Airplane Intel Podcast Show Notes


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episode 25 show notes

This week, we’re comparing the Piper PA-30 Twin Comanche to the Piper PA-34 Seneca thanks to a listener request. Then we talk about an update to mandatory service bulletin 05-8B and where to find the latest ADS-B out map from the FAA. Plus, aircraft ownership news, the tip of the week and a ton of your feedback about experimental aircraft.


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Weighing Your Options: Piper twin comanche vs. piper seneca

If you’re looking for a reliable piston twin that is suitable for both business and personal travel, Piper has you covered with its line of light twins. Today’ we’re focusing on the PA-30 Twin Comanche and PA-34 Seneca. Now these two airplanes aren’t typically compared side-by-side... About the only things they have in common are two engines. However, some of you out there wanted to learn more about the both of these airplanes – and rightfully so because each has distinct pros and cons. And it’s not uncommon for someone in the light twin market to consider both aircraft at some point through their process of researching prospective aircraft.

Let’s start with the Twin Comanche, a 4-6 place light twin designed to replace the Piper Apache line. The Twin Comanche first flew in 1963 with about 2,200 produced until production stopped in 1972. As you might’ve guessed, the Twin Comanche is a twin-engine version of the Piper’s popular single-engine aircraft the PA-24 Comanche, which we covered in episode 20 with Dean Showalter.  The Twin Comanche was first designated the PA-30 with several variants that eventually led to the PA-39 Twin Comanche C/R. The C/R stands for counter-rotating, which means the props spin in opposite directions. More on that later.

The Twin Comanche really isn’t a direct competitor with the Seneca. It’s more in line with the Beech Travel Air and Grumman GA-7 Cougar. Later models competed more with earlier Cessna 310s and Barons.

The original PA-30 Twin Comanche was equipped with two fuel injected IO-320-B1A engine producing about 160 horsepower per side with a 2000 hour TBO. These are four cylinder, horizontally opposed, direct drive engines. As most of you know, the 320 series engines are known for their reliability and relatively low operating costs – but surprisingly, these fuel-injected versions bring a lot of performance with them - somewhere in the neighborhood of 170 knots burning about 17 gallons per hour. The original aircraft is also a four-place airplane and can be easily distinguished from later models thanks to its 2 side windows. Believe it or not, the earlier models produced from 1963-1965 were available as bare-bone VFR day-only aircraft with a single vacuum pump. Better avionics and equipment were made available as an option, and can be IFR approved if equipped to Part 91 standards.

In 1965, the PA-30B was introduced. This airframe featured room for 6 and a third side window was added. The option list was greatly expanded to include wing tip tanks, which gave an extra 30 gallons fuel for a total about 120 gallons. STCs are available through Brittain Industries to equip earlier models with tip tanks as well.

But remember, these are early-to-mid 1960s airplanes; while many of the remaining airplanes have been modified, there are some aircraft with original panels still flying. According to AOPA, some of the issues to be mindful of with original panels are most of the toggle switches are identical and can be easily misidentified. Moreover, many of those panels have a shotgun instrument layout – the altimeter is in the bottom left corner and the DG is up where the attitude indicator normally lies.

Fortunately, many of the earlier model’s shortcomings were addressed in 1968 with the introduction of the PA-30C. With it came a new panel with a basic T instrument layout, new switches, added side panel for engine and magneto controls, and repositioned circuit breaker panel from inside the throttle quadrant to the right panel. Thanks to some engine adjustments such as the addition of beefier valves and valve guides, and better lubrication, the aircraft saw a few extra knots of cruise speed. Turbo normalized engines were also an option. There’s also an aftermarket option for a 200 horse power Lycoming.

In the early 1970s, The PA-30 became the PA-39 and featured counter-rotating propellers. This gives you the advantage of not having a critical engine, and reducing the yaw moment in the event of an engine-out situation, which for many light twins, losing the critical engine – the left engine – is a recipe for disaster. The PA-39 is available with both normally aspirated and turbocharged engines. The turbonormalized engines are the IO-320-C1A’s with Rayjay turbochargers. The turbo versions can be distinguished from normally aspirated engines in part to the vents on the sides of the engine nacelles. The Twin Comanche is equipped with a dual 12-volt DV electrical system with 50 amp generator. Main tanks can hold 30 gallons per side, with aux tanks in the outboard wings at 15 gallons per side. As I mentioned, the tip tanks add an additional 30 gallons. All in all, at a modest cruise setting, this is about a 5-hour airplane without tip tanks.

All variants have 160 horsepower, fuel injected engines mated to constant-speed props. Normally aspirated models have a gross weight of 3,600 pounds and the turbo version’s gross weight is 3,725 pounds. Useful load ranges from 1,300-1,393 pounds. Baggage capacity is about 250 pounds. Service ceiling ranges from 18,600 feet to FL250 on the turbo versions. Where the Twin Comanche falls short is in cabin comfort. Inside, cabin width is just 44 inches, and height is about 46 inches. Ingress and egress are also difficult with its single cabin door. It’s also a bit of a challenge to handle and it lands a bit flat and hard if speed and glide aren’t right.

On the other hand, the Piper Seneca has been in production since 1971. It has withstood the test of time as one of the last-remaining piston-powered twins still in production. And it has seen a lot of changes and improvements over the years. It’s a 6-place, light piston twin, and basically the multi-engine version of the Cherokee-Six. In fact, during initial testing, Piper placed two wing-mounted engines on a Cherokee-Six, testing the prototype with a total of three engines! But the first prototype Seneca’s weren’t Seneca’s at all – they were known as the Twin Six, with dual O-360 180 horsepower engines later designated the PA-34-180.

But the Seneca we all know today was first certified in 1971 and came standard with two 200 horsepower Lycoming IO-360-C1E6 engines. Actually, the right engine is the LIO-360 indicating a left-hand turning crankshaft, giving the airplane counter rotating props. It’s designated the Seneca I or more formally, the PA-34-200. It has a gross weight of 4,000 pounds with later models having a gross weight of 4,200 pounds.

The Seneca I had some handling issues. Piper fought back by introducing the new and improved Seneca II in 1975. The new airplane was equipped with turbocharged engines, namely the TSIO-360E engines, producing 200 horsepower a side. Turbocharging gave the airplane better performance for takeoff and climb as well as high-altitude cruising. It also allowed for another gross weight increase to 4,570 pounds. To tackle the handling complaints, Piper installed balanced ailerons, a stabiliator bob weight, and an anti-servo tab to the rudder. The Seneca II also featured some improvements to the cabin – namely the option for club seating.

In 1981, another version of the Seneca was introduced; you guessed it, the Seneca III. This time, engines were upgraded to 220 horsepower TCM TSIO-360-KB engines, which limited maximum horsepower output to five minutes. The Seneca III is easily distinguished from earlier models thanks to its one-piece windscreen. Moreover, the instrument panel was also updated and some later models featured a 28-volt electrical system and electric flaps. The increase in horsepower also brought another increase in gross weight, this time to 4,750 pounds.

In 1994, minor improvements were made to the Seneca, giving birth to the Seneca IV. Most notable, improved cabin and cockpit layout and streamlined engine cowlings for better performance.

Finally, the Seneca V came to be in 1996 and is still in production today. The aircraft has an all new cockpit design, including a number of switches relocated to an overhead panel. The engines were replaced with TSIO-360-RB engines which feature an intercooler. Gross weight remains at 4,750 pounds, but thanks to added equipment, the aircraft’s useful load is several hundred pounds less. The Seneca V also has options for de-ice equipment and air conditioning as well as flight instruments for the right seat. Depending on the year, you’ll find Seneca V’s with standard steam gauges, an Avidyne Entegra package, or Garmin G1000.

Some of the other nice features of the Piper Seneca is its wide cabin entrance door and of course roomy cabin. The cabin is about 49 inches wide, 42 inches high, and just over 8 feet long. Later models have a service ceiling of 25,000 feet, burning about 23-24 gallons per hour at 75% power. They’ll climb about 1,400 feet per minute and cruise in the neighborhood of the high 180s depending on power. With 128 gallons of fuel on later models, this gives you about 5 hours of endurance, or 800 miles with reserves.

Who is in the market for a light piston twin? Better yet, who is best suited for a light twin? Well, if you have been flying complex singles for some time and you’re ready to step up, a piston twin might be for you. You might even step up from a less complex airplane and go straight into a twin to build multi-engine time. Additionally, if you take your family or business associates on frequent short to medium range trips, you and your passengers will appreciate the added safety that two engines provide. Corporate operators and charter companies around the world have also found a lot of use for the Seneca. Either way, the light twin market is narrow – which is good for you because that means there’s a disproportionate relationship between supply and demand – bringing prices down making for good buys on both aircraft.

So, between the Twin Comanche and the Seneca, which is a better buy? That answer really lies in what your mission is and what your overall objectives are... With anything in life, there are tradeoffs. When compared side-by-side, the Twin Comanche is quieter and more efficient than its Seneca counterpart. But the Seneca is roomier, more modern, and parts are fairly easy to come by for all variants. Seneca’s also provide greater load carrying capability and performance compared to the relatively under-powered Twin Comanche. Moreover, Twin Comanche’s are aging, and there are limited numbers for sale. It probably goes without saying that a quality prebuy is a must on either airplane – especially when it comes to engine and airframe corrosion and AD compliance.  You don’t want any surprises during your first annual, which with a twin, could cost you. Also, both aircraft types are commonly used in flight schools. So you’ll want to make sure the aircraft didn’t get too beat up.

If you’re still unsure which aircraft is best for you, it’s a good idea to grab a copy the POH to see the performance numbers for the ways you intend to fly and operate the aircraft. You can get a lot of manuals for free on internet. It’s also a great idea to fly both aircraft to see which one you’re more comfortable with.