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The Australian Transport Safety Bureau has issued a Safety Advisory Notice to operators of the Beechcraft Baron, urging them to inspect the aircraft's heater fuel line to ensure electrical wiring is not rubbing and chafing against it.
The Safety Advisory Notice has been released in conjunction with a preliminary report from the ATSB's on-going investigation into an accident involving a Baron aircraft which experienced an in-flight fire on approach to land at Kununurra Airport, north-west Western Australia, on 16 April 2022. The aircraft was operating a charter flight from Broome with a pilot and one passenger on board.
The report, which details factual information from the investigation's early evidence collection phase, outlines that while conducting a straight-in approach to Kununurra's runway 12, soon after selecting the landing gear lever to the down position, the pilot received unusual indications and then detected an electrical burning smell and smoke emerging from below the left side of the aircraft's instrument panel.
"Continuing the approach, the pilot made a 'PAN PAN' urgency radio broadcast, activated the SOS alert on the aircraft's Spidertracks flight tracking unit, and switched off electrical power, by which stage flames were present," ATSB Director Transport Safety Stuart Macleod explained.
"The pilot then discharged the on-board fire extinguisher at the flames, however the fire almost immediately returned, filling the cabin with smoke and obscuring the pilot's view of the instrument panel and outside environment."
Shortly after, recorded data showed that the aircraft diverged significantly to the left of the runway centre line and crossed the Ord River at low level. The aircraft then collided with the ground about 600 m beyond the river and about 800 m from the runway threshold, and was consumed by fire.
The pilot, despite sustaining serious injuries, was able to extricate themselves and the passenger from the wreckage. Sadly, the passenger later succumbed to their injuries.
"Due to the severity of the post impact fire ATSB investigators were not able to conduct a complete wreckage examination," explained Mr Macleod.
"However, investigators were able to establish evidence of engine rotation prior to impact, while finding no evidence of pre-existing defects to the engines or flight controls that could have contributed to the accident."
Further, the aircraft's landing gear was observed to be stowed.
Mr Macleod said that given the extent of fire damage to the aircraft wreckage, determining the circumstances of the fire initiation and development is challenging and remains under investigation.
However, the ATSB previously investigated an in-flight fire involving a Beech 58 in February 2014.
"Two pilots were conducting a ferry flight from Darwin to Gove, when the pilot in the left seat observed smoke and flames by their left leg adjacent to the circuit breaker panel," said Mr Macleod.
The left-hand seat pilot immediately switched off the electrical master switch and discharged the fire extinguisher at the flames, while the right-hand seat pilot took control of the aircraft and conducted an emergency descent and landing.
"A post-incident engineering inspection found that wiring had penetrated the heater supply fuel line, causing it to arc out and burn a hole in the fuel line."
Given the similarity of some of the circumstance of the 2014 incident to the April 2022 Kununurra accident, the ATSB is advising Beech Baron operators to conduct a detailed inspection of the aircraft's heater fuel supply line and nearby wiring.
"It is important to stress that the ATSB's investigation into the Kununurra accident is on-going, and we are yet to make formal findings as to the accident's contributing factors," Mr Macleod said.
"However, given what we do understand of this accident, we believe it is prudent for Baron operators to examine the area below the pilot's circuit breaker panel and areas forward of this under the instrument panel.
"The ATSB also encourages operators to report any identified issues to the Civil Aviation Safety Authority and the aircraft manufacturer."
Mr Macleod said a final report, which will detail safety analysis and findings, will be released at the conclusion of the investigation.
"However, as we have with the release of this preliminary report and Safety Advisory Notice, if at any time as the investigation continues we are made aware of safety critical information, the ATSB will immediately share that with relevant stakeholders so that they may take appropriate safety action."
You can find here the report: AO-2022-026 In-flight fire and collision with terrain involving Beechcraft B58 Baron, VH-NPT near East Kimberley Regional Airport, Kununurra, Western Australia on 16 April 2022
You can find here the SAN: AO-2022-026-SAN-001 Beechcraft Baron heater fuel supply line inspection
Last update 21 September 2022
