EC135
Flight Crew Commercial
Troubleshooting; Situational Awareness; Confusion
Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Flight Crew Diverted; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
Engine Number 2; Fuel Filter caution light illuminated during cruise. [Previous] night pilot experienced the same indication on Engine Number 1 the evening prior. Had Number 1 [Engine] Fuel Filter replaced this morning; which fixed that problem (no visible contamination found; though). Now the same indication on the other engine within 90 minutes of flight time. Engine Number 1 Total Time (T/T) is 2894+33; Engine Number 2 Total Time is 5218+34; so it is unlikely that both fuel filters are the same age and wear out within this short time frame in between each other. Suspecting fuel contamination. Fuel samples taken regularly at every shift change; no discrepancies noted. No suggestions. Part-135 revenue flight. Flight Nurse and Medic on board. Fuel filter light illuminated continuously. Air turnback and precautionary landing.
Reporter stated the helicopter involved was a Model EC-135T-1 with two Turbomeca Arrius 2B1 Engines. Fuel filters are metal type; not paper. They returned to their Base airport during the Air Turnback. Fuel samples are normally taken twice a day from the EC-135's fuel tank sump drain. Also the airport's Fuel Supplier tank was checked for contamination; including one of the hospitals where fuel was recently supplied to the EC-135. No evidence of fuel contamination was found from the samples taken.Reporter stated the Turbomeca Arrius 2B1 Engine Fuel and Oil Filters are located on top of their engine with a small access panel and a spy glass to view the filter pop-up indicators if either filter should become clogged. The Pratt PW-206B Engines have their Fuel and Oil filters at a different location not as easy to access. The EC-135T-1 model they fly do not have Fuel Flow or Fuel pressure indicators in the cockpit that could be helpful to refer to when the fuel filter caution light illuminates. He requested both engine fuel filters be replaced again and since then; no further pilot write-ups for fuel filter issues have occurred.
An Air Ambulance pilot reports that Number 1 and Number 2 Engine Fuel Filter caution lights had illuminated continuously on separate occasions during cruise flight on a Eurocopter EC-135 helicopter resulting in an air turnback. Fuel contamination suspected even though fuel samples taken regularly at every shift change.