Airtest – Piper Seneca Ill

But that wasn’t enough for Piper; they decided to upgrade the Seneca line last year, the result being the beefier, more powerful-engined III now in Australia.

Vero Beach went for two main goals when considering the Three. Useful load and zero-fuel weight – now a standard useful load of 1898 lb and zero-fuel weight of 4470 lb, upping the old figure by almost 500 lb.

The upshot of these two figures is more flexibility, especially for operators who must carry heavy loads over relatively short distances.

To get the greater weight into the air, Piper went for an improved version of the Seneca II Continental TSIO-360 engine. Take-off power has been increased to 220 – 20 up on the II – by increasing redline revs to 2800 with a five-minute limit. Max. Continuous is 200 hp at 2600 rpm.

Despite relatively small horsepower, the Seneca Ill is slippery at altitude and can hold its own with bigger twins.

Other ‘ups’ include a modest increase in flap operating speed (from 109 to 113 knots) and an enhanced accelerate-stop distance.

In the office up front, the Seneca Ill has undergone a panel and instrument layout facelift compared to the earlier Two. Most significantly, the electrical switching has been relocated at the bottom of the main instrument panel.

Externally, the Seneca Ill differs but little from its elder sister apart from a panoramic-style one-piece windshield.

Under the skin, there has been some centre-section strengthening to take the increased weight and a popular one-colour paint job tops the lot.

All this adds up to a dramatic and satisfying picture. . .

Our evaluation team sat in shirtsleeve comfort amid a definitely quieter-than-normal environment, over a still-sunlit sea, with 10,000 feet of hot and unstable air between us and the Pacific.

We had been cleared by Sydney for air work in a 50-degree arc between radials. We wouldn’t have willingly budged from that slice of sky – to the north and south there were billowing thunderheads towering way up and a front was shifting silently but quickly from the south.

Filling tanks earlier at Bankstown we’d noted the flush type filling caps which, first made their appearance in the earlier Saratoga; and although one handles the Seneca Ill fuel system as one tank per side, there are actually two tanks in each wing with a bag-type tank between them, giving one 98 US gallons to play with.

Up there at transition height, there was time to set up typical cruise figures and see what the Seneca could do in terms of matching actual performance with book figures.

The long and short of our fiddling around was that Manual figures proved to be an understatement . . .

Although we only had two up – Ansett General Aviation’s Keith Robey, as unflappable and helpful as ever, and ourselves – the evaluation aircraft wasn’t all that much under a typical max gross/mid-cruise weight.

Setting up 33. 5 manifold pressure and 2500 rpm, we eventually got the aircraft trueing out at 180 knots; the Manual’s 75 per cent figure lists 31. 9 and 3300 rpm, giving a consumption figure of about 28 US gallons/hour. In ISA conditions one would expect 179 knots at midcruise weight; said the Book.

Fifty-five per cent power settings of 25. 5 and 2500 should have given us 159 knots of true airspeed. We applied slightly different settings (23/2350) and came up with 170 kts TAS after applying temperature correction of + 8.

So much for the Manual . . .

The line has come a long way since it was first conceived nearly ten years ago; we had time to digest Keith’s observation that Vero Beach’s first flying trials with the basic Cherokee Six airframe had been envisaged with the original single-engine configuration being boosted by additional powerplants – one in each wing, making the first-thought Seneca a tri-motor job!

It would have been different, to say the least. . .

The evaluation aircraft was fitted out with conference-style main cabin seating. The main cabin was as quiet as the cockpit and got full marks for appointments, which included six cabin fresh air vents.

Keith interrupted our semi-reverie by reminding us that your Seneca Ill is a most efficient and stable instrument platform, and beginning an ILS into Sydney airport coupled to the evaluation aircraft’s Edo Aire auto-pilot.

At all stages, the aircraft proved itself to be just that; all one had to do was occasionally push a button on the auto-pilot to initiate turns on command down the chute into Sydney.

This was where the 170 kts TAS crept in while descending at standard rate with 23/2350 set up.

Annunciator lights marked the various stages of our coupled ILS and made this type of approach a breeze.

Breaking off at 500 ft, we overflew Bankstown on our way out to some general handling in increasing chop as the front began making itself apparent.

Max. rate turns proved the Seneca Ill’s agility and response. Stalls in both conditions proved both arm-tiring and docile, with sink rate beginning right on the book figures of 67 and 64 knots. There was no wing drop apparent, although we did not investigate fully developed stalls at this stage.

Pitch changes during gear and flap extension proved noticeable but infinitely manageable.

And all the while we marvelled at that quiet cockpit and cabin decibel level. In fact, the only thing to impinge on the semi-silence was a whooshing whistle which flirted around the cockpit exterior while coming back down the speed range to a few knots above the stall onset point.

Asymmetries proved another point; one can easily trim out yaw after initial rudder take-up following an engine-out configuration intentional one-engine operating speed is Manualled at 85 kts IAS.

Turns into and away from the ‘dead’ engine are also part bf a confidence-building exercise which increases by the minute while handling the Seneca III.

OK, but what about your range? Comes the logical question. When answering this, one has to bear in mind that Piper’s Seneca Ill has never been billed as a true long-distance performer, rather a short/medium range heavy-hauler; and we mean heavy when considering horsepower and payload.

At mid-cruise weights, one could expect the following figures:

At 75 per cent power, 10,000 ft, standard fuel, at optimum height, 462 n. m. with optional fuel added, 665 n. m. At 65 per cent power, 550/ 785 n. m. At 55 per cent, 630/920. At 45 per cent, 670/990.

At 10,000 ft, which gives a more direct picture:

At 75 per cent, 450/640 n. m. , with book cruise TAS of 179 kts. At 65 per cent, 535/760 n. m. , 175 knots. At 55 per cent, 610/860 n. m. , 159 kts. And at 45 per cent, 632/900 n. m. , 143 knots.

Cruise speed at optimum height – where the real value lies and one has oxygen available give better speeds. At 75 per cent 193 kts TAS; at 65 per cent 191 kts; at 55 per cent 180 TAS and at 45 per cent you can still hike along at 168 TAS.

The Seneca III’s service ceiling has been approved at a full 25,000 ft.

Getting the aircraft into the air and on its way up to operating height is routine; setting up 2800 rpm and a whisker under 40 inches of manifold pressure is the standard take-off drill.

An over-boost light shows on the annunciator panel at 39. 8 just to remind you to watch power on take-off. Allowing stabilisation between 30 and 35 ins during take-off power application is a good investment.

Contra-rotating twin-blade Hartzells take care of all but noticeable swing during the unstick run, and the Seneca Ill exhibits a ready, precise response to control application, coming off the ground cleanly (in our case at 80 on the clock) and climbing out at 92 indicated.

En route climb was set up during our flight at 102 kts IAS; we eventually. Settled for 108 IAS with 32/2500 showing.

Your Seneca appreciates a normal approach at around the higher side of 90 knots. On a full-flap (40 degrees) approach, with a short-field touch in mind, it is like 82 on the clock.

AUSTRALIAN AVIATION found the Seneca a pleasant surprise, and a worthy successor to the older II we evaluated in 1976 according to our logbook.

It slots neatly into a space reserved for specialised passenger/freight operators who have a requirement for executive short-medium haul work, and the private owner who needs tractability, and long legs when needed (and payload allows).

Typical Cherokee Six wide-door capability and quick-change flexibility in the main cabin means a lot in terms of versatility. Piper has never been equalled in providing easy and very real access to the Six’s roomy cabin.

With a price tag of – on our evaluation aircraft – $220,500, the Seneca 111, backed up by Australia’s Piper service, should prove popular among its specialised customer field, and perhaps an ultimate stepping-stone to Piper’s Aerostar line for the person who wants rugged yet economical operation in terms of that nagging weight/payload/range equation.