Aircraft Engine Compression Tester
An aircraft engine compression tester helps you turn a rough-running, hard-starting, or power-limited engine complaint into usable diagnostic evidence. The tool measures how well each cylinder holds pressure during cranking or under regulated shop air, which points toward ring sealing, valve seating, and head gasket condition. Choosing the right unit depends on the engine configuration you service, the test method you prefer, and how repeatable the gauge reads under real maintenance conditions.
The direct answer
For most owners evaluating a suspect cylinder, a direct-reading compression tester is the more straightforward purchase because it records peak cranking pressure after the ignition is disabled. The familiar numeric result works well for comparing all cylinders on the same engine, especially when symptom conditions such as a rough idle or weak acceleration appear only after the engine reaches operating temperature. A gauge that holds the peak reading until you release it reduces the chance of misreading a pulsing needle during a short crank cycle.
If your goal is to locate the loss path rather than simply confirm a low cylinder, a differential-style tester offers more diagnostic direction. It supplies regulated shop air through a calibrated orifice and reports leakage as a percentage, letting you listen at the intake, exhaust, or crankcase breather to separate ring wear from valve sealing problems. Either approach requires an adapter set that matches the cylinder openings on the engines you inspect, so check the included thread sizes and hose reach before buying.