The Piper PA-34 Seneca is an American twin-engine light aircraft, produced by Piper Aircraft since 1971 and still in production in 2008.
The Seneca is primarily used for personal and business flying.

The Seneca was developed as a twin-engine version of the Piper Cherokee Six. The prototype was a Cherokee Six that had wing-mounted engines installed, retaining its nose engine. The prototype was flown as a tri-motor aircraft in the initial stages of the test-flying program.

Certified on 7 May 1971 and introduced in late 1971 as a 1972 model, the PA-34-200 Seneca I, is powered by pair of Lycoming IO-360-C1E6 engines. The right-hand engine is a Lycoming LIO-360-C1E6 engine variant, the "L" in its designation indicating that the crankshaft turns in the opposite direction, giving the Seneca I counter-rotating engines. The counter-rotating engines eliminate the critical engine limitations of other light twins and make the aircraft more controllable in the event of a shut down or failure of either engine.