As posted in ATSB.
During the 11 June 2017 occurrence, one of the three structural intake cowling acoustic panels of a China Eastern Airlines Airbus A330-200’s left engine separated and was ingested into the engine shortly after take-off from Sydney Airport’s runway 34 Left.
The flight crew effectively maintained control of the aircraft, continued the climb while reducing the thrust setting to idle, and declared a PAN PAN. The crew maintained an altitude of about 6,000 ft as they manoeuvred the aircraft to reduce its fuel load and address technical issues from the incident.
After 42 minutes, the aircraft landed safely at Sydney in an overweight configuration, where emergency services were on standby. Debris from the inlet cowling was later found strewn along the runway and the aircraft’s flight path.
Occurrences like this highlight how effective flight crew training ensures crews are able to effectively respond to any situation
“This event demonstrated the effectiveness of the certification design requirements and flight crew training to ensure continued flight despite effectively losing the power of one of two engines during a critical phase of flight,” said ATSB Director Transport Safety Dr Stuart Godley.
On landing, damage was identified to the inboard side outer inlet cowling skin including the number 1 and number 2 acoustic panels as well as the engine’s fan blades and cold stream duct. Minor airframe damage to the left wing trailing edge flaps, landing gear door, and left side of the horizontal stabiliser was also identified.
With the panel and cowling debris ingested into the engine, there was limited physical evidence available to ATSB investigators.
“Despite extensive testing conducted by the engine and cowling manufacturers, the reason for the failure could not be conclusively determined,” Dr Godley said.
“However, it was considered that the most likely reason for the failure was a localised disbond between the acoustic panel facing sheet and the honeycomb core.”
The ATSB found this was the fourth event where an inlet cowling acoustic panel manufactured by Bombardier Aerospace fitted to an Airbus A330 with Rolls-Royce Trent 700 engines had failed and was ingested. The first incident occurred in October 2006.
In 2014, in response to these earlier incidents, Rolls-Royce introduced a modification for the acoustic panels that doubled their density and adhesive contact area with the inlet cowlings. There have been no recorded failures of the redesigned panels. However, a number of pre-modified inlet cowlings are still in operation (including the one involved in this event).
As a result of this incident, Rolls-Royce issued an amended service bulletin which introduced a new inspection regime with 12-month (rather than 24-month) intervals as well as revised damage limits and highlighting how to conduct a ‘tap test’ to identify acoustic panel damage, including delamination.
Amendments to the service bulletin were also incorporated into a European Aviation Safety Agency airworthiness directive.