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PA-34 Seneca

PA-34 Seneca (5)

The Piper PA-34 Seneca is an twin-engined light aircraft. It began production in 1971 and still being produced.


Piper Seneca III-V

Piper Seneca III-V

July 2005- One time-tested way to create a light twin is to take a single, remove the engine, and replace it with two engines on the wings. Sometimes the engines are smaller than those on the single—as in Piper’s Twin Comanche. Sometimes the engines are as powerful as that on the single—as in the Beech Baron.

Piper took the first approach with the PA-34 Seneca: it’s basically a Saratoga airframe with the 300 hp single engine replaced by two 200 (later 220) hp wing engines. The result is one of the longest-running twins in General Aviation.

The original Seneca was introduced in 1972, and you can still buy a brand-new Seneca V from Piper today. The original PA-34-200 Seneca had some problems, notably a low single-engine service ceiling.

Seneca Chronicle Part 02

Seneca Chronicle Part 02

August 2013

Piper had success with its twin-engine Seneca, but complaints of poor handling had plagued the early models and Piper had been on a quest for more power and better handling for the Seneca nearly from the outset.

Seneca II

To gain more power for the 4,200-pound (gross weight) Seneca, Piper engineers looked at the possibility of adding a supercharger. They tried out the 220 hp Franklin 6A-350-C1 as well as turbocharged engines from Lycoming and Continental. In tests the 200 hp turbocharged Continental L/TSIO-360-E performed well and was eventually chosen for the powerplant.

In-flight handling was improved by adding aerodynamically balanced ailerons, an anti-servo tab for increased rudder effectiveness and a redesigned stabilator, while ground handling received enhancements in the form of a reworked nosegear steering linkage. To keep things simple engineers chose a fixed wastegate.

Seneca Chronicle Part 01

Seneca Chronicle Part 01

July 2013

If at first you don’t succeed, don’t “tri” again. But Piper’s trimotor testing wasn’t all for naught.

What do you do when you’ve completed initial testing of a new version of your wildly popular single-engine aircraft? If you’re Piper Aircraft in the 1960s, you slap a couple more engines on it and try it out as a trimotor.

That’s just what happened in 1964. Piper had completed initial tests on its PA-32-260 Cherokee Six and used that airframe to attach two more engines to the wings (in this case using the 115 hp Lycoming O-235) while retaining the 250 hp Lycoming O-540 of the “Six” for the center engine.

The Smart (and Sexy!) Seneca

The Smart (and Sexy!) Seneca

July 2012

A flood at the Piper’s Lock Haven facility destroyed the tooling for the Comanche, and Piper Aircraft developed the Seneca as a replacement aircraft for its popular Twin Comanche. Employing “parts bin” engineering and following the marketing strategy of the time, the Seneca is probably most accurately described as a twin-engine Cherokee Six.

Seneca Mods

Seneca Mods

October 2004 -

When I bought 1176X four years ago, I really did not plan to restore or modify the aircraft in any way, but as I got into the project, I discovered that there are more than 50 Supplemental Type Certificated products or modification for the PA-34-200T.
These STCs can be for things as simple as a better sun visor to as complicated as a vortex generator set that actually changes the way the aircraft flies. After careful consideration, I selected the STCs that I felt yielded the best "bang for the buck."
Maintenance issues compelled me to purchase the Bogart Oil Filter Access Door STC. This modification allows you to perform an oil change, including the filter, without dropping the lower cowl.
Copper starter cables were purchased because the factory-installed aluminum cables drew so much current that the aircraft was difficult to start under any conditions. The copper cables were so effective you could almost taxi the airplane on the starter motor alone.
The one-piece windshield and Rosen sun visors came with the aircraft, though I would have opted for both of them. The same for the JPI engine analyzer. I don't see how you can properly operate a turbocharged piston engine without one.
The Nayak auxiliary nacelle tanks were also installed on the aircraft when I purchased it. This mod brings total fuel capacity to 128 gallons.

 In pursuit of more speed, I invested in the Knots 2 U flap gap seals, wheel fairing kit, aileron and flap hinge cover kits, as well as the LoPresti axial flow cowls. They delivered as advertised and my Seneca beats the book numbers by 10 knots regularly at all altitudes below 10,000 feet, and more as I go higher.
The Boundary Layer Research VG kit was selected to obtain better short and soft field performance—which it delivers, plus the added safety enhancement of a lower Vmc and a practical increase of 166 pounds in zero fuel weight.
I installed the C&D combustion heater because the factory original Janitrol unit that was installed in the plane when it was purchased needed to be rebuilt, and even then it still would have a recurring AD with which I would have to comply. The new unit puts out more heat and is free of recurring inspections.
I installed an inflatable door seal primarily to correct the poor door-to-fuselage fit the Seneca came with, and to reduce cabin wind noise and keep the rain out.
Had I needed to replace the props, (it turned out that I was able to overhaul the existing units) I would have gone to the STC'd Hartzell three-blade propeller.
STCs I didn't go for include the Meryln Magic wastegate and several engine intercooler STCs, all of which promise cooler-running engines. Since I was not having any temperature problems with the engines and I live on the East Coast—thus limiting the amount of high and hot operations I would be engaged in—I felt I could not justify the expense.
I also passed on the Keith Products air conditioning system, mostly because of a single part required from Continental. That part, a pad that allows the air conditioning compressor to share the accessory pad with the alternator is only sold as part of a kit, and the kit cost in excess of eight thousand dollars. That made installing the Keith air conditioning kit economically impractical.
Some things I have yet to do? I'd like to install G&D acrylic window liners, and I am considering replacing the original Century III autopilot with a newer model from S-Tec. I am also considering GAMI injectors, which would yield more uniform EGTs and CHTs on the Continental TIO-360EB engines that power the Seneca II.
My modified 1975 Seneca II now performs as well or better than a brand-new Seneca V, and it does so for about 1/5th the cost.
Michael Leighton is a 3,100 + CFIIMEI/ATP as well as an A&P mechanic and former FAA Accident Prevention Counselor. He operates an air charter company in South Florida. You can reach him via e-mail at .

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