Airtest — Piper Seneca

Standard equipment also encompasses quieter three-bladed propellers with synchrophasers and polished spinners (which, although lovely, have their disadvantages; ask my daughter Lucy, whose self-appointed job is polishing ours). Heavy-duty brakes and tyres are also fitted, as is full de-icing, permitting flight into known icing conditions. This includes pneumatic leading-edge boots on all flying surfaces, electric prop mats and a heated windscreen panel.

The passengers continue to benefit from the 124cm wide fuselage, one of the roomiest in the business. This has a PA-28 style overwing door for the front seaters and enormous double doors aft of the left wing root providing easy entry for the four cabin passengers. The face-to-face club seating interior has been restyled and ‘quietized’ (ugh!) with suede headliner and leather upholstery. Shoulder harnesses and headrests equip all the quickly removable individual leather-covered armchairs. The pilots’ comfortable seats are also comprehensively adjustable, with variable pneumatic lumbar supports.

Retained features of the earlier Senecas include electric flaps, which superseded the original lever-operated units during the Mark II’s evolution. So did the current 24-volt electrics, which now use more powerful 90-amp alternators. Also preserved are the smooth, turbocharged six-cylinder Continental TSIO-360 engines. Their counter-rotation eliminates takeoff torque and ensures there is no ‘critical’ engine in the event of failure.

Australian Aviation May 1996

Senecas have always had good takeoff performance, and this Mark IV is no exception. In the air the Seneca IV is easy to fly, and performs every bit as well as its predecessors.

I am delighted to see that, while Piper’s stylists have slightly pared down the side windows’ lines, they have retained the one-piece windscreen and resisted the temptation to cut down its top as much as they have on the Archer II. (Although such a visibility reduction might not be so bad in this aeroplane as it would more frequently be used for IFR flight). Tinted Plexiglas is now standard, with integral pleated window blinds.

The Seneca’s capacity is exemplary but, while its limiting weights have been improved over the years, you still have to be careful not to overload it. Our test aircraft weighed in at a fairly representative 1511kg, so full fuel tanks (484 litres, or 349kg) limit its available load to 293kg, or a maximum of two light males and two female occupants with headsets. That is without luggage, nav bags, or even any documentation, which effectively makes this Seneca a comfortable long-range three-person aeroplane if you want to take suitcases of anything like the weight my wife packs. And then you must be sure to burn 168 litres of fuel (an hour and a half’s flying at 75% power) before being within the 2047kg maximum landing weight.

This is also the maximum zero fuel weight, enabling carriage of six good-sized occupants with 50kg of baggage, but limiting the fuel load to 150 litres, or just over an hour to empty tanks at 75% power. And, curiously, empty tanks is what you would have to land with, since 2047kg remains the landing weight limit! The message is clear. This aeroplane will carry a good load, but you must pay attention to your weight on any flight other than when solo. Optional certification is available at a reduced maximum of 1999kg to save navigation charges, but this further reduces available load by 156kg.

I flew with 400 litres of fuel aboard, making our weight around 1978kg, or 92% of maximum. Starting the cold engines using the now standard electric primers was simplicity itself, as was taxiing, although the nose wheel steering is somewhat heavy, with a noticeable lag between input and effect, which can result in a weaving progress until you get used to it.

Also slightly laborious is the need for careful engine handling. Maximum takeoff boost is forty inches, but these economy model Continentals have simple fixed wastegate turbochargers so their throttles should only be opened slowly, and with care, to rather less than that. This is achieved at little more than half throttle. As speed increases, so does the manifold pressure, and the throttles may have to be eased back to prevent overboosting. Warning annunciator lights illuminate if the limit is approached, and relief valves operate at 42 inches. Given time, Piper may introduce an improved system.

Senecas have always had good takeoff performance, and this Mark IV is no exception. We broke ground in perhaps three hundred metres, the gear came up in five seconds, and we throttled back and reduced rpm to 2600 (the 2800 takeoff setting has a five-minute limit). The most obvious external difference of the new-build Seneca IV compared to its forebears are the circular axisymmetric cowling inlets, a feature Piper has been introducing across its ‘new’ product range. The published two-engine climb rate is 1400ft/min, and we achieved nearly that at this lower power.

In the air the Seneca IV is easy to fly, and performs every bit as well as its predecessors, but it still handles like a London bus, with heavy controls and a ponderous roll rate, despite its differential Frise ailerons. Perhaps for the Mark V, Piper engineers will replace its old slab wing with the much-improved semi-tapered version used on their singles. This so transformed the PA-28 and PA-32 families, improving their overall performance as well as their handling, it seems a shame to constrain the PA-34 with this unrefined plank of a mainplane. More detailed drag reductions might also be beneficial, like undercarriage doors and fairings over the exposed flap and aileron hinges.

Nevertheless, the Seneca has a reasonable turn of speed, with Piper claiming a 75% cruise of 179kt (332km/h) TAS at 10,000ft, for a 640nm (1185km) range with 45 minutes reserves. Piper reckons that 33 inches and 2400 rpm generally give 160 to 175kt (295 to 325km/h). Throttling back will extend the range by nearly 50% without greatly affecting block times, so 45% power returns 143kt and over 900nm (1670km) with reserves. A table of representative power settings is printed conveniently on the pilot’s sun visor, and the enlarged engine gauges make it easy to set the published figures, but those fixed wastegates do mean you must take your time for the needles to stabilise. The propeller synchrophasers make prop synchronisation easy, though.

We flew our test Seneca at very close to its forward centre of gravity, so its stabilator forces were high throughout the flight, and especially in the landing flare. At least the rudder and stabilator anti-servo tabs increase their force in proportion to the ailerons, so it could be said to have good control harmony, and stability is strong in all axes. A tendency towards tail wagging in turbulence can now be countered with an optional yaw damper.

The Seneca has a long cabin and 45kg allowed in each of the nose and aft baggage areas. So strict attention should be paid to its loaded centre of gravity limits, despite the difficulties of interpreting the load and balance information in its Pilot’s Operating Handbook. Indeed, although the battery has been moved a few feet aft to reduce the problem, it is still possible to load a Seneca outside the safe envelope’s forward margin with full fuel and just two front seat occupants. That way lies a broken nose leg.

The Seneca’s low-speed manners are Piper-predictable. At our forward centre of gravity, it was barely possible to induce a stall at all, the horn sounding (clean) at 77kt (143km/h), with a gentle waffling break at 64kt (119km/h). Full (forty degrees) flap and extended gear reduced these figures to 65kt (120km/h) and 54kt (100km/h) with a mild pitch forward in considerable sink after a hefty heave on the yoke (although I suspect some position error, because Piper claims a 64kt (119km/h) full-flap stall). Recovery from a fully developed stall can take a couple of hundred feet.

Throttling back the right engine to a zero thrust of 12 inches manifold pressure induced an easily controlled yaw with moderate pedal pressure. Stabilising our speed at the blue line (best single-engine climb rate) of 92kt (170km/h), I timed a just adequate 250ft/min climb, which is what Piper claims at top weight and sea level. Keeping this boat afloat after an engine failure would require good pilot proficiency (in turn demanding constant practice). Single-engine service ceiling is 12,000ft.

Flying the approach is easy, the initial flap setting’s limit being a handy 140kt (260km/h) with a gear extension maximum of 130kt (241km/h) to aid speed reduction when required (max gear retraction speed is 108kt/200km/h). The full flap limit is 115kt (218km/h) and the slotted flaps’ full forty degrees provide a useful drag increase for short field work. However, to counter the heavy stick force in the flare and ensure the nose wheel remains off the ground at touchdown, many Seneca drivers recommend only 25 degrees of flap for landing. A final speed of 90kt (167km/h) for 85kt (158km/h) over the numbers worked well, providing good speed stability and forward visibility. Exercising my biceps in the flare led to a brief float and a gentle touchdown (although there is not much give in the Seneca undercarriage) before rolling to an easy halt in well under 800 metres.

The new Seneca IV has a two-year ‘spinner to tail’ limited warranty (so presumably the nose cone and forward baggage compartment are not covered!). The only competing piston twin in production is the more powerful (and much more expensive) Beech Baron (although Socata’s Tangara reincarnation of Grumman’s Cougar may soon give the Seneca a run for its money). Piper also reintroduced the Seminole during 1995, and made five that year.

With 4,500 Senecas already sold, earlier in 1995 Piper celebrated 40 years of light twin production since their 1955 Stinson-derived Apache. Piper delivered 99 aircraft in 1993 and 143 in 1994, they reached 179 sales last year, and already have more than 250 orders for 1996, so its future looks bright. Now that the Seneca is back on the market at under a half-million dollars, a new generation of twin owners has something to look forward to!