Airtest – Swearingen Merlin 1118

Whether this nation likes it or not, it will of necessity have to follow the lead of neighbouring global regions who have already opted for turboprop transportation, both within and outside their country, as a cost-effective means of commercial viability.

Many leading corporate houses in Australia still follow the pessimistic contention that key executives and board members should not travel in the same corporate aircraft – and to this end, cut off their noses to spite their faces by not investing in an airborne company workhorse for getting manpower and freight to other national centres or hubs of industry.

They would, according to all reports, rather queue up at airline departure counters or sit in airport lounges after their support staff have indulged in a telephonic exercise which often results in antics guaranteed to give any time and motion expert the horrors.

Their philosophy is knocked for six even before it starts – there is no God-given guarantee that the aircraft in which they eventually sit will not crash or otherwise malfunction, resulting in either a late arrival or even a non-arrival.

This backward-looking attitude in Australian corporate business is, thank goodness, being reversed as international business liaison brings to light the fact that a significant proportion of overseas men of commerce are already hooked on the corporate machine concept.

It’s not just an ego trip, tax holiday excuse or an expensive reason to slide into the red at high speed. It is sheer economic commonsense.

A glance at our Pacific neighbours shows the trend. In the US turboprop sales recently recorded a 27 per cent leap upwards, topping figures for an already record corresponding period the previous year.

In fact, turboprops, with their fuel-conscious operation and fast, smooth operation in all weathers, have notched a bigger percentage gain in the US than any other class of aircraft, as American corporate concerns and charter operators realise that this is the only sure way to combat future droughts of conventional avgas.

One of the front-runners in today’s world turboprop market is the Swearingen Aviation Corporation, headquartered at San Antonio, Texas, now a subsidiary of Fairchild Industries.

Marketing one of the most professional aircraft in the GA field, the husky-looking Merlin IIIB which had a quiet Press in this country on arrival, Swearingen is pinning a lot of justifiable hope on getting a lucrative corner of Australia’s corporate-buyer sector – which has really been. hardly tapped thus far.

The fact that Australia’s market share of GA aircraft is tiny when compared with other nations is not relevant – the objective in any campaign is to literally leave no stone unturned.

AADR evaluated the Merlin IIIB during a recent visit to Sydney by a Stilwell Aviation team. The Merlin was being used basically as a back-up aircraft for the Lear maritime reconnaisance demonstrator.

We came away convinced that there is an aircraft for Australian conditions, capable of operating fast, reliable and undeniably fuel-efficient corporate services within Australia and also to neighbouring nations when needed, and capable of mounting a galaxy of different roles.

The Merlin IIIB by Swearingen is a distinctive aircraft, both on the ground and in full flight. It stands tall on a short-coupled undercarriage, a no-nonsense machine giving the impression of being capable of earning every cent of its capital cost and DOCs.

The man who was undoubtedly the guiding light and midwife to this new generation machine, Ed Swearingen, really began its evolution as far back as the early 60s.

Although much conjecture has been aired with great knowledge about the Merlin’s upbringing, it’s certain it first became more than an idea when Swearingen began converting Twin Bonanzas with new motors and airstair doors.

He was also retrofitting bigger engines on Queen Airs.

When the Merlin line was born with the Merlin I, Ed Swearingen wedded a Swearingen fuselage to a modified Queen Air or Twin Bonanza wings and landing gear. The idea was to produce the I as a normally aspirated pressurised aircraft, the II is a turboprop.

The Merlin I never entered production. The biggest nail in its coffin was lack of suitable engines.

The II entered production with Pratt & Whitney PT6s, and eventually became the IIB when the P&W turboprops were replaced with Garretts – specifically, the Garrett AiResearch TPE 331 boasting 665shp (shaft horsepower).

With the design of a new wing came the Merlin III and IV. The Ill was destined to retain the ll’s basic fuselage and be aimed at the small/mid-corporate market, the IV being stretched and offered to the larger corporate sector, having the same body as Swearingen’s Metro commuter aircraft.

More about this Merlin III; it was developed around the same time that the first corporate jets filtered into the world market. The Merlin Ill couldn’t match the pure jets in speed, so Swearingen concentrated on range as the selling draw. With III fitted with a brace of 840shp Garretts, range was stretched at economy cruise to a mammoth 2350nm.

And during the in-fighting between turbo and pure jet corporate machines, it was found that on stage lengths under 250nm, block times were literally within minutes of each other.

Came the IIIB; shaft horsepower has been increased over Ill, by fitting a pair of Garrett AiResearch TPE 331-10U- 501C turbos. With the Dash 10s driving four-bladed props, and fitting an extra gear in the reduction system, the IIIB has slower-turning props which in turn lead to a quieter aircraft.

Acutely conscious that turboprops like the Merlin aren’t bound by America’s FAA Part 25 (airline) requirements, and this would inevitably lead to the collection of concentrated flak from the pure jet opposition, Swearingen did the obvious thing:

A savagely-efficient static fatigue structure was set up at Fairchild’s Farmingdale, Long Island, facility, and a Metro strapped into the torture rack.

Fuselage, wings, tail section, engine nacelles and other points got the full works in stresses, while the pressure vessel got similar treatment at an average rate of 12 load cycles each 60 seconds.

At last report, the ill-treated Metro had successfully withstood 70,000 simulated flight hours of testing in the rack, in all regimes, and is looking round for more. . . .

The final target figure is at least 105,000 simulated flight hours.

Meanwhile, Swearingen is offering the Merlin family (including our test IIIB) as the biggest, most fuel efficient and superior quality turboprops available today.

We had already seen the Merlin IIIB ’79 version at Schofields in the static park, and gone through perfunctory motions with Stilwell’s chief demonstration pilot Neil Morris. He brought VH-TCE to Sydney airport for this evaluation.

A second look at this Merlin brought to light a number of new points; maximum landing weight has gone up 1000Ib to 12,500Ib, and an update in performance data following extensive flight testing which has stretched the IIIB’s max range to 2838 statute miles.

Improved take-off and landing performance has also been achieved. Take-off distance has been chopped to 2965ft. Despite a 1000lb landing weight increase, landing run has been increased by only 39ft.

According to Neil, Swearingen’s VP Marketing Richard Robinson has gone on public record as confirming the Merlin IIIB’s world class distance record achieved on a delivery flight from New York to Cologne, West Germany – 3792 miles nonstop.

Robinson has also admitted that demand is outstripping supply; a substantial backlog of orders now exists, and Swearingen has already upped production rates without sacrificing quality of product.

Walking round the IIIB failed to convince us that this husky 16. 82ft tall machine is still a GA aircraft. The entire set of the Merlin ThreeBee reeks of power, sleekness and an urgent desire to get off the ground and fly.

Preflighting externally is split into five separate sections – cockpit (eight checks), tail section (eight), right-wing (21), nose (seven), left-wing (23).

Before installing ourselves in the cockpit, the AADR team checked the interior – which is where the corporate action usually is.

The evaluation aircraft was fitted out in one of the several optional corporate configurations – a 10-place setting (including the two bodies up front). Four passengers can be accommodated on a long divan running down the port side, with separate club seats for the others. Le biff (the loo) is certified as a seat when not in use for other purposes.

The Merlin’s cabin is fully 57in high, roomy, and appointed to give maximum spaciousness and offsets to the maximum the fact that headroom diminishes towards the outboard sides. Total cabin length is fully 209in, with an additional 82in in the rear baggage compartment which itself is backed by a mirror to enhance the optical concept of added space.

With an overall 62 in cabin width to play with, Swearingen’s designers have made optimum use of an uncompromising pressure vessel. Options include rotatable executive chairs which also track fore and aft and recline; stowaway work tables; full-size completely equipped refreshment centre/galley; a big and completely private toilet with a vanity and loo; plus many other openings, shutting, stowing and folding items of corporate gear.

Continuous floor-mounted track permits QC modification of the interior.

Even brief study of the Merlin IIIB before entering the cockpit’ proves the aircraft could be accused of being overbuilt. There’s so much fail/sale integrity in the machine one could almost swear it was a much bigger RPT aeroplane rather than a 12,500Ib GA type.

Fuselage is all-metal semi-monocoque, built in three main sections – nose, cabin and tail, flush riveted and reinforced at windows, doors and joints. Wings are double-spar, with a five-degree dihedral and “wet” to take 648 galls/US fuel.

Some have called the Merlin IIIB a very electrical aeroplane. It’s true – there are DC and AC power systems, massive over-voltage protection, multi-bus systems, a mass of redundant circuitry to ensure emergency backups, plus the usual electrically-inspired items one expects in something the size of an RPT pure jet – or at least an F27.

This electrical accentuation is reflected in the cockpit (one could without telling an even small white lie refer to it as· a flight deck, such is the proliferation of professional gear).

Two side consoles are replete with circuit breakers, bus circuit diagrams and other electrical gear controls. The main panel would take a supplement to this edition to detail, but basically the panel (I to r) houses flight and avionics instruments; a line of rocker switches below the instruments; engine and fuel flow, temperature and percentage gauges; a mass of digital nav/com and assorted long-range avionics; an all-singing all-dancing annunciator panel covering every malfunction from wing overheating to anti-skids or Beta fallout; and angle of attack indicator; Bendix colour radar; and more fight and nav instrumentation.

The central power pedestal also sprouts controlling gear, switches and equipment.

Suffice it to say that pilots flying the Merlin IIIB are usually sent to a simulator for at least two days before trying the real thing.

Pre-start includes checking door integrity, cargo and baggage, and “No Smoking” and “Fasten Seat Belts” signs before turning attention to the console, where a lengthy check awaits.

Essential bus tie switch, ignition mode switch, unfeather/negative torque sensor switch (this NTS system automatically reduces drag against a dead engine by moving the prop blades towards Feather), and the Merlin’s SRL switch (Single Red Line actually computes a single maximum engine temperature value for all flight and engine conditions above 80 per cent rpm); in all, there are 13 console checks before turning to the instrument panel where a dozen more items await checking. Co-pilot’s console checks include four more items, with the pedestal listing 17 more.

Starting is relatively quick; 20 specific actions follow battery switches ON – one holds in the START button until revs reach 10-12 per cent, and watches the ignition indicating by rising temperature and illumination of the ignition light. Temperature is monitored with a 770C maximum, rpm stabilised at 69 per cent plus or minus one per cent, fuel and oil temperatures in yellow or green arcs, generator reset/on, and SRL fail light checked off above 80 per cent.

First start is usually on the right engine, with the same basic procedure for the left motor.

Pre-taxi includes checking the SAS2 (stability augmentation and stall avoidance system), and 14 other components; taxiing includes arming the nosewheel steering switch, testing yaw damper and anti-skids.

A stick-pusher check proved interesting en route to the holding point. The Merlin’s stick-pusher operates below 1. 75Vs (stall speed) and increases until at 1. 35Vs a forward shove of about 20Ib is battling your backward heave.

At 1. 02Vs the force of the pusher builds up to a constant 65lb.

We were at a computed 10750lb for this take-off, with Vr at 105kts indicated, lift-off at 110, best single-engine rate of climb at 129kts and best twin-engine roe at 142.

Take-off was exhilarating – a steady buildup rather than a boost in the derriere. With nine degrees of Fowler flap down, we tracked truly – for the purist, the Merlin has three types of ground steering; super-sensitive for pre-take-off manoeuvring, power steering for speeds up to 60kts, and rudder steering for the rest.

Vr came on cue, with wheels off a fraction later; we made it in far less than the carded gross run of 2965ft – about 1000ft less, but then we were about 2000Ib below max all-up and the wind was kind.

Stick force to unstick the Merlin was light enough. Wheels up and cycling lights on, flaps came up in what seemed to be an instant later with minimal pitch changes. Initial rate of climb went whanging past 2100fpm, with 150kts showing, 80 per cent torque and 100 per cent rpm.

On the way up, we had time to check the fuel bypass light – the light comes on if ET (engine temperature) tops a specified reading, bypassing fuel and thus limiting power and temperature. Pilot action is to retard the power levers and monitor the torque meter.

At 4000ft the Merlin under evaluation was boring upwards at 3200fpm, still on 100 per cent rpm and indicating 138kts.

Little wonder that the Merlin’s capabilities include a higher power/weight ratio than a combat-ready Mustang. . . .

Our destination was Canberra as the turning point, then back to Sydney via beacons. All the relevant data had been punched into the multi-way point long-range avionics slaved to the do-everything-but-make-the-tea autopilot by Bendix.

Climb to operating height was a series of readings, and further study of what makes this Three B such a wonder machine.

Apart from the multi-mode avionics and nav/coms which enable the Merlin IIIB to go anywhere and do almost anything at any time, it’s cleared for single pilot operation by DoT.

Although the asking price for this test copy was about $A1. 4 million, the outlay includes pilot training and a complete backup service.

(Through the transition layer, reset altimeters, monitor cabin pressurisation feeding in gently to its routine 7psi differential – giving sea level conditions inside the cabin at nearly 17,000ft, and 7300ft interior height at the aircraft’s certified ceiling of 31,000ft . . . FL (flight level) 120, OAT +15, climbing at 1700fpm and indicating 180kts – that’s 226kts true. . . . )

Why did Garrett go for a SLR (Single Red Line) computer? It was a matter of economics – with TIT (turbine inlet temperature) usually nudging 1000C, sensors would need replacement with monotonous regularity.

So Garrett came up with the SLR – the measurement of several variables including EGT, OAT (outside air temperature), total head temp at engine inlet (TT2), pressure ratio across the engine, and engine rpm.

All this info is fed into a microprocessor and what comes out is basically a single do-not-exceed value of EGT. To ensure no overheat in the system, the fuel bypass with its blue lights is a fail/safe backup warning system.

(Flight Level 150 . . . OAT +10, 98 per cent rpm, 60 per cent torque, trueing out at 287 knots . . . that’s 330 miles per hour in temporary cruise at this height . . . Manual graphs show this to be near the max cruise numbers. . . . )

We got to Flight Level 250 about five minutes before altering heading over Lake George, for Yass, and watched with something not far removed from incredulity as the fuel flow figures for each hummin’ Garrett came tumbling down below the 230I6/engine mark, torque percentage dropping to 50 per cent meanwhile.

Other AADR checklist readings at this height included:

OAT -25, rpm still at 100 per cent, indicated airspeed 187kts, thus true airspeed came out of our Kane at 285kts (nearly 330mph).

Boring on up to an operating height of FL300, Neil passed on the information that Merlin DOCs hovered between an incredible $90 and $100/hr, working on 800 hours annually.

One could work on an average fuel consumption in flight of about 500I6/hr, he added. At FL300 we were burning far less than 200I6/engine, so the Merlin must be a thirsty beast at lower levels. . . .

At this height the announcement was made to our three bodies in the main cabin, lolling in luxury and in one case taking decibel readings with enthusiasm from a portable meter (and hardly getting a worthwhile reading – decibel readings in the Merlin cabin have been recorded as low as 80dB), that we were in an atmosphere of 7500ft.

More readings at this Flight Level; 100 per cent rpm, 40 per cent torque, fuel flow still a laugh, speed creeping up from 145 indicated to 158kts. Outside air -35C, which gave us a TAS of 262 according to our confuser – more than half a mile for a pound of jet fuel, said the Merlin Manual.

Ground speed, taking the wind of 260/85 into account, gave us a mark over the ground of 360kts; believe it or not, that’s about 415mph – and in a GA twin, to boot.

Came the time for letdown, reluctantly but inexorably. With a descent rate of 2000-2100fpm we neared redline speed but held it so that by FL130 (OAT OC) we were indicating 238kts – 297kts TAS. Torque had dropped out of sight at 5 per cent.

Mild handling en route to Sydney disclosed that the Merlin has comfortably light pitch and rudder forces for manoeuvring, but moderately heavy ailerons – typical of this Big Bird class.

Single-engine flying we didn’t do on this sortie; but the IIIB is fitted with a rudder bias system which shoves in a 4016 force to compensate for dead engine yaw. This, coupled with the negative torque sensing (NTS) system, does a lot to alleviate an awkward situation.

The IIIB’s single-engine climb performance is booked at 723fpm.

In the Sydney airport circuit, the Merlin IIIB handled in docile enough fashion, but needed a firm hand to let it know who was flying this thing.

Wheels came down at 1500ft, with the aircraft indicating 158kts (Vlo is 173kts) and giving a strong pitch. With 120kts glued to the ASI, half flap was lowered at 900ft, with full Fowlers coming down on short finals.

The port wing showed a sudden tendency to drop out of the sky as we initiated short finals, but quick wheel counteracted the freak shear plus a whiff of horsepower.

Speed eroded quickly over the fence to nudge the book’s stall speed of 89 indicated. Power levers came right through into Beta for reverse thrust and, despite the prewarning that it was going to be a short-field, our cabin crew showed a strong tendency to bust their straps and-joins us up front.

With braking we were able to make the first turnoff on Runway 16, leaving the rest of the 3962m runway to the seagulls and fresh air.

AADR wishes the Merlin IIIB well in its entry to the Australian market; the competition is keen and fierce, but Stilwell’s merry men aren’t exactly green when it comes to gutsy marketing. We can only repeat our comments made at the beginning of this report – and hope that as many corporate men as possible read them, abandon their almost Victorian dogmatic attitudes to putting their corporate eggs into one airborne basket, and get with the 20th century – in a Merlin IIIB.