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.
Speed: 162 Knots (75%, 6000 Feet)
Range: 820 NM / Time: 5.1 HRS (55%, 10,000 Feet)
Rate of Climb at Sea Level: 1360 FPM
Service Ceiling: 17,900 Feet
Single Engine Service Ceiling: 3,650 Feet
Takeoff Performance: 800 Feet (Ground Roll), 1235 Feet (Total Over 50 Foot Obstacle)
Landing Performance: 705 Feet (Ground Roll), 1335 Feet (Total Over 50 Foot Obstacle)
Stall Speed (KCAS): 76 Knots (Flaps Up, Power Off), 60 Knots (Flaps Down, Power Off)
Standard Empty Weight: 2778 Pounds
Maximum Useful Load: 1422 Pounds (Normal Category)
Fuel Capacity: 98.0 Gallons (Total), 93.0 Gallons (Usable), 49 Gallons (Total Each Tank), 46.5 Gallons (Usable Each Tank)
Oil Capacity: 8 Quarts (Sump)
Engine: Textron Lycoming IO-360-C1E6, and LIO-360-C1E6 / 200 BHP at 2700 RPM
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 righthand engine is 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. A total of 934 Seneca Is were built, including one prototype. The early Seneca Is have a maximum gross weight of 4,000 lb (1,810 kg), while later serial numbers allowed a take-off weight of 4,200 lb (1,910 kg).