RV-8
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 20; Flight Crew Total 9600; Flight Crew Type 15
Troubleshooting; Training / Qualification; Situational Awareness
Aircraft Equipment Problem Critical
General Maintenance Action
Aircraft
In preparation for an oil change; the aircraft was preflighted and flown to warm oil. Flight duration was 37 minutes. During flight all engine and aircraft parameters were normal. After shutdown while pushing back into hangar; oil was noticed dripping and puddling from the aircraft fuselage. Cowling removal showed the oil cooler ruptured and sprayed oil on lower cowl and firewall; with heavy streaming on the belly from the firewall to the tailwheel. Oil quantity from the streaming was sufficient to readily develop numerous puddles along the length of the fuselage. A review of the onboard electronic data log did not show any abnormal pressures. The highest value recorded for the entire flight was 86 PSI; well within design parameters for the engine and oil cooler. During preflight the dip stick indicated 4+ quarts oil. A post flight check indicated 2 quarts remaining. Post checks on the engine and oil system are not indicating any mechanical reason for a forced failure of the oil cooler. There are no signs of over pressure distortion anywhere on the unit; including the area of the leak. It is undetectable to the naked eye and can only be located by applying pressure to he unit. The flow pattern indicates this was an inflight failure that occurred in the last minutes prior to landing.
An RV-8 developed an oil cooler leak during flight which was only discovered after landing because of oil puddles. The cooler was a year old with in service time of 10.5 hours.