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contact :
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Pilot
report - Piper Seneca series
[Reprinted from Fliteguide / Imperial Aviation]
Piper's Seneca is the archetypal light twin. This
lofty achievement is shared by one other - Beechcraft's long-enduring
Baron - and whilst between them they account for nearly one hundred
percent of the current new twin market, they have occupied
diametrically opposite ends of the price spectrum.
The Seneca is about as conventional as twins get
which is odd given the model's whacky beginnings. It was during the
early sixties that light-twin safety aspects were the focus of
unwelcome FAA attention. Too many twins had been killing their
students and instructors during assymetric training. Piper's PA-30
Twin Comanche had attracted a particularly bad reputation. So much so
that Piper eventually fitted counter-rotating propellors, re-naming
the aeroplane the PA-39 C/R. Cessna had already launched their 337
push-pull in an effort to solve the problem.
In 1965, Piper decided to lace two 115hp
Lycomings onto the wings of their original prototype Cherokee Six.
This may seem to have been an anathema to Piper given their low-rent
position in the market place and many wondered about the rationale
behind such a layout. The 'Cherokee' retained its 250hp engine in the
nose. Flight testing proved the obvious - the three-engine layout had
little merit, especially as the wing engines couldn't be feathered. It
was back to the drawing board and Piper then had the brilliant idea of
removing the centre engine and calling it the 'twin-Six' using two
180hp O-360 Lycomings. A second prototype was built with retractable
gear and a lengthened tail and the production version, launched in
1972, was given 200 horses a side and counter-rotating props like the
C/R Twin Comanche.
Early Seneca's, whilst fulfilling Pug Piper's
edict of keep 'em cheap, keep 'em selling, were short on payload, and
had an unimpressive single-engine performance. The adaption of the
basic Cherokee Six structure only served to keep costs low - handling,
was compromised by a rudder/aileron interconnect which served to keep
the 'dead-engine' wing high using only rudder input. The controls were
thus extremely heavy for a light twin and steering on the ground was
also ponderous. In 1973, Piper upped the max gross weight by 200lbs
which had the predictable effect of dramatically reducing its engine-out
ceiling even further, which at 3,650ft is the lowest of any post-sixties
production light-twin ever made.
The arrival of the Seneca II in 1975 was a mighty
breath of fresh air. At the II's heart were a pair of turbocharged
Continental TSIO-360s, each rated at 200hp. The engines benefitted
from from fixed-wastegate Rajay turbos and later 'EB' versions would
go to a TBO of 1,800 hours. The effect was dramatic. Payload went up
by a further 200lbs, single engine ceiling rose to a heady
13,800 feet
and cruise speed leapt from the low one-sixty's to 177 knots at
regular altitudes and 191 at
25,000 feet
. Fuel capacity was also increased from
95 gallons
useable to an optional 123. Bombarded by handling complaints, Piper
also included balanced ailerons, a larger horizontal tail and a new
rudder anti-servo tab to help if an engine quit. The Seneca II was
also smoother to ride in.
In 1981 Piper gave the II a facelift and a added
three-blade props and 20hp extra per side, calling their new, improved
model the Seneca III. Again there was a payload and speed increase.
The III remained in production through the company's bankruptcy years
during the early nineties. Production, from 276 aeroplanes in 1981
dropped steadily to
39 in
1987 and to a mere 10 airframes in 1993. The New Piper Company bravely
continued and launched the Seneca IV in 1994.
At this point it worth remembering a major if
subtle change of Piper marketing dogma that has taken place following
the company's emergence from chapter 21 bankruptcy. With the gold-rush
era of light aircraft production well and truly over, Piper decided it
needed to change its el-cheapo image. The few light-twin buyers around
today are less concerned with apron-one-upmanship satisfied by the
number of engines attached to their airframe. With the advance of
technology, particularly in navigation and the demands of an ever more
sophisticated airspace, buyers want greater weather capability, safer
cockpits and a more comfortable cabin environment. Throughout the 28
years of Seneca production the gap between Piper's crimpolene-era
interiors and today's leather and veneer fittings is huge. The Seneca
V is a vastly different aeroplane to the Seneca I and it's here that's
found the logic between improving the IV and launching the V. Light
twins are no longer an essential upgrade from a single, but are sold
as all-weather business Fliteguide, much like a Learjet, Citation or
Challenger.
By definition, it's the details that count and
it's here that the V is a significant advance. Piper has made a silk
purse out of a sow's ear - it has gone significantly upmarket.
In the cockpit Piper has retained the aluminium-finish
one-piece panel beloved of airliner makers. The most immediately
noticeable changes are the reduction in windscreen depth allowing
placement of the engine start switches, magnetos and booster pump
rockers to the cabin roof. There's little practical value in this, but
it does separate an important switching function. Piper reckon it'll
make you feel like you've climbed inside a luxury automobile... I
think not... rather It'll make you feel you've climbed into a business
jet - a far more attractive proposition. This juggling with switches
has a downside which is a reduction in forward visibility.
Nevertheless as a subjective improvement it's fine. Indeed Seneca's
have never been great aeroplanes from which to see the world go by,
the engines dominate the pilots peripheral vision, severly hampering
any view to the side and downwards. The only mistake Piper has made is
to then raise the central portion of the panel to accommodate a row of
annunciator lights, thus further reducing an already restricted view
outwards. It's not as if the panel itself is short of room - there's
acres of it and the raised glare panel leads to one eye directed
forwards over the nose and the other struggling to focus between the
two. As an IF platform, its superb, but it doesn't encourage keeping a
VFR watch.
The large-face engine gauges have been thrown out
at long last, replaced by minaturised business-jet type dials. These
may be more difficult to get used to, but tidily seperate the primary
instruments from secondary gauges. Piper has installed a grandly named
Self Check In-line Flight Instrument and Monitoring System. This piece
of micro-electronic wizzardry seems at first to be another pseudo-big
aeroplane gadget designed to convince pilots that light aircraft are
approaching the required skill levels of company jets. However, it has
some convenient features. The system enables the pilot to adjust rpm
and manifold pressure to accurate numerical settings. The value of
this facility in a light
twin is doubtful, for no other reason than
current piston-engine technology isn't sufficiently sensitive to
require such accurate power settings. Moreover, the Seneca V's
throttle levers, even with the friction off, are too stiff and clumsy
to match even using the rpm gauge. For those that enjoy fiddling and
achieving absoulte precision, this facility will keep them amused for
several minutes once established in the cruise.
Of greater value is the fuel computer, and
Turbine Inlet Temperature monitor all combined in the same unit. This
will give a fuel and time remaining solution and will signal a warning
if the TIT exceeds its preset value. The system will also give you an
OAT reading and will measure the temperature in the cabin too. A
glaring omission, and one that would be a real asset to any safety and
cost conscious owner, is an electronic engine monitoring facility. At
an installed cost of around US$2,000 it should be fitted as standard
in any brand new twin. Nevertheless, the Seneca V has a high level of
standard equipment including a number of other useful gadgets and
switchgear. A remote VHF radio rocker switch has been included so that
pilots can light up a single com to ask for start clearance and
communicate with others without having to punch the master avionics
switch. There's also a Flitecom digital recorder to 'tape' the last 30
seconds of a radio transmission, this prevents asking ATC to repeat
their instruction if part of a clearance has been missed.
Continental IO-360 engines are usually easy to
start and the Seneca V's Turbocharged RB versions are no exception.
Reaching up, pumping some fuel into the manifold, then leaving the
pumps in the 'low boost' position and thumbing the starter has the
engines rumbling into life in no time. Punching the electronic
monitoring system's self test button allows it to run through most of
the electronic circuits and flash an annunciator warning if anything
hasn't come on line.
The throttle levers are stiff and so is the
nosewheel steering - a legacy of past Seneca models. The run-up is
done at a high 2,300 rpm so the propellors cycle very quickly and
snarl down to 1500rpm to check the feathering function. We line up.
Seneca pilots are familiar with carefully monitoring manifold pressure
on takeoff. Earlier turbo Seneca's used a simple bypass valve and an
overboost relief valve, eliminating the need for a complicated
automatic wastegate. This demanded more attention from pilots on
takeoff in order to avoid an overboost. There's no such tiresome
chores on the Seneca V. Now fitted with an auto wastegate, the
throttles can be firewalled without risk of blowing the turbos,
removing a major distraction from the takeoff phase. Piper has also
included intercoolers and at long last pressurised magnetos.
There's no requirement for flap on takeoff and as
on the earlier IV, the V continues with the electronic flap actuators.
The Seneca needs positive back pressure to unstick and at 65 knots,
the nose comes up smartly in reponse to firm control input. Aiming for
an initial 88 knots blue line speed, we put the gear away and
accelerate towards a best cruise climb combination of 110.
Seneca's have always required considerable trim
input when altering speed or changing the airframe configuration and
the V is no exception. Pilots won't be stepping out of their Seneca
V's flush with a feeling of returning from a fighter interception
sortie. the controls are firm, both in pitch and roll, encouraging as
quick a transition to cruise levels as possible and then flicking on
the KFC 150 autopilot. The Seneca is an A to B aeroplane and this it
does very nicely. Piper are aware of the aeroplane's popularity
amongst charter operators and know that many customers will use their
aircraft in an IFR environment. Consequently Seneca's arrive fat with
a useful Bendix/King package including dual Nav/comms with glideslopes
and a KLN 90B GPS.
Whilst the Seneca doesn't exhibit fighter-like
control response, its handling with an engine out is extremely
friendly with a fairly light pedal force required to keep the ball in
the middle and this can trimmed out very quickly. The extra 20hp per
side has given the single-engine ceiling a boost from
13,800 feet
to
16,500 feet
. Whilst Piper has experimented with its taper wing, the company has
elected to stay with the traditional thick-chord wing so beloved of
early Cherokee's - this further gives the aircraft benign stalling
characteristics. Any twin is likely to bite hard when entering VMCA -
the speed at which directional control is lost on one engine. The
Seneca is a great deal kinder in this condition than a Baron or Cessna
310. Firstly, its counter-rotating propellors mean there is no
critical engine and secondly its stall speed of 60 knots is close to
its VMCA of 66 knots. However, few pilots will be exploring this
regime outside of a training environment, but its good to know that
the Seneca, in terms of light-twin single-engine surprises, needs to
be 'in-extremis' before going feet-up after an engine failure. Blue
line speed - best single engine climb speed - is 88 knots to which the
aircraft accelerates quickly after lift off.
Piper's book figures for cruise speed are pretty
accurate. The aircraft needs to fly at
18,500 feet
to reach its maximum cruise of 190 knots. It's doubtful many operators
will go this high however as its occupants will need oxygen - never a
favourite for both pilots and passengers. Setting the manifold
pressure to
30 inches
and 2,400 rpm at
7,500 feet
will produce a repectable 175 knots. With
122 gallons
of useable fuel, the Seneca V will go Johannesburg-Cape Town with
relative ease and arrive with a good 45-minute reserve. To do this
will need some compromise between fuel and passengers. With maximum
fuel there's
655 lbs
available for occupants and baggage - that translates to three 170-pounders
and overnight baggage. Filling the cabin reduces the fuel allowance to
50 gallons
- enough for a tanks dry,
18 gallons
per hour, long-range cruise endurance of two and three quarter hours -
enough to do Durban from Johannesburg with an IFR reserve. It would be
good to bear in mind that fuel flow changes considerably with power
setting, so a high speed cruise of 180-plus knots will dramatically
increase consumption from 18 gph to 28gph and in this case a passenger
may have to be offloaded to stay within the weight and balance and
fuel reserve requirements for this sector.
These figures are flexible enough for a private
owner, but spring some limitations on charter operators in Africa.
Typical charter flights for light twins often route across border to
Victoria Falls, Harare and the Okovango delta - many flights departing
with four or more passengers and luggage. If you see a Lanseria - Maun
Seneca taxying out with six adult occupants, you'll know it's about
150 lbs
overweight.
Seneca's need a little getting used to in the
landing configuration. Piper moved away from the low-tech but no-nonsense
'hand-brake' flap lever when they launched the IV, replacing it with a
well-positioned electric system. Electric trim comes as standard and
thumbing the switch on top of the control column easily compensates
for approach trim changes. Those who know Seneca's will be familiar
with the last rearwards and upwards travel of the column during the
flare.
At the correct threshold speed this curious
control input will tidily arrest the sink rate. Those unfamiliar with
this minor quirk might be surprised as the aircraft settles down
firmly onto the runway having seemingly run out of rearwards column
movement. A good instructor and plenty of circuits will sort this out
for new Seneca pilots, but it's not unfamiliar to see this type of
aircraft sitting in the airframe repair shop having new gear mounting
brackets fitted and in some cases spar-damage rectification.
Nevertheless, turbocharged Seneca's have well earned reputations for
getting into and out of very short strips and if this isn't enough,
There's a Robertson STOL kit available.
From an early point in the aeroplane's career, Piper installed a club
seating arrangement and the aircraft has always benefitted from a
large rear passenger door. These features have made the aircraft
especially popular. The interior of the V is a dramatic improvement
over earlier models. Leather and soft fabrics have been used
extensively in pushing the aeroplane's appeal upmarket. Concertina
window blinds have been crafted to slide up and down within their own
moulded fittings and Piper has even offered the choice of removing one
of the central row seats and replacing it with a wood-finish console
and pull-out table. Indeed, knowing that many Seneca customers are
private buyers, the option list for the rear even includes a sound
system and video installation. A 45,000 BTU combustion heater can be
controlled from a panel in the passenger cabin to throw heat out of
six floor-mounted vents.
The Seneca design has played a key role in Piper's continued if
sometimes precarious struggle to survive. Whilst basic handling has
remained pretty much unchanged, performance has steadily improved in
response to customer design. The latest Seneca V is above all an
indication that the company's marketing thrust has moved smoothly from
charter operator to personal owner and it's, here the aircraft has
demonstrated its greatest improvements - cabin and cockpit environment.
Whilst the numbers are down from the heady seventies, the aircraft is
bound to remain the world's best selling light twin.
contact :
celaluzar@yahoo.com
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1973 PIPER
SENECA II PA 34-200
