Rejected take-off

VH-WIL was operating in the circuit area at Port Lincoln for the purpose of testing the installation of a Mogas conversion. The LAME who had carried out the work was the pilot-in-command. He was accompanied by the owner who was seated at the right hand control position. After entering downwind for a touch-and-go landing on runway 23, the pilot, while testing the new fuel pump switch, inadvertently selected the master switch off. When the master switch was reselected, the VHF radio, which had been set to the MTAF frequency, defaulted to 121.5 Mhz. The pilot then selected an incorrect frequency. At the same time, VH-LNB taxied and lined up on runway 19 for departure to Adelaide after making all the necessary radio calls. VH-WIL made an approach and landed just past the threshold of RWY 23. As the pilot applied power again for take-off, the passenger sighted VH-LNB rolling on RWY 19. The pilot of VH-WIL aborted his take-off well short of the intersection of the two runways, selected the correct frequency and called VH-LNB.

The aircraft experienced a sudden uncommanded left yaw 10-15 knots below the V1 speed of 130 knots. The crew controlled the aircraft and rejected the take-off. The flight attendants seated in the rear of the aircraft confirmed the yaw was very abrupt. The FDR while recording the event did not disclose any information as to the origin of the signal that commanded the input that initiated the yaw. However, the FDR did disclose that the yaw was not a result of flight control input, therefore it is suspected that brake or nose wheel steering inputs may have been responsible. Parameters for these systems are not recorded on the DFDR. The company has introduced a strongly worded briefing to passengers about the dangers of operating electronic equipment during critical stages of flight although there was no evidence that this was the cause of this incident.

A Boeing 737 was cleared for take-off from runway 23 but was instructed to stop by the Tower controller because a Piper Seminole had inadvertently infringed the upwind end of runway 23 at 1000 ft AGL. The 737 had come to rest at the runway 12/23 intersection. During this sequence of events, a Saab 340 was on final for runway 12 and was instructed by the Tower controller to go around because the 737 was occupying the runway 12/23 intersection.

The Seminole had been cleared by the Tower controller to track for a left base runway 23. The pilot of the Seminole had inadvertently tracked for a right base runway 23 which brought the aircraft into potential conflict with the projected take-off profile of the 737. There was no breakdown in separation. When the Seminole pilot was instructed to turn inland, he thought that he was required to turn inland from the coast and then continue to track North across the extended runway 23 centreline to then join a right base for runway 23. The pilot kept thinking that he was following his clearance despite some anomalies in the instructions being issued to other aircraft such as the 737.

These cues elicited some concern by the Seminole pilot but the pilot did not take further action to clarify the significance of these cues. The pilot of the Seminole was instructed to track for a left hand circuit for runway 23 prior to infringing the extended runway 23 centreline. It is plausible that the pilot had regressed or been captured by his former more frequent habits (glider towing, general flying, and gliding) which required right hand circuits off runway 23 at Gawler airfield. The pilot's default mental model was right hand circuits off a runway 23 configuration. This strong habit intrusion, that is, the unintended activation of the strongest or most contextually frequent action schema most probably contributed to this occurrence.

VH-TJZ was cleared for a rolling take-off from runway 16 right (16R). During the take-off roll at approximately 40 knots IAS, the Tower controller cancelled TJZ's take-off clearance and instructed TJZ to hold position. TJZ was brought to rest abeam taxiway F with light braking. During this sequence of events, VH-EKN was on short final approach to runway 07 when the Tower controller instructed the crew to execute a go-around manoeuvre.

During the take-off ground roll at approximately 90 kts, the left engine ingested a Galah and the gas producer (Ng) speed reduced to below 60% accompanied by the ignition light illuminating. Power was reduced and the take-off was discontinued. Maintenance investigation found a bird carcass and feathers partially blocking the engine air intake. After removal and inspection for damage, ground runs were carried out to verify engine performance parameters, and the aircraft was returned to service.

As the aircraft reached approximately 20 kts during the take-off roll, no 2 engine failed. The take-off was rejected. No other damage to the aircraft was reported. The engine examination by the aircraft operator revealed that all first-stage blades had failed adjacent to their blade platforms. The damage was most likely caused by failure of blade No 35, which failed in high cycle fatigue emanating from the blade trailing edge. The operator experienced several similar failures previously. The engine manufacturer was aware of the problem and was undertaking corrective action.

Shortly after the take-off roll commenced, the crew aborted the take-off. The aircraft departed normally eight minutes later.

The operator advised that the crew received a take-off configuration warning (stabiliser trim) at the commencement of the take-off roll. The trim was reset using the co-pilot's control and the subsequent take-off was normal.

At Sydney, the aircraft had been released for service, prior to departure for Bangkok, with the number three engine fire detection 'B' loop inoperative, in accordance with the provisions of the minimum equipment list. The remaining 'A' loop would be used for fire detection and warning for the engine. The aircraft operated normally to Bangkok, where a transit service was performed before the next sector to Rome.

The subsequent take-off was rejected at 140 knots when the fire warning for number three engine activated. The aircraft returned to the gate where eleven of the sixteen mainwheels deflated due to overheating. The mainwheels were changed. Rectification of the fire warning problem consisted of repairing a broken wire at the 'B' fire detection loop connector, adjacent to number three engine starter motor. Both 'A' and 'B' loops then tested normally.

As the aircraft was rotated during the next take-off the number three engine fire warning activated again. The crew carried out the fire warning actions and shut down the engine. Fuel was jettisoned to bring the aircraft to maximum landing weight, prior to returning to Bangkok. An inspection of the engine revealed two holes burnt in the combustion case adjacent to the fire detection loops. The holes allowed hot gasses to escape and activate the fire warning system.

Investigation of the incident by the operator has resulted in a change to company procedures. Any rectification for a fire warning defect will now require a ten minute minimum high power ground run to verify the integrity of the engine. In addition, the inspection intervals for combustion cases have also been reduced.

During the take-off run, just before reaching V1, the crew heard two bangs in quick succession. Both the No 3 engine EPR and EGT indications were seen to fluctuate, so the take-off was immediately rejected. Whilst decelerating, the crew requested a frequency to communicate directly with the Rescue and Fire Fighting Service (RFFS) but were given the ground control frequency. That frequency was cluttered with other traffic, which made direct communication to RFFS difficult. They were finally referred to a different frequency. The aircraft vacated the runway onto taxiway Alpha 5 where a small brake fire was extinguished by the RFFS. The aircraft was subsequently towed back to the departure gate, where the passengers and crew disembarked.

Ground inspection revealed damage to several compressor stages of No.3 engine. The engine was changed, and the aircraft released for service.

Safety Action

The Bureau of Air Safety Investigation is evaluating aspects of a discrete air traffic services frequency on which aircrews and rescue firefighting services at airports can be transferred during an emergency situation. Any forthcoming recommendations will be published in the Quarterly Safety Deficiency Report.

The take-off was rejected when the left engine torque indication was noted to be 13% below target torque. The subsequent investigation found that a fuel control unit drive shaft seal failure had allowed fuel to wash the lubrication from the shaft bearings which then failed. The drive shaft and spacer were badly worn and had caused a restriction to the governor flyweights which had signalled the lower torque during take-off.