Turned-back Qantas plane had issues on previous flight

A Qantas plane flying from LA to Brisbane that was forced to turn back when sparks were seen coming from an engine had issues on its previous flight to the US, it can be revealed.

A Qantas plane at the Brisbane International Airport. Picture: David Clark

A Qantas plane flying from Los Angeles to Brisbane that was forced to turn back just three hours into the flight had engine vibration issues on its previous flight into the US, an air safety investigation has found.

The national carrier’s internal communications are now being examined as part of an Australian Transport Safety Bureau probe into the incident on December 4 last year.

Flight QF16 from LA to Brisbane turned back after sparks were seen coming from one of the engines.

A preliminary report released by the ATSB on Thursday found that the Airbus A330-200 was cruising at about 34,000 ft after departing Los Angeles when a passenger reported sparks coming from the right engine.

“After conducting a number of checks and considering alternate airports, the flight crew opted for a return to Los Angeles, and descended the aircraft to 31,000 ft to reduce load on the engine,” ATSB chief commissioner Angus Mitchell said.

“By the time the aircraft reached this altitude, the intermittent sparks were observed to have stopped.

“Later, as the aircraft was descending to land in Los Angeles, three loud bangs were heard, and there was a right engine compressor stall indication.

“In response, the flight crew operated the engine at idle for the rest of the descent and landing.”

Mr Mitchell said a post-flight inspection of the right engine identified a missing high-pressure compressor blade that had separated at its root, another high-pressure compressor blade fractured about half-way up, and damage to the tips of several other blades.

A variable stator vane was also found to be out of alignment, and there was metal debris in the engine’s exhaust.

The aircraft was subsequently grounded, and the right engine replaced.

The preliminary report detailed that, on the aircraft’s previous flight into Los Angeles, the flight crew had observed “a high N2 vibration advisory”.

N2 refers to the rotational speed of a jet engine’s high-speed spool, which consists of the high-pressure compressor and the high‑pressure turbine connected by a concentric shaft.

“During the turnaround in LA, two maintenance engineers troubleshooted the N2 vibration issue, during which they observed particles in the right engine exhaust,” Mr Mitchell said.

“The ATSB’s ongoing investigation is considering the communications between involved personnel during this troubleshooting, including communications between staff in Los Angeles and at the Qantas maintenance operation centre in Sydney.”

He said the troubleshooting culminated in the aircraft being allowed to fly with its N2 vibration sensor inoperative in line with “minimum requirements” - meaning vibration readings were not available to crew on the return flight to Brisbane.

“Flight crew for the incident flight told the ATSB they were not aware that particles had been observed during the examination prior to their flight,” Mr Mitchell said.

He said that as well as the communications and maintenance during the turnaround in LA, the ATSB’s ongoing investigation would examine the recorded data, maintenance procedures and records, and the outcomes of the material failure analysis being conducted by GE Aerospace on relevant components of the engine.

Mr Mitchell said a final report would be released at the conclusion of the investigation, including findings and any identified safety issues.

“Should a critical safety issue be identified during the course of the investigation, the ATSB will notify relevant parties immediately so appropriate and timely safety action can be taken,” he said.

Originally published as Turned-back Qantas plane had issues on previous flight