What happened
On June 15, 2016, a Jet Airways ATR 72-5 and registration VT-JCL was operating a scheduled flight from Bangalore to Mangalore. Shortly after takeoff from Runway 27, the flight crew observed a brief master caution warning. While the aircraft was climbing through approximately 6,000 feet, cabin crew reported the presence of light white smoke in the passenger cabin. The crew initiated smoke checklists and requested a return to Bangalore.
As the aircraft continued its descent, the situation escalated. Passengers reported seeing flames on the right-hand engine. At approximately 1,200 feet altitude, the cockpit received a formal engine fire warning for the No. 2 engine. The crew activated the fire extinguishers and issued a MAYDAY call. The aircraft landed safely on Runway 27, and an emergency evacuation was immediately conducted. While the crew and most passengers were unharmed, 3 passengers sustained minor injuries during the evacuation process.
The investigation
AAIB India investigators examined the aircraft's engines and flight data recorders. The investigation focused on the mechanical state of the right-hand engine and the maintenance history of the fleet. Examination of the engine revealed that several components had suffered significant damage, including fractured blades on the second-stage power turbine and cracks in the bearing vent tubes. The investigation also reviewed the maintenance records regarding specific inspections and service bulletins.
Findings
- The primary cause of the smoke in the cabin was the contamination of the bleed air by engine oil. This leakage occurred because the air/oil seals of the turbine shaft and impeller bearings failed.
- The seal failure was driven by heavy vibrations resulting from the failure of power turbine blades.
- Specifically, one blade fractured due to fatigue, while another failed due to overload.
- Failure to perform a required Eddy Current Inspection and the decision not to implement a service bulletin for chromium-coated blades were identified as contributing factors to the incident.