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The flight was an international regular public transport operation between Sydney, Australia and Osaka, Japan on 19 October 1994. The technical crew consisted of a very experienced (B747) pilot in command who was also acting as a training pilot, an experienced co-pilot who had not yet completed his line training on the B747, and an experienced but newly B747-rated flight engineer who was on his first revenue flight as a qualified B747 flight engineer.

Approximately one hour after departure the crew shut down the number one engine because of an oil leak. They returned the aircraft to Sydney where the approach proceeded normally until the landing gear was selected. With selection of the landing gear and selection of the flap beyond a setting of flaps 20, the landing gear warning horn began to sound because the nose landing gear had not extended. The flight crew unsuccessfully attempted to establish the reason for the warning. Believing the gear to be down, the crew elected to complete the landing, with the result that the aircraft was landed with the nose gear retracted. There was no fire and the pilot in command decided not to initiate an emergency evacuation.

The investigation found that the oil loss was caused by the failure of a threaded insert used to retain the engine angle gearbox housing cover. The cover came loose, allowing oil to escape. An opportunity to action service bulletin SB JT9D-7R4-72-410, which would have prevented the oil leak had not been taken. Although the same engine is used on a number of aircraft approved for extended range operations over water, the manufacturer had not made the incorporation of this service bulletin mandatory. The owners of an aircraft can elect not to action a manufacturer's recommendation to incorporate a service bulletin.

An unexplained reduction in air-driven hydraulic pump output caused slower than expected operation of the number one hydraulic system. The system may still have been capable of extending all the landing gear, given adequate time. However, the aircraft landed before the system could complete the landing gear extension.

The flight crew had the opportunity to recognise and correct the landing gear problem prior to landing. The pilot in command attempted to determine the actual landing gear situation from the flight engineer. Although the flight engineer's panel indicated the nose gear was not down and locked, the flight engineer did not recognise this and subsequent communication and co-ordination between the flight crew failed to detect this error.

During the latter part of the flight, the crew did not adequately manage the operation of the aircraft. The crew's performance reflected a lack of effective crew resource management, the crew's lack of knowledge about some of the company's procedures for B747 operations, the flight engineer's and the co-pilot's lack of experience in the B747 and perceived pressure.

A review of events associated with the introduction of the B747 indicated that organisational factors involving both Ansett and the Civil Aviation Authority led to a situation where there was increased potential for an accident of this nature to occur. These factors included deficiencies in the planning and implementation of the introduction program for the new aircraft, particularly with respect to manuals, procedures and line training. In addition, all regulatory requirements were not observed, nor were they enforced.

The flight crew's performance combined with the organisational factors to breach defences that had been put in place to ensure the safety of regular public transport operations in high capacity aircraft.

A number of recommendations were made as a result of the investigation.

Ansett Australia has advised the Bureau that it has taken a number of significant actions in response to this occurrence. Details of the actions taken can be found in Section 4 of this report.

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