Airtest – Socata Trinidad

Steve Roughsedge, the Fixed Wing Sales Executive and Demonstration Pilot took me round the new facility before our flight and I must admit to being rather impressed.

Clearly Eurocopter International Pacific is solidly on the ground at Bankstown with a facility capable of supporting the fixed and rotary wing side of its activities in terms of spares and technical support, customisation, and general overhaul of airframes. For rotary wing aircraft, dynamic component overhaul as well as composite material blade repair has been established as an ongoing facility. There is also a direct full time computer link with Eurocopter factories to provide AOG support, which can also link in with the customer’s computer system.

The new facility originally came about as part of the bid by Aerospatiale to win the assault helicopter project (won in 1984 by Sikorsky with the Black Hawk), however, although unsuccessful, it has resulted in Eurocopter committing itself to a future in Australia which is certain to be of great long term benefit to our economy.

Returning to the Trinidad, Socata’s aim in designing the aircraft was to meet a perceived market requirement for a very stable IFR capable aircraft suitable for the businessman who wants to fly himself on business trips with reliability, and in comfort.

In order to meet the range and speed specification, the Trinidad required a high performance wing (with consequent higher loading than comparable aircraft of its class) this being compensated for by larger flaps to achieve an acceptable approach speed. An added advantage of configuring the aircraft with a high speed wing is that it is capable of handling turbulence with great aplomb.

The top end performance has certainly been met as indicated by the fact that at 65% power, at lower altitudes, it is capable of achieving a range in excess of 900nm, with reserves, trueing out at 155kts (287km/h) for a fuel burn of 53lts/hour. At the bottom end, the large flaps which are electrically operated through three positions, (up, takeoff and land), take up 65% of each wing and extend to 45 degrees. Interestingly, the flaps fitted to the slower fixed gear Tobago only extend to 35 degrees.

Because of the span of the flaps, only relatively small ailerons could be fitted, which are certainly heavier than comparable aircraft as I was to discover later. Lateral stability has been achieved by giving the wing a noticeable degree of dihedral. The normally aspirated version of the aircraft is powered by a Lycoming 10 540 C4D5D six cylinder, fuel injected engine, providing 250hp at 2575rpm and with a TBO of 2000-hrs. The Lycoming TIO 540 ABIAD engine for the turbocharged version, which is equipped with an automatically controlled charger, produces the same power, but maintains it up to 20,000ft under standard atmospheric conditions.

The publicity material for the aircraft states that the main spar (I have a morbid interest in main spars!) is milled from a solid block of aluminium alloy on the same machine used to produce Airbus components. In addition, all airframe components are submitted to a series of three anticorrosion (alodine, zinc chromate) treatments perfected for the French Navy Super Etendard fighter which is required to operate in a salt laden maritime environment.

A feature of the FAR 23 certification requirements is the placement of a life of an aircraft’s mainspar. The Trinidad’s is currently 10,000 hours but no aircraft is evidently near that figure yet. However, in accordance with standard practice, the wing life will be extended as it is proved in service.

One of the most distinctive features of the aircraft (and its less capable brothers/sisters) is the forward set fin and rudder. This no doubt eased problems with the design and installation of the all flying tailplane but it also contributes to the aircraft’s good 25kt cross wind capability by reducing weathercock effect. Small antispin strakes are also fitted fairly well forward on the under side of the fuselage in order to meet FAR 23 one turn, self recovery spin requirements.

The undercarriage has a relatively wide track and its trailing arm setup is capable of masking the rougher than usual arrivals. The gear is retracted and held up hydraulically, with emergency down selection achieved by dumping the pressure by pulling the emergency undercarriage lever.

The baggage compartment, which has a 65kg capacity, has a rather odd shaped door which is almost triangular in appearance. Whilst the door might look small, it will evidently take a standard suitcase. Access to the compartment from the rear seats can be achieved through zips on the Tourneau cover located above the load.

Entry to the cockpit is gained via two large curved gull wing doors on either side which are hinged at their upper surfaces, with the hinge line well inboard. One steps down into the cockpit rather than sliding sideways as with most light aircraft. A high level of comfort is provided by the deep soft seats which are best set in a slightly reclined position through the knob located on the inboard side of each seat. Seat adjustment is provided fore and aft but there is no adjustment for the rudder pedals. Easy access to the rear seats is obtained by lifting a lever on the outboard side of each front seat and tilting the whole seat forward in a similar fashion to coupe type cars.

Once settledin, it is immediately apparent that considerable design effort has gone into the panel and control layout to provide optimum ergonomic functioning for the pilot. Everything falls naturally to hand.

The flight instruments, lighting controls and warning lights are separately grouped to the left with the radios and other avionics in the centre, and lastly the engine instruments on the right. The latter are angled towards the left hand seat to overcome parallax error.

The warning lights are evenly divided into a left warning group and a right advisory group. The warning lights illuminate when items such as oil pressure, voltage, and vacuum drop VH-SDE below preset levels. The group also contains a warning light which indicates when the fuel is selected off, and when the park brake is engaged.

The advisory group contains four green lights which illumi- nate when the pitot heat, landing light, taxing light, or fuel pump are in operation. Two switches separate the two groups, one is a test switch which illuminates all lights, and the other is a day/night switch which changes the brightness of the accessory lights.

Oil pressure and temperature gauges are vertical strip reading instruments which are located together with the fuel gauges above the radios. Evidently the fuel gauges are now very accurate, a necessary improvement on earlier models.

The undercarriage selector and its associated warning lights are mounted below the instrument panel on the right, with the parking brake knob to the left. The latter is rotated to lock the brakes on rather than being pulled as with most aircraft, and is a far more comfortable control to operate as a result. Arow of electrical switches including the master switch and fuel booster pump is located ahead of the throttle, pitch and mixture control levers in the main console. Just ahead of the engine controls is the flap lever and its associated gauge. Immediately behind the engine controls are the elevator and rudder trim wheels with the fuel tank selector located at the rear of the console. The selector has now been modified from an earlier arrangement where the off position was located between the left and right tank selections, necessitating a momentary movement through off when making a tank change. The left and right tank positions are now selected by moving the selector either left or right, with the off position selected by depressing the selector and moving it fully to the left. It struck me that a pilot unfamiliar with a rudder trim might attempt to trim using the fuel selector; this would need to be highlighted during conversion to the aircraft.

Aileron throw is limited to a quarter turn either side of neutral which overcomes the usual knee problem for the right hand passenger. Electric elevator trim is provided on the left hand horn of the control column through the autopilot as would be expected.

As a nice touch, there is no need to slam the doors, levers mounted on each side of the cockpit are rotated, once the doors have been lowered, engaging the locks and completing the door closure. Since there is no aerodynamic lift on the doors, they may be left unlocked with the engine running to aid cooling of the cockpit.

Once I had settled in, and Steve had completed a run round of the cockpit, I started the engine following the usual procedures of priming etc and we were soon on our way. Visibility from the front seats is very good (as it is from the back as I was given to understand) and the aircraft’s attitude whilst taxying provides a good view ahead. Steering control through the rudder bar/nose wheel interlink was excellent. Control effort was light and the aircraft responded as expected.

Following engine run up at 2000rpm, and the usual exercising of the propeller control, cockpit checks were completed with Steve advising that the elevator trim setting needed to be one division back from that shown on the indicator for takeoff. Having been cleared for a rolling takeoff, full throttle produced a fairly rapid acceleration with the aircraft requiring very little rudder input due to the excellent rudder trim control. However, on both the first take-off, and a subsequent touch and go, I found that having raised the nose at the recommended speed of a little under 70kts, a fairly heavy pull was necessary to get the aircraft to unstick. Discussing this later with Steve, he mentioned that the aircraft appeared to unstick better with passengers in the back which would indicate a forward CofG in the two up situation. A little more rearward elevator trim would have helped. The maker’s claim that the aircraft is capable under standard conditions of carrying four passengers, their baggage to 65kgs, and full fuel would tend to support the CofG theory. (Not like a certain aircraft salesman’s claim that his company’s aircraft had an excellent range and payload, but not at the same time!!) Climbout was straight forward at 2500rpm and 25ins and 90kts (168km/h) during which we experienced a momentary bout of electronic tacho fluctuation. It was evidently a transient malfunction and didn’t manifest itself again during the remainder of our flight.

The most pleasing control aspect for me was the availability of the rudder trim to keep the aircraft in balance without the need for a speed sensitive foot. A lot of my youth was spent sitting behind a Rolls-Royce Griffon (18lbs of boost, 2750rpm and 2250hp at full chat) which soon taught you the value of a good rudder trim! The rate of climb matched the advertised figure of 1260ft/ min (384m/min) at sea level and we were soon at 3000ft (915m) at which point I tried a few turns, having first set the aircraft up at 23/23 as for cruise. As previously advised by Steve, the ailerons are by no means light, however having got the aircraft rolling the heaviness of the control was not a discomfort. By contrast elevator and rudder forces are comparatively light. Next it was into clean and dirty stalls where it was soon apparent that you would have to work hard to get yourself into trouble in this part of the flight envelope.

With the aircraft clean and at idle revs, I finally ended up with full back stick, with no sign of a wing drop and with no clear stall. The aircraft merely descended in a gentlemanly fashion straight ahead.

Similarly, with gear and flaps down and 15″, full back stick would not produce a stall but we were going down hill fairly fast. Recovery in both cases was immediate on lowering the nose and adding power.

I next tried a couple of leisurely wingovers where it was apparent that if done too exuberantly, speed build up could be a problem for the inexperienced.

Having completed our upper airwork, I engaged the autopilot for the return to Bankstown. Height and heading hold were good as was course capture. A useful facility is the attitude hold for climb and descent. This can be achieved by taking out the altitude hold channel and rotating the nose to the desired attitude having first adjusted power for climb or descent.

The autopilot will also capture and hold an ILS glide slope but we did not have the time to fly an approach to try it out.

Having returned to the circuit, the relatively high max speed for undercarriage and takeoff flap selection of 130kts was appreciated as it enabled the aircraft to be slowed down very easily. Full flap is limited to 100kts (185km/h).

The base leg was flown at 90kts (167km/h) reducing to 80 (148) on finals and 75 (139) over the fence. Attitude and trim changes were minimal on the approach which eased the work load and the arrival was well cushioned by the excellent undercarriage. The end of the runway remained visible during holdoff as it is not necessary to achieve a high nose up attitude. A touch and go was carried out followed by a full stop and it was with some reluctance that I taxied back to the Eurocopter facility.

Sunming up the aircraft, the dominant word to come to mind is smooth! It has the feel of a limousine about it and clearly that is its true role-taking people from A to B in quiet, dependable comfort.

I have a real problem now, and that is, when I win Lotto, is it to be the Bonanza or the Trinidad?