|Piper PA-44-180 Seminole: the Twin Teaching Machine|
|Written by Bill Cox|
Dedicated fans of twin-engine airplanes are sometimes hard-pressed to justify their passion. Safety statistics suggest most twins aren’t any safer than singles, despite the alleged redundancy of the second engine.
These days, twins aren’t necessarily any faster or more comfortable than singles, either, with a few notable exceptions. Back in the late ‘70s and early ‘80s, there was a veritable plethora (is there any other kind?) of piston twins available–something like two-dozen different models. These ranged from stretched, lengthened, me-too, multi-motor versions of popular singles to turbocharged and pressurized super twins, the latter capable of blazing along at 250 knots or more with eight folks enjoying the ride in back.
The leader of the pack, Piper’s Aerostar 700P, was the fastest piston airplane in the world. Today, the production Aerostar twin is but a memory, and the quickest production piston product is a single–the Columbia 400, some 25 knots slower. (Aerostar owners tend to be fanatical supporters of the type, however, and Aerostar Aircraft of Coeur d’ Alene, Idaho is still very much in business performing conversions and maintenance.)
What was once a burgeoning twin market has shrunk to only four models: the Beech 58 Baron, the Diamond Twin Star, and Piper’s Seneca V and Seminole. (The upcoming Adam A500 will expand that class to five entries.) In typical Beech fashion, the $1.2 million, six-seat Baron represents the top of the class, with the best climb and normally-aspirated cruise performance, though the Baron’s narrow Bonanza cabin limits space in the critical cross section dimension.
Diamond Aircraft’s Twin Star is the newest entrant on the market. It is an airplane intended as both a personal transport, and multi-engine trainer. It features a pair of Thielert diesel engines, electronic FADEC control and standard turbocharging at low altitude. Handling qualities are excellent, and the airplane is slowly making inroads into the general aviation market.
The turbocharged Piper Seneca V offers the best speed in the class–just over 200 knots. It provides all this, plus the most comfortable cabin and better short field numbers, all for for a little over half the money. The current PA-34-220T represents three-and-a-half decades of evolution of the basic Seneca design. With its big cockpit and relatively low operating costs, the airplane remains popular with operators of small companies, charter services and private individuals alike.
Then, there’s the Seminole. From its inception in 1979, Piper’s PA-44 has become, perhaps, the definitive general aviation multi-engine trainer. True, Beech scaled up the basic Sierra to produce the Duchess and sold nearly 450 of the little devils, relying heavily on sales to the old Beech Aero Centers. Grumman American built over 100 of its clean-sheet Cougars, an original airplane reminiscent of nothing that had gone before.
Cessna, long the leader in single-engine flight training, elected not to compete for the multi-engine training dollar. The Wichita company’s 303 Crusader was originally planned to be a light-light multi trainer, but the type was reconfigured to a turbocharged, semi-cabin class machine, intended to compete with the Seneca. The Crusader was discontinued in 1984 after only three years of production.
Allowing for some fits and starts, Piper has kept the Seminole alive and selling for nearly 30 years. All the other comparable trainers are now long since out of production. As the new Diamond DA42 Twin Star becomes popular in the twin market, it will undoubtedly siphon away some of the Seminole’s sales. (Ironically, some instructors claim the DA42’s FADEC-controlled engines are TOO easy to manage in the event of a failure.)
Today, New Piper sells about 30 Seminoles a year, many of them to institutional flight training schools. These include such established aviation training departments as Embry Riddle, Purdue University, Flight Safety and the University of North Dakota.
UND, located in Grand Forks, North Dakota, is one of the most active and best-known aviation universities in America. The school offers six different majors in two degree programs. With over 1000 students in training at any given time, its Seminoles are among the busiest in the nation.
The school operates about 80 aircraft in its fixed-wing programs–nearly all of them Pipers–primarily Warriors, Arrows and Seminoles. The twin-engine Seminole obviously serves as the step-up airplane. Students earn their multi-engine rating and gain an insight into the world of charter with the PA-44-180.
With only 180 hp per side, the Seminole isn’t exactly a high performance twin, but UND finds the type near-perfect for the school’s training mission. Power isn’t big, but neither is operating economics, and that’s a major factor for any flight school–institutional or private.
Another of the Seminole’s strong suits for training is its low student intimidation factor. Piper has long been famous for turning out excellent teaching machines, from the original Cub to the Colt, the Cherokee 140, the Twin Comanche and the Tomahawk. There’s no question the Seminole is a significantly larger airplane than either of the other two Piper trainers – it features three feet more wing, a three-foot fuselage stretch and stands two feet taller – but the overall look and design are comfortable and familiar.
Just as the first Seneca was basically a twin-engine Cherokee Six, the Seminole was planned as a multi-engine Arrow, inheriting the latter’s gentle flight characteristics and docile handling. Pilots stepping up from the Warrior and Arrow will feel right at home in the PA-44’s cockpit. Piper did everything possible to make its three trainer aircraft as similar as possible in cabin configuration. The interiors are comparable, with a comfortable front office measuring about 42 inches across–roughly the same as the Beech 58 Baron’s cabin.
The Seminole’s panel layout is as consistent as possible with those of the two single-engine Pipers, considering the differences in function and performance. At UND, an aspiring professional pilot can transition from fixed gear to retractable to multi-engine with minimum changes in the cockpit.
The Seminole basically sports the Arrow cabin and airfoil and a pair of 180 hp, carbureted Lycomings in place of the Arrow’s single, 200 hp, injected Lycoming. True, the Seminole grosses almost 1000 pounds more than an Arrow, and there’s no question it has a very different control feel, but at least the environment remains friendly and familiar to pilots stepping up from the Arrow.
According to Piper specs, a typical Seminole–fueled with 108 gallons of 100 octane–should offer about 600 pounds of payload. While that’s not four folks worth, the deficiency may be irrelevant in an airplane that will spend most of its time with only a student and instructor up front, and perhaps a ride-along student in back to laugh at his buddy’s mistakes. One interesting feature of the Seminole is a huge CG envelope, not that the airplane needs it. The PA-44 can fly away with its load distributed pretty much any way you can imagine.
The T-tail is a carryover from the days when Piper thought it would be stylish to mount a tall horizontal stabilator on its entire line. In fact, the company nearly did exactly that until they realized that T-tails weren’t suited to every airplane. The Seminole is currently the only Piper with a T-tail, mounted up out of the wash off the props, so it’s less susceptible to asymmetric power changes.
If carburetion isn’t as efficient as fuel injection, it’s also not as expensive, quirky or susceptible to hot start problems. Such economic and operational simplicity can work to your benefit in a trainer with a student in the left seat.
With both engines running true, that student isn’t liable to have much trouble with handling during takeoff, either. The Seminole’s performance is considerably different from that of any Arrow, but all the changes are for the better. At 3800 pounds gross with 360 hp under the cowls, power loading is only 10.6 pounds/hp, and acceleration during takeoff reflects the difference. Similarly, climb checks in at better than 1300 fpm, and the PA-44 ascends as if mounted on motorized rails.
Of course, students training for the multi rating can expect to lose engines on a regular basis, and the Seminole’s mills are mounted as far inboard as possible to help mitigate that problem. The twin trainer also features counter-rotating props that minimize the challenge of single-engine operation by turning inboard. The left Lycoming rotates the prop in the standard clockwise direction (to the right), and the starboard engine turns its prop counter-clockwise (to the left). Lycoming designates the left-turning engine with an L out front–LO-360-A1H6.
This eliminates the old “critical engine” problem, and makes flying the Seminole a fairly straightforward process, no matter how many engines are on line. It also reduces Vmc well below the airplane’s dirty stall speed, making Vmc management unusually simple.
It’s important to remember, however, that actually caging one engine results in a dramatic reduction in climb performance and service ceiling. In the Seminole’s case, climb drops to 212 fpm and service ceiling is reduced to a density altitude of 3800 feet. For that reason, most single-engine training is simulated with zero thrust rather than with a prop actually feathered.
Handling is characteristically Piper-like, extremely gentle with no bad manners. Maneuvering is easy, and the controls are well-harmonized. The T-tail minimizes any pitch alteration associated with a power change, and stalls in any configuration don’t present any special challenge. In other words, the airplane’s design allows the student to concentrate exclusively on learning to fly a twin.
Cruise performance is nowhere near that of other twins in the class, but neither is it a source of embarrassment in view of the horsepower. Fortunately, cruise isn’t critical in a multi-engine trainer. The Seminole can score an easy 160 knots on 18 gph. With a full service of 108 gallons, plan on stopping every 4.5 hours, worth just over 720 nm at high cruise in no wind conditions.
Landings shouldn’t be too difficult for pilots who can simply walk and breath at the same time. Indeed, you can use most of the same approach numbers you’d employ in an Arrow, 90 knots on downwind, 80 knots on base and 75 knots on final. Flaps extend to a full 40 degrees, and the Seminole manifests very little pitch change with flap deployment. It’s easy to judge flare height, as the airplane bleeds off speed predictably in preparation for touchdown.
Piper knows a thing or three about building twins, and the company went out of its way to design the Seminole for easy maintainability. The unusual hinged nose cone allows convenient service on avionics power supplies, the electro/hydraulic gear is a scaled-up version of Piper’s bulletproof Arrow system and mechanics generally give the airplane high marks for ease of maintenance.
While it’s true twins don’t command nearly the market they used to, there is a continuing demand for the type among pilots who demand redundant power to go with their redundant navcoms. Piper’s talented Seminole may be the class’s entry-level machine, but it continues to offer perhaps the best choice for a new generation of pilots hoping for a career in aviation.