What happened
On June 23, 2008, at 06:05 UTC, a Learjet 45, registration CS-TLW, operated by OMNI – Aviação e Tecnologia, Lda, was performing a non-scheduled passenger flight from Lisbon International Airport to Houari Boumediene Airport in Algiers, Algeria. The aircraft was carrying two crew members and five passengers.
During the initial climb, upon reaching flight level 90, the flight crew received an indication of an overheat condition in engine #2. Following standard safety procedures, the commander decided to abort the departure and return the aircraft to Lisbon.
The investigation
The investigation focused on the cause of the temperature warning in the cockpit. Following the return to the airport, the aircraft was inspected by maintenance personnel. The technical examination identified that the thermal blanket surrounding the engine #2 reactor ducting had degraded. This insulation component is designed to protect nearby heat sensors from the high temperatures of the gases passing through the ducting.
Findings
- The investigation established that there was no actual engine failure or malfunction within the engine itself.
- The overheat warning was a false indication caused by the degradation of the thermal blanket.
- The compromised insulation allowed heat from the reactor gases to reach a nearby sensor, triggering the overheat alert.
- After the thermal blanket was replaced, ground testing confirmed that the warning no longer occurred, and the aircraft was cleared for flight.