Piper PA-34 Seneca

PA-34 Seneca
Piper PA-34-200T Seneca II
Role	business and personal aircraft
Manufacturer	Piper Aircraft
First flight	25 April 1967
Introduction	1971
Status	In production
Produced	1971–present
Number built	5000+
Unit cost	US$799,000 (2009 base price)
Variants	PZL M-20 Mewa

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

The Seneca was developed as a twin-engined 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.

With the decision to abandon the three-engined design tested on the PA-32-3M, the PA-34 was developed as a twin-engined design. The prototype PA-34-180 Twin Six, registered N3401K first flew on 25 April 1967. The prototype had two 180 hp (134 kW) Lycoming O-360 engines, a fixed nosewheel landing gear and a Cherokee Six vertical tail. The second prototype flew on 30 August 1968, still with the 180 hp (134 kW) Lycomings but had retractable landing gear and a taller vertical tail. During development flying the wingspan was increased by two feet. The third prototype was closer to the production standard and flew on 20 October 1969; it was fitted with 200 hp (149 kW) Lycoming IO-360-A1A engines.

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 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. A total of 934 Seneca I models were built, including one prototype.

The early Seneca I models have a maximum gross weight of 4,000 lb (1,810 kg), while later serial numbers allowed a takeoff weight of 4,200 lb (1,910 kg).

Responding to complaints about the aircraft's handling qualities, Piper introduced the PA-34-200T Seneca II. The aircraft was certified on 18 July 1974 and introduced as a 1975 model.

The new model incorporated changes to the aircraft's control surfaces, including enlarged and balanced ailerons, the addition of a rudder anti-servo tab, and a stabilator bobweight.