Usually, we look for something greater than 60/80 when doing compression checks on Lycoming engines. A reading such as this one (36/80) really warrants further investigation. In this case, a borescope picture showed an exhaust valve that was in danger of imminently failing. It’s easy to find the air leakage when doing a compression test by placing your ear at either the oil filler tube (usually indicates leakage by the rings) or at the exhaust stack (will indicate exhaust valve leakage) or at the air intake (which will indicate a leaking intake valve).
In Case You Missed it
Engines of Change
It never fails to amaze me, this choice in powerplants for our Experimental aircraft....
Durand Reinstatement
Planning a kit for the unique Mark V negative-stagger biplane.
DIY Firewall Boots
Need to seal your firewall, reduce carbon monoxide and allow components to move freely? Chuck Dieterich shows you how to make firewall boots.
The State of Auto Conversions
We take a look at the current auto-engine conversions for homebuilt aircraft. By Patrick Panzera.