What happened
On September 21, 2016, an Airbus A319-132, registration CC-COU, operated by LAN PERÚ S.A., was performing a commercial flight from Lima to Piura. During the initial takeoff and climb, the crew observed engine parameter fluctuations and received ECAM maintenance messages regarding the Engine 2 FADEC. While the aircraft reached cruise altitude and the parameters appeared to stabilize, the issues resurfaced during the descent phase at approximately 25,000 feet.
During the descent, the Electronic Engine Control (EEC) failed to properly command the Variable Stator Vanes (VSV) of the high-pressure compressor on Engine 2. The vanes remained stuck at a very closed angle, leading to an increase in Exhaust Gas Temperature (EGT), a drop in compressor discharge pressure (PS3), and a reduction in N1 and N1 speeds. This aerodynamic instability resulted in an engine stall, forcing the pilot to perform a commanded in-flight shutdown of Engine 2. After verifying engine conditions, the crew successfully restarted the engine. The flight crew, in coordination with the airline's operations center, diverted to Chiclayo to facilitate a better evaluation of the failure. The aircraft landed safely with both engines operating normally, and there were no injuries to passengers or crew.
The investigation
The CIAA investigation examined the aircraft's flight data, maintenance history, and the engine's electrical components. The investigation revealed that the aircraft had experienced several recurring maintenance alerts in the five flights preceding the incident, specifically related to the LVDT electrical signals.
Technical analysis by the engine manufacturer, IAE, focused on the electrical harness connecting the EEC and the VSV actuator. The inspection identified damaged insulation on the Channel A wiring, exposing it to intermittent contact. Additionally, excessive wear was found on the backshell of the Channel B connector, and a damaged rubber seal was noted on a connector pin. These findings suggested that the electrical degradation was likely caused by frequent handling and repeated disassembly/reassembly cycles during previous attempts to troubleshoot the recurring faults.
Findings
- The primary cause of the Engine 2 stall was erratic signals originating from damaged wiring and connectors within the electrical harness connecting the Engine Control (EEC) to the Variable Stator Vane (VSV) actuator.
- The electrical harness (Channels A and B) suffered from insulation damage and worn components.
- Contributing factors included the excessive manipulation of the VSV electrical connectors due to repeated component replacements during previous maintenance interventions.