Aviation safety investigations & reports

Boeing Co 747-238B, 21977, 33 km N Brisbane, Qld, 26 December 1999

Investigation number:
199906038
Status: Completed
Investigation completed

Summary

While climbing through approximately 10,000 ft after take off, the crew of the Boeing 747-238, VH-ECB, heard an audible bang and felt a jolt through the airframe. The number 1 engine parameters were observed to fluctuate momentarily and the indicated Engine Pressure Ratio dropped by about .15 to 1.35. All other engine parameters remained normal and the aircraft remained free of vibration and control asymmetry. A visual engine inspection by the crew revealed nothing abnormal. After consulting with ground engineers in Brisbane, the crew decided to continue to Cairns. An inspection at Cairns revealed that most of the engine's cold stream nozzle was missing, a number of the outboard leading edge flap panels were damaged and the outboard flap canoe was holed.

The investigation determined that cracking and delamination of the acoustic lining skin at the top right side of the nozzle had been reported during the transit inspection at Cairns on 22 December 1999. An Engineering Authority had been issued to allow the aircraft to proceed after minor repairs to the acoustic liner were effected. The thrust reverser had also been locked out as a precaution and the aircraft then operated nine sectors before the nozzle failed.

The operator advised that delamination of the acoustic liner is a known defect. However, investigation determined that the cracking had originated in the nozzle structure adjacent to the acoustic liner. There is no requirement for inspection of this area during service. The area cannot be inspected in-situ without the removal of panels and the use of a visual aid.

A fleetwide check by the operator found a further six nozzles cracked in the same area. The nozzles were replaced before further flight. A detailed inspection of the removed nozzles determined that the cracking had originated at the top rivet hole of the standoff which supports the outer skin of the nozzle. The cracks varied in length from about 2 cm to 21 cm. The incident thrust reverser assembly, of which the nozzle formed part, had accumulated 19,621 hours since the last heavy maintenance inspection and 56,716 hours since new. The only inspection requirement is a visual inspection of the thrust reverser assembly at approximately 15,000 hours or shop visit when this area of the nozzle is visible. However, the nozzle assembly can be swapped between engines depending on the operators requirements. As the units are not serialised it is difficult to determine each nozzles time in service.

The manufacturer's recommended inspection requirements failed to detect cracking of the cold stream nozzle structure which resulted in failure of the nozzle.

 

Safety Action

As a result of this occurrence, the Australian Transport Safety Bureau (formerly BASI) made the following recommendations:

[ R20000004 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that Rolls Royce Commercial Aero Engine Limited notify all operators using Rolls Royce RB211-524D4 or similar engines of the possibility of failure of the cold stream nozzle during operation.

[ R20000005 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the United Kingdom Civil Aviation Authority notify all operators under their jurisdiction using Rolls Royce RB211-524D4 or similar engines, of the possibility of failure of the cold stream nozzle during operation.

[ R20000006 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the US Federal Aviation Administration notify all operators under their jurisdiction using Rolls Royce RB211-524D4 or similar engines, of the possibility of failure of the cold stream nozzle during operation.

[ R20000007 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that Rolls Royce Commercial Aero Engine Limited review Rolls Royce RB211-524D4 engine cold stream nozzle inspection criteria to minimise the possibility of failure during operation.

[ R20000008 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the United Kingdom Civil Aviation Authority review Rolls Royce RB211-524D4 engine cold stream nozzle inspection criteria to minimise the possibility of failure during operation.

[ R20000009 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the US Federal Aviation Administration review Rolls Royce RB211-524D4 engine cold stream nozzle inspection criteria to minimise the possibility of failure during operation.

[ R20000010 ] - The Australian Transport Safety Bureau (formerly the Bureau of Air Safety Investigation) recommends that the Civil Aviation Safety Authority review Rolls Royce RB211-524D4 engine cold stream nozzle inspection criteria to minimise the possibility of failure during operation.













General details
Date: 26 December 1999   Investigation status: Completed  
Time: 1010 hours EST    
Location   (show map): 33 km N Brisbane, Aero.    
State: Queensland   Occurrence type: Abnormal engine indications  
Release date: 17 January 2000   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 747  
Aircraft registration VH-ECB  
Serial number VH-ECB  
Type of operation Air Transport High Capacity  
Damage to aircraft Minor  
Departure point Brisbane, QLD  
Departure time 1005 hours EST  
Destination Cairns, QLD  
Last update 13 May 2014