Coolant Blow Out...
This 912 ULS with 1320hrs in a Tecnam SLSA has developed a coolant leakage problem. After pressure testing the system and replacing several aging leaky hoses including new clamps and replacing the expansion tank cap with a new cap and checking that the overflow bottle line and bottle were clear and making sure the overflow bottle cap vent was open the engine still needs to have coolant added after every flight. No coolant leaks on the hanger floor, but it seems coolant is leaking in flight with evidence of coolant on the firewall and blowing out the cowling. Before each flight, the expansion tank is checked to make sure it is full and the overflow bottle is serviced to halfway between the min and max marks. After a short flight with the engine still warm, before it has a chance to cool and suck the coolant back into the expansion tank the overflow bottle is found empty. Coolant is found around the overflow bottle cap and on the firewall. Could there be a cylinder head crack leaking combustion pressure into the cooling system? How about the coolant system pump? From my time working with automobiles I know, there is a testing tool for checking if combustion is leaking into the cooling system. But if such a test is performed to find which cylinder is bad the spark plugs have to be shorted one cylinder at a time. If you disconnect and or short out a set of plugs on one cylinder so it is dead will that damage the CDI ignition system?
Jeffrey Fritts, USAF (ret.)
www.flywwlsa.com
"In aircraft maintenance, good enough is not good enough."
