An rv-8 developed an oil cooler leak during flight which was only discovered after landing because o...

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1055137
Time
Date	201212
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	RV-8
Operating Under FAR Part	Part 91
Flight Phase	Parked
Route In Use	Direct Visual Approach
Flight Plan	None
Component
Aircraft Component	Oil Cooler
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 9600 Flight Crew Type 15
Events
Anomaly	Aircraft Equipment Problem Critical

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.