Faulty fuel probe wiring was apparently a key factor in an engine-out incident involving a Danish Air Transport ATR 42-500 on a night flight from Esbjerg to Billund, Denmark, on March 17, a preliminary report from the Danish Accident Investigation Board (DAIB) indicates.
The twin turboprop had just departed Esbjerg when the right Pratt & Whitney Canada PW127F engine flamed out at 1,000 ft, the DAIB said. After stabilizing the aircraft at 3,000 ft., the crew was unable to restart the engine but decided to continue to the destination airport, less than 30 nm to the northwest.
On its instrument approach to Billund, the cockpit instrumentation showed the left engine had failed and the autopilot disconnected, leading the captain to “rapidly move the left-engine power lever forward,” according to the report. Following that action, the cabin crew heard “loud bangs from the left engine” and saw fire on the aircraft’s left side.
The pilots landed and pulled off on a taxiway to evacuate the seven passengers and discharge the fire bottles of both engines. There were no injuries to the six crewmembers or the passengers.
Investigators determined the right engine failed due to fuel starvation, despite indications in the cockpit that more than 1,120 lb. remained in the tank. A right-tank low-level light, designed to activate when the fuel level in each tank is below 353 lb., also did not illuminate. Cockpit indicators for the left tank showed 904 lb. of fuel remaining—the amount investigators found in the tank.
After disassembling the right-side fuel-measurement system, which is composed of five probes for each of the two tanks, investigators found issues with a wire in Probe 3 for the right tank. After “manipulating” the wire, the fuel-level and low-fuel indicators began operating correctly, and investigators could not duplicate the problem.
Regarding the left-engine anomaly on landing, the DAIB said a visual inspection “revealed no findings.” A borescope inspection, while uncovering “incrustation, deposits and sod on the internal parts of the engine,” did not reveal any internal mechanical faults. The DAIB’s probe continues.