Friday, September 9, 2011

Failed Fuel pump Cessna 172


"(We saw) evidence of oil streaming down the belly and to the tail (of this 172S)," says this mechanic. "And oil was noted dripping from a drain tube below the firewall. This drain tube connected to an overflow fitting on the engine mounted mechanical fuel pump (P/N LW15473). The pump core was disassembled and oil was found leaking through the first of two diaphragms in this dual diaphragm pump. The rubber material covering the base material of the diaphragm was found flaking off. This base material is porous—allowing oil through the first diaphragm and into the ring chamber that allows oil to drain overboard without contamination of the fuel side of the pump. Failure of the second diaphragm would allow fuel injection to become contaminated. In a two month period, we have found two pumps draining oil overboard. A third aircraft was found with oil contamination in the fuel injection system." (curtsy: flight safety magazine)  

1 comment:

indian aviation now on line said...

the EDP drain tube is inspected during daily inspection for leakage of oil, if left unchecked leads to serious hazards