Singapore Airlines Flight 288 [SIA288] was maintaining Flight Level [FL] 310 on a flight from Auckland to Singapore. It had been cleared to transit Restricted Area R588 at FL 310 by Sydney Sector 5 who had correctly co-ordinated the clearance with Williamtown Approach control.

Four RAAF FA18A aircraft, operating as Shogun Section, had completed an exercise to the south of R588 and requested a clearance from Williamtown Approach control to return to Williamtown for a landing. The controller cleared Shogun Section to transit R588 at FL 310 from south to north on a course that was in conflict with SIA288.

As the aircraft approached each other, Williamtown Approach noticed the confliction and passed traffic information to Shogun Section, who then initiated evasive action by climbing above the level of SIA288.

The crew of SIA288 was not given traffic information by Sydney control but saw two FA18A aircraft and assessed that their own aircraft would pass behind. They therefore elected not to take any other action.

The aircraft passed within 2.7 NM of each other with 900 ft vertical difference. The required separation standard is 5 NM or 2,000 ft and, as such, a breakdown in separation occurred.

Significant Factors

1. The RAAF controller issued clearances for SIA288 and Shogun Section without correct application of the appropriate separation standards.

A passenger reported that incorrect techniques were used when refuelling the aircraft, with respect to the earthing of the aircraft. The report was correct, however, investigations revealed that the petroleum company and the CAA were in the final stages of negotiation to change the relevant Civil Aviation Orders (CAO's). Although not in accordance with the CAO's, the procedure used was not dangerous, according to the petroleum company representative and was acceptable to the CAA.

In the circuit area at Ararat the landing gear failed to extend. After two attempts to recycle, both hydraulic flow lights illuminated indicating loss of hydraulic fluid. The aircraft returned to Essendon where the landing gear was extended by the emergency system and the aircraft landed safely.

Hydraulic oil was leaking from the right wing root area. Investigation showed that an aluminium high-pressure pipe had fractured due to fatigue. The pipe was replaced with a flexible hose in accordance with a locally approved modification.

The flight proceeded normally until on approach to Adelaide Airport, when the pilot found he could not extend the landing gear. The emergency system was also tried but still no gear down indication could be obtained.

A wheels up landing was then made on runway 30.

Later inspection of the gear system revealed that on the last gear up selection a gear motor over-run had occurred. This caused the gear to be jammed in the up position and for the emergency gear extension mechanism to be damaged. The reason for the gear motor over-run was a defect in the dynamic brake relay which prevented the motor operation from ceasing in the normal up position.

Significant Factors

The following factors were considered relevant to the development of the incident:

1. A dynamic brake relay was defective.

2. The emergency gear extension system became damaged as a result of the defective dynamic brake relay.

After an uneventful landing, the aircraft veered to the left and ran off the side of the runway, despite the correcting control inputs from the pilot. The left wheel entered soft dirt and swung the aircraft further to the left, causing it to head towards an earthen bank. The pilot prevented the aircraft from hitting the bank by ground looping the aircraft, which damaged the aircraft by placing excessive side loads on the undercarriage. The pilot was familiar with the aircraft, and the wind was light and variable.

Shortly after take-off the warning annunciator for the 26V AC bus supply illuminated followed by a strong electrical burning smell. Power was removed from the bus and the smell diminished. After a successful landing the investigation disclosed that a power supply diode had overheated and failed.

The aircraft was undergoing a check flight after a 100 hourly inspection. It had not been used for at least 10 months, nor had it been stored correctly. After a number of simulated spray runs across the aerodrome the pilot climbed to conduct an approach to land. On late downwind at 350 ft agl the engine and propeller stopped. The pilot manoeuvred the aircraft towards a clear area but the aircraft landed heavily short of the area. The reason for the engine stopping was not determined.

The student pilot was conducting his third solo session of circuit training.

On the second circuit, which was to be a full stop, the aircraft encountered turbulence on short final which caused the aircraft to climb and drop a wing.

The pilot pushed the nose down then flared the aircraft. After touchdown, the aircraft bounced and began a series of purposing manoeuvres until the nose leg broke and the aircraft came to a stop with damage to the propeller, nose gear and tail skid.

When the pilot attempted to reduce propeller RPM from 2000 to 1900 the right propeller wound down to between 1100 and 1200 and the right torque exceeded maximum limits. The pilot shut down the engine and feathered the propeller when he was unable to regain control. A successful single engine landing was carried out.

The right engine beta light wiring was found to be routed close to the engine exhaust stack. Radiant heat from the exhaust stack had melted the insulation and had allowed the wires to contact and create an electrical short circuit. This had activated the propeller lock valve which effectively caused the propeller to operate at fixed pitch.

It could not be determined whether the burned wiring installation was installed in accordance with the manufacturers original design. A modification has now been incorporated to introduce fire sleeved wiring and a heat deflector baffle.

The aircraft had just taken off when the fire warning for the centre (No. 2) engine activated. The crew carried out the engine fire drill, shut down the engine and commenced a right hand circuit for a landing back on runway 23.

A distress phase was declared by the tower and emergency services alerted. On downwind, the crew advised that a fire was no longer evident. The aircraft landed without further incident, and the passengers were evacuated through the front doors.

Subsequent investigation revealed that a weld in the bleed air "Y" duct for the de-icing system of the engine intake had suffered a fatigue failure. This allowed hot bleed air into the engine compartment which activated the fire warning system. This type of failure has occurred before and there are Service Bulletins addressing the problem.