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FEATURED AIRCRAFT
Flying GippsAero’s Airvan

Gippsland Aeronautics (now GippsAero) co-founder George Morgan remarked ten years ago: “We’re a research and development company and we don’t see ourselves as a major manufacturer. We can supply a small market- but not a mass market- and the product’s too good to miss out on a substantial global opportunity.”

George certainly turned out to be right about the product- and the majority ownership deal with India-based global manufacturing giant Mahindra has greatly benefited the company’s mass-market reach. With over 150 Airvans in service around the world- GippsAero is now almost daily expanding its capacity- planning new extensions to its manufacturing facility and adding staff to address the global market. Having also acquired the type certificate for the GAF Nomad- Gippsaero will soon have a four-aeroplane product range of utility singles and twins that will bring notable new products to an innovation-starved market.

My first glimpse of the Airvan series had been a test and demo flight in GippsAero’s second GA8 pre-production prototype at Latrobe Valley about ten tears ago. Since then GippsAero had developed the turbocharged Airvan GA8TC-320- targeting a well-identified market for hot and high capability in locations like Papua New Guinea- Africa and other parts of the world where Airvans are already popular. This new development also opens opportunities for high-altitude sport parachuting and aerial surveillance- and anything else that needs that extra power and performance at any altitude. Also there’s a strong interest in floatplane applications- especially in Canada but also in other tourism and island regions- and GippsAero is negotiating with Minneapolis manufacturer Wipline to produce suitable floats for a demonstrator GA8. An Airvan has already been dispatched to California by sea to be the US demo aircraft and floatplane trials horse.

The Airvan already has very convincing credentials. Having developed and successfully marketed its own agricultural aircraft- the GA-200- the company had also identified a notable niche for an eight seat utility. They’d already got the wing right- proving its lifting capabilities and aileron performance on their G200 agricultural aircraft in that unforgiving environment- so they knew it had ample lift capability for an eight-seat aeroplane. Cessna helped the decision along when it re-launched its six-seat C206 while ditching the notoriously underpowered eight-seat C207- and the partners turned their attention to optimising their new aircraft to meet both market demands and new- exacting modern certification standards.

Thus was the GA8 Airvan concept born. Over 150 are now flying in more than 34 countries around the world- and currently some 75% of new-delivery Airvans are the turbocharged version- confirming the company’s market assessments. Kununurra-based (Western Australia) scenic tour operator Alligator Airways has recently traded its normally aspirated Airvan fleet for five of the new turbocharged variant- and factory-refurbished Airvan bargains are for the moment slightly depressing the market for conventional units.

The aircraft that GippsAero provided for our update was well run-in to say the least- having recently circumnavigated the globe- with Bendigo pilots Ken Evers and Tim Pryse flying 234 hours and 52-000 km in 55 days supporting a fund-raiser for the global battle against malaria. It also became something of a battle against tropical weather- but they returned with not a mark on the aeroplane- except for some prominent promotional signwriting. Veteran GippsAero test pilot David Wheatland- with whom I had flown the prototype- was also flying with me on the demo and knows every rivet in the Airvan: “I just love them-” he says.

It’s a tribute to the original design that nothing structural has been changed since that first acquaintance. The most visible features are the wide sliding cargo door towards the aircraft’s rear- and the all-flat floor. The door itself measures 1054mm2 with a sill height that matches a standard pickup truck- and can be opened in flight in all flap configurations. The super-strong cargo floor has ample fixtures for seat or cargo ring attachment. The strongest section of the floor area- boosted by the structure that links undercarriage and wing strut attachment points- is in the area nearest the door- which provides the highest allowable floor load intensity. It is also the best position for centre of gravity management. A fold-up step is provided for passenger boarding- and when in place becomes an armrest for the left rear seat passenger. The advantages of the fully-flat floor- both for cargo and sport parachuting roles- can’t be over-emphasised.

In passenger configuration there’s a small baggage shelf behind the rear seats- with an after luggage bin behind it. The optional composite cargo pod is a response to wide customer demand- especially in Africa where the Airvan is widely used for big game safaris. Except for the fairings at either end the pods are deliberately designed with a completely flat constant-section floor and one of the side doors bigger than the other at .66m to provide for extra-large baggage items. (Its developers actually bought the biggest Samsonite they could find as a basis for the design.) There’s a third door at the rear underside of the pod- to maximise the length capacity- and a length of pipe 2.43 m long and 10 cm cross-section can actually be loaded in the pod.

The Airvan has always been a comfortably stable and flyable aeroplane- thanks to rudder- ailerons and elevators that were designed to dodge gumtrees in the aerial fertiliser role- and a variable incidence horizontal stabiliser that provides a wide trim range without limiting aerodynamic efficiency. The half span rudder is on the lower part of the fin where it’s in the propeller airflow- and has excellent authority even on takeoff. The airframe is totally corrosion proofed to the same standard as the airlines- with no metal to metal contact- and for beach or float operations additional internal corrosion proofing is offered.

The aircraft is certified to the latest FAA requirement- Federal Aviation Regulations (FAR) Part 23 at Amendment 54. This means there are significant but mostly invisible built-in safety advantages- not the least being that the fuel tanks are a specified distance – about 0.6m – from the nearest passenger while still remaining inboard of the strut attachments.

The GA8 Airvan is rugged- gutsy- economical and versatile – a utility aircraft with honest and impressive performance- a number of attractive features lacking in competing types- superior and uncomplicated handling- and a price tag which will guarantee it continuing popularity wherever there’s a home for a truly versatile utility aircraft. We’d forecast it will retain its status as a tough competitor in the market shared with Cessna’s Caravan and C206- and as an alternative to Pilatus Britten-Norman’s Islander for many tasks.
The Airvan has clearly passed the critical point in its development- and we’ll be seeing plenty more of these significant aeroplanes in the future.

Other examples of advanced airworthiness requirements are the crew and passenger seating- which are tested to decelerations far exceeding the crashworthiness certification bases of many American aircraft still available as new aeroplanes- electrical systems redundancies- critical items- fuel systems delivery capacity- component lives- fuel systems and flammability- explains David Wheatland:

“We’re ‘flutter cleared’ in accordance with Amendment 54 which means a ground vibration test- an in-flight flight test at the critical configuration with vibration generated in the aircraft at 110% of Vne - something not required of previous-generation aircraft. Another example is that you’re no longer allowed to have to have a fuel flow indicator that measures pressure off the flow divider spider; you need a separate meter that actually measures flow in lb/hr- and most systems aren’t measuring that at all- they’re just interpreting fuel pressure. You’re not allowed to calibrate a gauge in fuel flow if it’s not measuring fuel flow. If you’re measuring fuel pressure and you get a blocked injector- the pressure goes up so the fuel flow goes up and in fact the fuel flow’s gone down- so we have a requirement saying you’re not allowed to label things incorrectly- and when they show something it’s got to be actually what’s happening.

“Modern certification requirements couldn’t possibly be met by a lot of new aircraft that are still on the market- but we’ve certified the Airvan to the current standard: No equivalents. No exceptions. No exemptions. We fully comply.”
Another product of modern certification standards- the Aircraft Flight Manual is a highly professional production which offers all critical data in both imperial and metric format- incorporates a pilot operating handbook (POH) and has been has been prepared to comply with the General Aviation Manufacturers Association (GAMA) Handbook Specification Number 1.

The whole design has low maintenance as a high priority. Elevators- rudder and aileron controls are cable-controlled- and the three-position single slotted flaps are mechanically operated with two extended settings- at 14° (normal for takeoff) and full flap at 38°. Nosewheel steering is by direct pedal pressure- with differential braking also standard- and minimum turn radius is about half a wingspan. Nosewheel suspension is through an oil-damped coil spring which- unlike conventional oleo nose gear- keeps the deck angle level during loading- regardless of load distribution because the spring is almost fully extended at rest and is only damped on the return stroke. The main gear comprises two separate tapered and faired 5160 chrome steel spring steel tubes. Cleveland wheel and brake assemblies are fitted and main tyres are 6 ply rating 8-50 x 6.

The wingtips are removable both for ease of replacement and for access to the internal wing structure- and numerous inspection panels are provided both internally and externally. The elevator trim system consists of a cable operated trim drum to adjust the horizontal stabiliser’s angle of incidence- using a large trim wheel on the side of the centre console.
The early prototype had been powered by a Lycoming IO-540 driving a three-bladed McCauley prop and providing about 280 horsepower- and even that temporary arrangement had produced impressive performance. But today’s demo aircraft was fitted with the original-design turbocharged fuel injected Lycoming TIO-540-AH1A- with a maximum continuous power rating of 300 BHP at 38” manifold pressure and 2500 RPM. The engine also has an alternate takeoff power rating (ATOP) of 40” MP at 2500 RPM which delivers 320 bhp but is limited to a maximum of 5000’ pressure altitude. Above this altitude take-off power is limited to 38’.

The initial design goal of an eight feet by four feet (2.4 x 1.2 m) flat floor in a constant-section cabin- has been only slightly varied by small 45° floor-to-sidewall insets to provide corner bracing- but still leaving about five square metres of flat floor area.

The 1270 mm interior- wide enough to accommodate a fairly generous aisle- is relatively spacious with cabin seats anchored to fixed floor points. A notable feature is the huge size of the cabin windows- which is one reason for the type’s popularity with scenic flight operators. The cockpit is the same width as the cabin- which allows plenty of space for the front seat occupants- as well as an ample instrument panel. Both front seats have four point restraint harness assemblies with an inertia reel fitted to the shoulder straps. Rear cabin seats have three point automotive style restraint harness assemblies with inertia reels fitted to the shoulder strap.
Crew entry is via forward-hinged doors on either side with small steps provided- and is easy because there are no obstructions. Panel layout is completely conventional- with flight instruments straight ahead of the pilot and nav instruments to their right. There’s also ample space for a dual right hand seat flight instrument panel. The small overhead panel is all electrics – circuit breakers- master switch and lighting controls – which aids in de-cluttering the main panel.
The fuel system is simple- with only ON and OFF positions. In the off position- the key cannot be reached to start the engine- and because it’s a firewall off cock- the engine will only run for a few seconds in the off position- all of which makes the system pretty well fail-safe. Maximum takeoff weight is 1815 kg (4-000 lb)- however an increased MTOW to 1905 kg (4200 lb) is currently going through engineering approval.

Conditions at Latrobe Valley for our test flight were close to ISA- with OAT at 14 degrees- and negligible wind. To evaluate performance against the charts we elected to use the alternate takeoff power rating (ATOP) of 40” MP at 2500 RPM- and to throttle back at 5000’ to 38’.

We’d loaded the aircraft to MTOW- and with flaps 14 takeoff distance graph prediction was 580 m- which (although I wasn’t counting the gable markers) seemed conservative as the aircraft flew off at a little over 60 KIAS- accelerating in a very positive climb to the recommended takeoff safety speed (TOSS) of 71 KIAS. With flaps up at 200’ we go to maximum continuous power of 30” MAP and 2500 RPM- climbing at 78 KIAS with the cowl flap open- and if my graph interpolation is right we’ll reach 10-000’ in 10.3 minutes. Comparable graph predictions for ISA + 15 (30°C) would be 10.8 minutes and at ISA + 30 (45°C) 11.2 minutes – very cheering numbers for a Papua New Guinea operator.

The addition of a cowl flap has provided improved CHT and oil temperature management that is needed for turbocharging- and mixture adjustments are necessary during climb to avoid rough running from excessively rich mixture; however mixture controls for economy are not recommended during climb.

For a relatively large single-engined piston-driven aeroplane the Airvan is so unusually easy to handle that as tourist operators confirm even extremely low-time pilots are comfortable with it- and quickly become fully confident. Because the pilot is well ahead of the leading edge- the wingtips are in the field of view and the view over the nose is ample. Upward visibility is about 45°- and turn visibility in flight is also good because the pilot’s eyeline is still well ahead of the leading edge- with overhead transparent panels providing improved visibility in steep turns – another PNG-friendly factor for turning in narrow valleys.

Elevator trim changes that come with varied power settings and speeds need considerable trim wheel movement- but once trim is set- in-flight movement is small- and any out-of trim condition can be corrected with only modest stick forces once the Airvan is trimmed for the weight position. Neither aileron nor rudder trim is provided- and neither was missed as control forces we so light.

Above the cloud layer in calm air- we checked stability in all axes. A large rudder-induced yaw at trim speed demonstrated the superior directional stability that’s designed into Airvan as provision for an autopilot- and Phugoid is well damped in all configurations. Typically in cruise- the amplitude is halved within three cycles and the flight controls are light and well-balanced. A full-deflection roll from 45 degrees left to 45 degrees right took about three seconds. Maximum power setting normally recommended for cruise is 75% of rated power- however power settings below this will result in increased range and endurance corresponding with the reduced fuel consumption- says the POH: “At a miserly power setting of 45% the GA8-TC-320 is capable of attaining an endurance of close to seven hours- using correct leaning procedures. The most appropriate power setting for altitude and other considerations may be derived from the tables [in the manual.]

In ISA conditions- 75% power at 10-000’ is obtained at 29” MAP/2400 RPM- burning 79 lit/hr (1.66 nm/lit in still air) for 131 KIAS. At 65% power in the same conditions you’ll lose only 10 KIAS and burn 67 lit/hr (1.83 nm/lit) for 121 KIAS. Typical surveillance loiter speeds of 90 KIAS extend endurance enormously- with 45% power using typical fuel burns less than 50 lit/hr.

Overall- the Airvan is comparable in all ways with most of the popular US light singles- and more docile than most at low speeds. In all configurations there’s ample elevator resistance and moderate aerodynamic warning of the onset of the stall- which is an extremely mild event with no tendency to drop a wing. In any attitude and in any CG condition the stall is preceded by a slight aerodynamic buffet- and an artificial stall warning horn activates 5 to 7 KIAS above the stall speed. All controls are effective up to and completely through the stall- there’s no noticeable tendency to enter a spin- and the aircraft remains controllable with both rudder and aileron well beyond the stall- which is easily and immediately arrested with power alone.

In a power-off clean stall with deceleration at one kt/sec- G-break occurred at 58 knots. With landing flap- we stalled at 55 knots and a height loss of about 80 feet. In a power-off glide in landing configuration- sink rate is around 1-000 fpm- and recovery from a gliding descent induces only about 20 feet of height loss. In a clean glide at 80 knots- rate of descent is under 800 fpm.

In the circuit- the Airvan feels completely comfortable through the range of speeds from 65 to 120 knots- again with modest and infrequent trim changes and easy handling right through the speed range. With the wing and tailplane almost in line- the down-flow off the wing with flap extended almost exactly counteracts the flap trim change.

It’s necessary to remind yourself that Airvan’s light controls and ease of handling can lead you to forget you’re flying a relatively large and heavy aircraft- and to underestimate the time needed to get yourself back to VFE of 100 knots. Controllability close to the ground is superior- and the aircraft is as easy to land gently as it is when light- even with a forward C of G. The wind had freshened a little since we took off and I found crosswind handling in a sideslip flare to be remarkably easy.

The GA8 Airvan is rugged- gutsy- economical and versatile – a utility aircraft with honest and impressive performance- a number of attractive features lacking in competing types- superior and uncomplicated handling- and a price tag which will guarantee it continuing popularity wherever there’s a home for a truly versatile utility aircraft. We’d forecast it will retain its status as a tough competitor in the market shared with Cessna’s Caravan and C206- and as an alternative to Pilatus Britten-Norman’s Islander for many tasks. The Airvan has clearly passed the critical point in its development- and we’ll be seeing plenty more of these significant aeroplanes in the future.

For the complete appraisal of the GippsAero Airvan visit -
www.avbuyer.com

More information visit –
www.gippsaero.com


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