What happened
On January 15, 2007, at 04:20 UTC, a Lockheed L-1011 operated by euroAtlantic airways, registered CS-TEB, was lined up on runway 03 at Lisbon International Airport for a flight to Lagos, Nigeria. The aircraft was carrying 13 crew members and 16 passengers.
As the crew applied takeoff power, engine #1 responded with a delay, creating an asymmetric thrust condition that was managed using the rudder. During this period, an overboost occurred, with the Exhaust Gas Temperature (EGT) reaching 620 ºC. Approximately two to three seconds later, as the aircraft reached a speed of 120 kts, the crew heard two loud bangs accompanied by visible flashes from the exhaust nozzle of engine #3. The commander immediately decided to abort the takeoff, returning the aircraft to the apron for maintenance evaluation.
The investigation
The GPIAAF investigation focused on the mechanical failure of engine #3 and the performance of engine #1. Regarding engine #1, maintenance crews replaced the Sign Air Flow Control Unit, which resolved the thrust asymmetry issue.
For engine #3, a borescope inspection revealed significant damage to the high-pressure compressor (HPC) blades. The investigation established that the degradation of the abradable lining on the first stage of the HPC was the primary driver of the failure. While a previous inspection had noted minor degradation in this area, the deterioration progressed much more rapidly than anticipated, occurring within only 170 flight hours after the last noted issue.
Findings
- The failure of engine #3 was caused by the separation of the abradable lining from the first stage of the high-pressure compressor.
- Fragments from the disintegrating lining were ingested by the compressor blades, causing physical deformation.
- This deformation altered the aerodynamic airflow, reducing the stall margin and triggering a compressor stall.
- The degradation of the lining was attributed to a combination of chemical corrosion, thermal gradients, and exposure to the humid, saline environment characteristic of Lisbon.
- The investigation noted that while the operator followed maintenance protocols, the low frequency of aircraft usage and environmental exposure contributed to the rapid material degradation.