[The aircraft manufacturer], in conjunction with the FAA, continually reviews and updates the FCTM.[1] The FCTM is provided to Operators who decide when and how to train and distribute the information to their crews. During ATSB's investigation, [the aircraft manufacturer] attempted to develop a Non-Normal Checklist (NNC) which would provide flight crews with guidance when the airplane is on standby power. NNCs are used by the flight crew to cope with non-normal situations. The NNC topics are organized to match that of the Systems Descriptions of the FCOM[2] Vol 2 chapters. Numerous non-normal situations are covered for each system chapter. Although every attempt is made to establish necessary NNCs, it is not possible to develop checklists for all conceivable situations, especially those involving multiple or remote failures. [The aircraft manufacturer] spent a significant amount of time and resources to try and understand the problem and develop a NNC but they were unable to come up with a NNC that would cover the subject event for all 747 configurations in the fleet. Further, [the aircraft manufacturer] believes that one NNC cannot be useful as well as correct for all conditions that might lead to the situation (on standby power).
ATSB assessment of action
The ATSB acknowledges the reviews already undertaken by the aircraft operator and manufacturer and action to amend the operator's operations manual to include guidance to flight crews on the effect and management of multiple AC electrical bus loss, including on battery life. The ATSB recognises that the various crew alerting systems in the 747‑400 should inform flight crews of any aircraft systems that are be affected by electrical systems failures.
However, there is currently limited assurance that 747-400 flight crews would be aware of the expected duration of available battery power or of the possible need to expedite appropriate actions such as aircraft diversion that should be undertaken in the event of abnormal or unexpected battery discharge. The inclusion of a note or caution associated with the battery discharge message entry in the QRH to alert crews of the restricted battery life in such cases would help crews select and prioritise the most appropriate actions to recover from the emergency.