What happened

On 12 October 2011, the pilot of a Robinson R22 helicopter, registered VH-JNP, was performing aerial work near Saxby Downs in Queensland, when he heard a rattling noise behind the cabin and noted that the clutch light had illuminated. The pilot opened the clutch actuator circuit breaker and, at the same time, noted a burning rubber smell, prompting him to make an immediate precautionary landing and shut down the helicopter.

What the ATSB found

The problems with the helicopter’s drive system were traced to the clutch assembly where a group of MS21042L-4 locking nuts on the drive belt upper sheave had cracked and fractured. This premature nut failure had stemmed from the likely embrittling effect of residual hydrogen generated during the cadmium electroplating process applied during manufacture. The nut failures consequently led to a series of mating part failures and a breakdown of the clutch assembly, producing the symptoms experienced by the pilot and prompting the precautionary landing.

Importantly, after recognising the aural and visual warnings of problems developing with the helicopter’s drive system, the pilot followed the required emergency procedures and made an immediate and safe precautionary landing. Taking this prompt, prescribed action limited the damage sustained and very likely prevented a more serious outcome.

What was done as a result

At the time of this occurrence, the brittle failure of MS21042L-series nuts was an emerging airworthiness issue and several associated safety actions had already been implemented. In August 2011, 2 months before this occurrence, the helicopter manufacturer issued Service Letters alerting owners, operators and maintenance personnel to the potential for cracking of MS21042L-series self-locking nuts and requiring the immediate replacement of any cracked nuts found during inspections. The service letters had been issued in response to reports of cracked nuts being discovered on Robinson and other helicopter types.

On 12 October 2011 (the date of this occurrence), the Australian Civil Aviation Safety Authority (CASA) issued an Airworthiness Bulletin (AWB 14-002), alerting pilots and maintenance personnel of the need to closely monitor the condition of high-strength steel hardware (such as these nuts) with a view to identifying any failures that may have resulted from hydrogen-induced cracking.

On 4 April 2012, the manufacturer of the specific MS21042L-series nuts in question issued a Technical Quality Notice Bulletin, addressing in detail many procedural improvements that were being introduced to reduce the potential for hydrogen-related failures of this nut type.

Safety messages

A potentially serious accident was avoided by the prompt actions of the pilot, who recognised the symptoms of a drive system malfunction and promptly followed the emergency procedure requirements by landing immediately.

This occurrence highlights the importance of maintained vigilance during pre-flight and maintenance inspections, where close attention must be paid to the condition of all components within the helicopter’s critical flight systems. It also highlights the importance of pilots and maintenance personnel remaining attentive to the release of any information regarding new or emerging airworthiness issues that may affect the safety of their flight operations.

On 16 October 2011 at 1033 Coordinated Universal Time, a Boeing Company 747-438 aircraft registered VH-OJS, operated by Qantas Airways departed Suvarnabhumi Airport, Bangkok, Thailand on a scheduled passenger flight to Sydney, Australia. Shortly after take-off, the flight crew reported hearing a loud bang and experiencing vibrations and abnormal indications from the No.3 engine. The flight crew shut the engine down and declared a PAN before returning the aircraft safely to Bangkok.

Disassembly and inspection of the engine revealed that the engine failure was as a result of the release of a single, stage 7, intermediate pressure compressor blade from the compressor disc slot. The factors contributing to the blade release are the subject of an ongoing investigation by the engine manufacturer. If further information becomes available relating to the engine failure, the ATSB will update this report.

Aviation Short Investigation Bulletin - Issue 11

On 15 October 2011, a Cessna Aircraft Company 182P, registered VH-TIS, departed Ayr, Queensland on a private flight within the local area. On board the aircraft were the pilot and five passengers.

On descent from 1,000 ft into Ayr Aeroplane Landing Area (ALA), the pilot noticed a bird to the left of the aircraft, followed almost immediately by an impact with the windscreen. The bird penetrated the windscreen causing it to shatter.

The pilot selected full power, but the aircraft was unable to maintain altitude. Approaching 200 ft, the pilot selected a cane field to conduct a forced landing. TIS came to a stop and the pilot and passengers were able to exit the aircraft through the jump door and the windscreen. The pilot and passengers sustained minor injuries.

Following the birdstrike, the pilot focused on maintaining control of the aircraft. The decision to make a controlled landing into a cane field resulted in a safe outcome.

While it is difficult to prevent birdstikes, a number of proactive measures can be taken by both pilots and airports to reduce the risk. These include not flying at times of known high activity (usually dusk), looking for bird activity in the vicinity of the airport prior to departure and actively reducing bird attractants (water and food sources) from the airport surroundings.

On 23 February 2011, an Airbus A330‑203 aircraft, registered VH-EBL, was being operated by Qantas Airlines on a scheduled passenger flight from Perth, Western Australia to Sydney, New South Wales. During the latter part of the take-off, the aircraft yawed suddenly and unexpectedly and the pilot in command rejected the take-off. Following braking, smoke and some flame emitted from the main wheel area, but emergency services were not required to apply any extinguishing agent.

The investigation found that there was no aircraft‑related problem, and the unexpected aircraft yaw was probably due to a lateral wind gust.

No organisational or systemic issues that might adversely affect the future safety of aviation operations were identified. However, the occurrence does provide a timely reminder of the risks associated with rejected take-offs at relatively high speeds, such as wheel fires. Pilot awareness of their potential exposure to sudden and unexpected lateral wind gusts during take-off may increase the likelihood of pilots differentiating between a lateral jerk to the aircraft and the effect of an engine failure.

The Papua New Guinea Accident Investigation Commission (PNG AIC) is investigating a double propeller overspeed and impact with terrain, followed by a fire that occurred 33 km south-east of Madang, Madang Province, Papua New Guinea on 13 October 2011. The accident involved a Bombardier DHC-8-108 aircraft, registration P2-MCJ, with two pilots, a flight attendant, and 29 passengers on board. Twenty-eight passengers sustained fatal injuries during the accident sequence, one passenger survived with serious burns and all three crew survived.

The investigation is being carried out in accordance with Papua New Guinea's obligations as the State of Occurrence under Annex 13 to the Convention on International Civil Aviation Aircraft Accident and Incident Investigation (Annex 13). Shortly after the accident, the PNG AIC requested Australian Transport Safety Bureau (ATSB) assistance in the conduct of the investigation by providing investigator support, technical advice and facilities support.

In accordance with paragraph 5.23 of Annex 13, the ATSB appointed an accredited representative and a number of advisers to assist the PNG AIC. To facilitate this support, the ATSB commenced an external investigation under the Transport Safety Investigation Act 2003 and assisted the AIC during the on‑site phase of the investigation, in the technical examination of a number of recovered aircraft items and components, with the download and analysis of the aircraft’s flight data and cockpit voice recorders and as requested by the AIC during the remainder of its investigation.

The PNG AIC is responsible for and will administer the release of the final investigation report into this accident. Any enquiries in respect of the ongoing AIC investigation should, in the first instance, be directed to:

Mr David Inau
CEO, PNG Accident Investigation Commission

Telephone: +675 323 2911 and 323 2151
Facsimile: +675 323 2139

Email: dinau@aic.gov.pg

Address:
Accident Investigation Commission
C/- PO Box 1489
Port Moresby
National Capital District
Papua New Guinea

______________

Released in accordance with section 25 of the Transport Safety Investigation Act 2003.

At 1500:51 Eastern Daylight-saving Time on 8 October 2011, a breakdown of separation (BOS) occurred 59 km north-east of Armidale, New South Wales between a Boeing Company 737-8FE (737), registered VH-YVA, and a Gulfstream Aerospace Corporation Gulfstream IV (G-IV), registered VH-CGF.

Both aircraft were under radar surveillance and subject to an air traffic control (ATC) service. The aircraft were on reciprocal tracks on air routes that intersected about 35 NM (65 km) north-east of Armidale.

The Australian Transport Safety Bureau (ATSB) established that the controller's mental model for separation correctly identified the situation and included a plan to manage the traffic. However, the instructions that were issued to the pilot of the G-IV contradicted that mental model in that the controller cleared the G-IV for descent through and below the level being maintained by the 737. The progression towards the BOS continued when the controller did not recognise the error during the G-IV pilot's read-back of the clearance.

Ultimately, the controller's earlier correct level input into The Australian Advanced Air Traffic System allowed a system alerting function to activate. In response to that alert, the controller initiated compromised separation recovery actions to recover the required separation standard.

The ATSB identified a number of human factors and individual work processes that contributed to the occurrence. In addition, a safety issue was identified in respect of differences in the traffic alert phraseology between the Manual of Air Traffic Services and Aeronautical Information Publication (AIP). These differences increased the risk of non-standard advice being provided to pilots by controllers during compromised separation recoveries.

In response to this safety issue, Airservices Australia (Airservices) amended the AIP to enhance understanding of the criticality of any safety alerts and avoiding actions being provided to flight crew. This amendment came into effect on 28 June 12.

Abstract

At about 1450 on 11 October 2011, the third mate on board the Panama registered woodchip carrier Universal Gloria suffered burns to his hands and face when the air compressor he was using to fill an oxygen breathing apparatus (OBA set) cylinder exploded.

The ATSB investigation found that the explosion occurred as a result of a fire that started within the compressor when oil ignited in the hot oxygen-rich environment.

The investigation identified three safety issues. The crew were not appropriately trained or drilled in the operation and maintenance of the ship's OBA sets; the ship's safety management system did not provide the crew with appropriate guidance in relation to the operation and maintenance of the OBA sets; and there were no engineering controls in place to prevent the inadvertent connection of an OBA cylinder to the air compressor.

Section 21 (2) of the Transport Safety Investigation Act 2003 (TSI Act) empowers the Australian Transport Safety Bureau (ATSB) to discontinue an investigation into a transport safety matter at any time. Section 21 (3) of the TSI Act requires the ATSB to publish a statement setting out the reasons for discontinuing an investigation.

On 12 October 2011, the ATSB commenced an investigation into the breakdown of separation, between an Airbus Industrie A320 aircraft registered VH-VGR and a Boeing Company 737 aircraft registered VH-VOD near Melbourne Airport, Vic. Examination of the information collected during the investigation identified that the occurrence had significant similarities to aspects of ongoing investigation AO-2010-104, breakdown of separation, between a Boeing Company 767 aircraft registered VH-OGU and a Boeing Company 737 aircraft registered VH-VBH, near Melbourne Airport, Vic on 5 December 2010.

Accordingly, the ATSB decided to examine the 12 October 2011, breakdown of separation event as part of the broader investigation AO-2010-104 and the separate AO-2011-131 investigation was discontinued.

On 20 September 2011, a Cessna Aircraft 550 Citation II aircraft, registered VH-INT, was involved in a ground towing accident when a Fokker F100 under tow collided with the tail of the parked Citation. The collision resulted in damage to the left elevator, rudder and rudder trim control surfaces that necessitated the Citation undergoing repairs.

On 06 December 2011, while conducting a post-maintenance flight, the crew experienced control problems. The resulting post-flight inspection found several maintenance procedural omissions and rigging inconsistencies.

A review of the maintenance system and processes for return to flight and the acceptance flight versus training flight protocols was conducted respectively by both the maintenance and operator organisations and corrective actions taken.

Preliminary report released 19 December 2011

This preliminary report details factual information established in the investigation’s early evidence collection phase and has been prepared to provide timely information to the industry and public. Preliminary reports contain no analysis or findings, which will be detailed in the investigation’s final report. The information contained in this preliminary report is released in accordance with section 25 of the Transport Safety Investigation Act 2003.

Abstract

At about 0105 on 11 October 2011 an empty (northbound) ore train (1901S) travelling on the interstate main line from Pelican Point (Outer Harbor, South Australia) to Rankin Dam (Coober Pedy) passed signal 13 at Dry Creek Junction displaying a stop (red) indication. Train 1901S subsequently collided at low speed approximately mid-consist with a loaded (southbound) grain train (5132S) that was traversing a turnout at Dry Creek Junction to enter the Dry Creek North Yard in South Australia.

There was no injury to the train crews as a result of the collision. There was significant damage to the crew cab of the lead locomotive of train 1901S and to the grain wagons of train 5132S that were struck during the collision.