With new light twins coming on stream, you would be forgiven for thinking the writing is on the wall for the older ‘tin’ types. John Absolon had the opportunity to evaluate the venerable Piper Seminole and compare it to the new generations of twin trainer.
When I told a few of my flying mates that I was going to fly the Piper Seminole as part of a flight review, I received varying comments ranging from stories about their experience with the twin trainer during their training, to some quite derogatory names that had been attributed to the aircraft.
Love it or hate it, the truth of the matter is that the Seminole is a very capable and cost effective twin trainer that has endured in the training market for over 30 years in all parts of the world, including being used by one military operator. It has outlasted most of its competitors.
Currently there are only a handful of twin-engined light aircraft that are built predominantly for the twin IFR training role. These mainly consist of the Seminole and the Lycoming powered Diamond DA42-360 or DA42-NG diesel. The latter is also marketed as a four-seat personal twin and has been reviewed in Australian Flying in both its forms previously.
Although not as widely used, the Rotax powered Tecnam P2006T is also a capable twin trainer. The remainder of the twin training role around Australia is filled by older variants of Beechcraft twins as well as older Senecas and Seminoles.
The Piper PA-44-180 Seminole is really the only twin currently being built in the USA that is being marketed almost directly for the training role. Piper is still one of the most trusted brand names in general aviation with a range of aircraft from the single Warrior–designed mainly as an ab-initio trainer–to the turbo-prop Meridian personal or business aircraft.
The PA-44 Seminole started life back in 1978 as a four seat twin-engined aircraft built around the well proven PA-28 Cherokee and later Warrior fuselage. The single engine was replaced with a streamlined nose section while the wings were redesigned to mount twin Lycoming O-360 four cylinder engines. The wing plan-form retained the tapered outer panels that were introduced on the Warrior model of the PA-28.
Using essentially the aft fuselage of the Arrow IV, the Seminole also inherited the all-moving horizontal T-tail tailplane as well.
In the latest variants of the Seminole, Piper has installed twin Lycoming engines so that the propeller rotation is what is called counter-rotating; that is, each engine rotates in the opposite direction to the other.
This opposing rotation avoids one of the problems in handling single engine failures in a light twin: failure of the critical engine. The critical engine is the engine that, should it fail, will cause the biggest yawing effect on the aircraft.
If both engines rotate clockwise as in a normal Lycoming installation (as viewed from the rear), then the combined thrust line would be slightly offset to the right side of the aircraft’s centreline. Therefore, should the left engine fail, the yawing effect would be greater than if the right engine had failed and more rudder would be required to offset this yawing tendency.
By installing engines with opposite directions of rotation, the thrust lines can be kept closer to the aircraft’s centreline.
Lycoming manufactures the 180-horsepower O-360 engine that is fitted to the PA-44-180 Seminole in two variants that rotate in opposite directions. The right engine being a LO-360-E1A6D that rotates counter-clockwise as viewed from the rear. There is no gearbox required, just two different model engines and two different propellers to cater for the counter rotation.
An obvious heritage
Walking around the latest Seminole you can’t help but notice some of the ancestry derived from the Warrior single-engine trainer.
The Seminole has the same window and cabin arrangement as the Warrior, but it gets its T-tail from the Arrow IV. The all-moving horizontal stabilator has a near full span trim tab across the trailing edge. This tab is an anti-servo tab; that is, when the tailplane is deflected, say, upwards, the tab deflects further thereby tending to drive the tailplane back towards the neutral position.
This action reduces the tendency for the pilot to over-control in pitch because of the large effectiveness that an all-flying stabilator has over pitch authority.
The rudder, which is fitted with a large manually activated trim tab that is also an anti-servo tab, is also a little larger in area than its Warrior ancestor with the larger area required for directional adequate control should an engine failure occur. One advantage of such a large rudder and tab is that it decreases the Minimum Control Speed Airborne (VMCA) to be actually lower than the stall speed.
The trailing edge flaps are of the simple hinged design the same as the Warrior and are operated similarly by a mechanical system from the floor mounted handle; simple and reliable as proven for years in the Warrior design. Each wing flap section extends under the aft part of each engine nacelle so that no part of the flap is wasted by an intruding engine nacelle’s streamlined shape.
The Seminole sits atop a conventional retractable tricycle landing gear. The gear is hydraulically retracted with the hydraulic system being electrically powered. Raising the gear switch to UP powers the pump to supply pressure to raise the gear until it is retracted. Once the gear is up, the pressure is locked in the line to hold the gear retracted, there are no mechanical up-locks.
To lower the gear in an emergency situation, you only need to pull the Emergency Gear Extension knob on the instrument panel and the hydraulic pressure is released from the system and the gear will free fall and with the help of springs and gravity will lock in position.
To ensure that the nosewheel is fully lowered, there is small convex mirror on the inboard side of the left engine cowl so that the pilot can see the nosewheel when fully extended. The usual three green lights on the panel indicate when each landing gear leg is locked down.
To back up the indications and also to remind the pilot if he has forgotten to lower the gear, a warning horn will sound when the throttles are retarded to a low MAP.
The nosewheel is steered through the rudder pedals via a direct link with some spring balancing to balance any shock loadings, but to all intents and purposes, it is a direct link. The steering forces are quite light and with the toe-operated disc brakes, there is no problem in ground handling.
The retracted landing gear is covered by doors when retracted with the exception of the main gear tyres which remain exposed but with their outer surfaces lying flush with the underside of the wing. A small flush ‘hub cap’ can be fitted to further reduce drag when the gear is retracted but had been removed from the test aircraft.
Slightly offset to the right side of the nose of the Seminole is the powerful landing light. New Seminoles are fitted with a modern multiple LED combination unit the same as the one that had been fitted to the test aircraft after market.
Just above the landing light is the NACA-style air scoop for the cabin heater. This heater is a combustion heater that burns aircraft fuel to supply heated air to ducts under the cabin floor with outlets at each seat and the windscreen defrosting outlets. The exhaust of the combustion heater is a small pipe on the lower right side of the nose cone.
The fresh air that is distributed through the overhead grills in the cabin is ducted from a louvered air intake on the left side of the aft fuselage and boosted by an electrically powered blower.
The twin Lycoming four-cylinder engines develop 180 horsepower each and drive through Hartzell constant speed props. They are cooled via the customary twin air intakes either side of the prop but their outlet is controlled by mechanically operated cowl flaps on the under side of each nacelle.
Stored behind the firewall in each nacelle are the twin 205-litre fuel tanks that are filled through caps under access panels on the top of each nacelle.
The fuel selection controls labeled ON, OFF and X-FEED are located on the floor between the two front seats giving the pilot the ability to select the fuel ON or OFF for each engine and to transfer fuel from one side to the other in the event of an engine failure to use all the fuel remaining through the good engine.
Of course, in the unlikely event of an engine shutdown, it is paramount that the pilot should check the fuel selections using a checklist when transferring fuel to avoid running out of fuel for the good engine. Transferring fuel will also help to keep the aircraft laterally balanced with the asymmetric consumption of fuel.
Stepping into the Seminole was like getting back in touch with an old friend, and I was immediately familiar with Piper’s layout of controls; although most were somewhat more modern than the late 1960s Cherokee 140 that I had learnt to fly in.
The centre-mounted mechanical flap handle was still there but the coffee grinder style ceiling mounted elevator trim handle was gone.
Adjusting the seat forward was done by sliding the seat forward on the floor rails and locking it into position with a handle across the lower front of the seat.
With my longish legs, this left very little room for anybody that would want to sit in the back. It’s this rather limited back seat room that lends the Seminole to be mainly used as a multi-engine trainer.
The view forward is a little limited by the rather high instrument panel, the long nose profile and the lowish seating position. Also the seating position, when correctly adjusted, means that you are sitting just behind the wing leading edge, and with the broad-chord wing section and large engine nacelles mounted slightly forward and quite close to the fuselage sides, the view below and to the side is a little more restricted than I would have expected compared to the other light twins.
What was new was the instrumentation. Gone was the vacuum-powered artificial horizon and DG and in their place in this particular Seminole was a modern AviDyne Entegra EX5000 R7.0 EFIS system.
The left hand screen was configured as a Primary Flight Display (PFD) and the right hand screen as a Multi-Function Display (MFD) that displayed the relevant engine indications of Manifold Pressure, RPM, Oil temp and pressure, exhaust gas temperature (EGT) and CHT, fuel flow and quantity and the electrical system volts and load.
The MFD could also be used to display a map or a chart display if the appropriate data bases have been optioned and loaded.
These two large identical screens almost filled the panel along with a centrally-mounted stack of twin Garmin GNS 430 NV/COM/GPS avionics made this 30 year old design look like a modern aircraft designed to train tomorrow’s commercial pilots.
The twin Garmin GNS units were surmounted by the S-Tec autopilot control panel and the Garmin audio controls and a row of warning and caution lights alerting the pilot to the various systems’ statuses.
A standby ASI, attitude indicator and altimeter occupied the far left side of the panel in a vertical stack arrangement. To the right and low on the panel were the Garmin Transponder and a King ADF.
Piper advertises that the 2012 model of the Seminole is now fitted with the Garmin G500 EFIS, which consists of two smaller six-inch screens on the left side of the panel.
As this Garmin EFIS doesn’t have all the same MFD capabilities when it comes to engine indications, the usual round dial Manifold Pressure and RPM engine instruments sit between the EFIS and the avionics stack.
Mounted in the centre quadrant were the usual combinations of twin throttles, RPM and mixture levers. Below these were the carby heat levers and even further down were the cowl flap controls.
Between the seats and mounted in a small quadrant is the manual pitch trim wheel. This backs up the electric system which has an activation switch on the left hand yoke only
To the right of the elevator manual trim wheel is the manually-operated ‘hand brake’ style flap handle. Behind these controls is the rudder trim wheel and indicator.
I just found that activating these controls mounted on the floor was a little bit of a reach down for me requiring me to actually bend forward and down to get to them. Also, when flying the Seminole from the right seat, I had to move my left hand from the engine controls to operate the trims which could be a problem in an asymmetric situation because it would mean leaving the throttles unguarded.
It’s always a good idea to guard the engine controls when in an asymmetric condition to avoid the inadvertent reduction of the controls of the one good remaining engine; could be embarrassing!
The landing gear switch is located just to the left of the throttle quadrant with the associated three green indicator lights sitting side be side just above the switch.
The emergency landing gear knob is just beside the wheel-shaped gear switch. Raising the guard and pulling the emergency knob releases the hydraulic pressure from the system holding the gear up and allows the gear to free-fall into the down position.
The parking brake knob is located directly under the left hand yoke and as a result could easily be obscured from view of the left hand seat pilot. I would prefer to have it in clearer view.
These are all minor points of what is a rather well laid out panel, certainly much better than the ‘steam’–sorry–vacuum-driven affair that I had experienced the last time I flew a Piper trainer.
Cabin ventilation is provided by two overhead fresh air outlet grills. On the ground, taxiing with the door slightly ajar or by opening the direct vision window located in the left side forward window will give a little more airflow to cater for those hot Australian summer days.
After climbing aboard into the right seat of the Seminole and adjusting my seat, we were ready to get going. As it was quite a cold windy day at Moorabbin on our test, we decided to close and lock the cabin door instead of leaving slightly ajar while taxiing.
The door is secured by the traditional Piper method of rotating the latches at the top and front edge of the door. Should the door not be locked completely and come open in flight, there is a checklist action that requires the pilot to slow the aircraft to reduce the air loads before attempting to re-close and lock the door.
The preflight checklist includes a multitude of items for this type of aircraft, but at least it would get students to appreciate the types of procedures they would use in their careers later as commercial or airline pilots. There’s no ‘kick the tyres, master switch ON, light the fires and we’re off’ in the Seminole.
Starting the twin Lycomings was fairly straight forward and with the Avionics Master ON, the Avidyne EFIS began its boot-up process and after the appropriate engine temperatures were warmed up into the green, we taxied for the run-up bay.
Taxiing the Seminole is fairly standard for a Piper aircraft. The nosewheel is directly linked to the rudder pedals and steering forces are quite light to taxy around bends on the taxiway or to keep the aircraft straight in the moderate crosswind that was blowing.
On long straight runs especially when the wind was behind us, I needed to give quite an application of brake to drastically slow the aircraft and then let it accelerate away again to avoid riding the brakes to control the taxy speed.
Lining up on runway 35L at Moorabbin, and with a smooth application of full power, the Seminole accelerated quite rapidly. Easing back on the control column initially didn’t generate the rate of rotation at liftoff that I was expecting and I had to use quite a bit more pressure.
The elevator pitch trim had been correctly set and confirmed during the pre-takeoff checklist; it just needed a good pull back to go flying.
Once away from the ground, all the dodgy stories that had been related to me by colleagues seemed erroneous as the Seminole climbed away at a good rate of climb at 88 KIAS; more than enough to have to adequately anticipate any low level altitude restraint in leveling off.
Care needs to be exercised in controlling the acceleration prior to gear retraction as the retraction speed of 109 KIAS could easily be exceeded.
Heading out to the area to the south of Moorabbin at 2500 feet, the Seminole delivered 130 KIAS at 23 inches and 2300 rpm. The MFD engine display showed a fuel consumption of 11 US GPH per side.
My initial impression of the handling was again like an old friend revisited. Although faster than the PA-28s that I had flown many years ago, the handling characteristics were classic Piper. I found I needed minimal rudder input to balance turns.
Synchronising the engine RPM was a bit of a chore considering there was a little bit of a stagger in the pitch levers evident. Again this is an aircraft that has actually been flying since 2008 so it’s understandable, plus it had recently had some engine work carried out.
Once the beating in our ears was solved, we continued our cruise out to the area and eventually up to 4-5000 feet where I wanted to have a look at the general handling qualities including stalling and asymmetrics.
For a T-tail aircraft the stalling characteristics were fairly straight forward. The first noticeable warning was with the closing of the throttles, you immediately get the ‘hey idiot you’ve left the wheels UP’ warning horn.
It was a bit annoying every time the throttle was closed, but I’d rather have that in a training twin than have the alternative consequences: a wheels-up landing. The horn can be canceled if necessary by pressing the mute switch above the standby ASI. On this occasion we elected to cancel the warning as we would soon be increasing the power setting.
In the clean configuration the stall warning horn began sounding at 67 KIAS with pre-stall buffet becoming more noticeable at 64 KIAS accompanied by a slight wing drop. In the approach configuration this speed reduced to close to 55 KIAS.
Flying out of whack
Next I explored the asymmetric handling by simulating an engine failure without actually shutting the engine down.
This was achieved by setting the propeller control to high RPM and then advancing the throttle to achieve an engine RPM to 2180 to simulate the drag condition of a feathered engine.
At 5000 feet and with the right engine set in this condition, we were able to achieve a rate of climb of 300 fpm at 88 KIAS whilst holding 5o of bank toward to the left. Rudder forces weren’t that heavy to maintain the skid ball centered.
After restoring symmetrical power, I checked the roll rate in some turn reversals from 45o to 45o with fairly normal rates of 3-4 seconds.
The descent back to Moorabbin was somewhat drawn out as we kept the power set at 18 inches and 2200 RPM to keep the landing gear warning horn from sounding. This resulted in a descent at 140 KIAS and 500 fpm.
Entering the circuit area, the first landing was demonstrated to me from a long straight-in approach.
After the touch-and-go, my attempt from the next circuit resulted in a go-round from the flare. After having approached at 80 KIAS and while approaching the flare, I began to reduce the power and raise the nose to reduce the rate of descent.
Like on take-off, I found the stick forces a little higher than I had expected and when the ground was still approaching at a high rate, I over-flared and decided that the better decision was to go around.
The engine response was immediate and we were quickly climbing away for another attempt. The full-stop landing was much better. On landing I found the braking to be very efficient with relatively light forces; this made it easy to make the desired exit taxiway.
In all I found the Seminole to be a very capable twin trainer; it doesn’t have the world beating performance to leave your stomach back on the runway as you launch airborne or to exhibit single engine rates of climb to compete with a modern single engine aircraft; this is not its role.
The role of the twin trainer is to provide the student with a platform where the pilot can learn about how to handle problems associated with twin operations whilst flying the aircraft in the various phases of flight, and with really only one other competitor in the market place, the 30-year-old design competes well now it has modern avionics fitted.
The Seminole offers the reliability of all-metal construction that any LAME around the bush can fix as compared to composite structures, which–although becoming increasingly more prevalent–require a bit more specialised skills to repair. After 30 years of construction, there must be something right in the original design.
A similarly equipped 2012 Seminole with Garmin G500 will set you back between AUD$740-750,000 (incl. GST) based on current exchange rates. If you want to add some weight to the aircraft, even air-conditioning is available as an option. More information can be obtained by contacting Brian Jones at Piper Australia Aircraft Sales on
(03) 9587 2899.