Techlink :: Tech Practice :: Hard Materials

Drive 500m down the road from Hamilton International Airport and you will come to two large hangars which are the home of Pacific Aerospace Corporation. New Zealand's only aircraft manufacturer, Pacific Aerospace is well known, especially in military circles, as the manufacturer of the CT-4 airtrainer, a pretty little aeroplane with side-by-side seating for pilot and instructor, a bubble canopy and a 300 horsepower engine which is used to train pilots by the Royal New Zealand Airforce, The Royal Australian Airforce, The Royal Thai Airforce and a number of others besides. At time of writing it was in fact already on a shortlist for the Israeli Defence Force and, as one might imagine, the IDF is a pretty exacting customer. Pacific Aerospace is also the home of the "Fletcher" aerial top dressing plane (now supplanted by the Cresco) which can be seen wheeling and dumping fertilizer over the hills of New Zealand. In other words, with three successful aircraft in its history, Pacific Aerospace is no newcomer to light aircraft manufacture.

multi seat

The new multi seat 750XL aircraft

Maintenance being performed on one of PAC's 750 XL aircraft

PAC 750 XL First Flight

PAC 750 XL First Flight Over Hamilton, New Zealand, 9/5/01

But what Pacific Aerospace has never tried to do before is build an aircraft as large as the 750XL. Sitting in the hangar, engine cowling removed, and still clad in an ugly ochre primer, the 750XL prototype is easily three times the size of the CT-4 parked nearby Its wingspan is 12.8m, length 11.58m and its maximum loaded weight of 3.2 tonnes makes it twice as large as the two-seat Cresco the firm has been making since the 1970s. But this aeroplane is not the size it is by accident. It is the size it is because three American skydivers who have since set up Utility Aircraft Corporation in the United States to distribute the 750XL were looking for an aeroplane that did not exist.

COP Brief development

When they visited general manager Graeme Polleyand his design team in January 2000 they told the Kiwis what they wanted was an aeroplane that could carry 18 jumpers to 14,000 feet in 16 minutes, and preferably for less than US$1 million. (Conceptual statement)

What they liked about New Zealand was that here was a country of people with a can-do attitude and an appetite for thrill-seeking sports and pasttimes which litigation-whipped US manufacturers ran a mile from. After a few mumbled feasibility conversations in the corridor the Hamilton manufacturer accepted the challenge.

PAC 750 XL

PAC 750 XL First Flight Over Hamilton, New Zealand, 9/5/01

Comparitive size of interior

COP Outcome development and evaluation

Mr Polley says one of the first things the design team did was start working on a physical mock-up made of wood. "You can do as many drawings as you like but there are some practical issues that you can only understand by physically climbing in and out of a mock-up to get an idea of what those numbers actually mean", he says. The mock-ups also became the focus for the manufacturing team to become involved in the design process. "It's easy to get a situation where the manufacturing guys criticise the design guys ideas, so I threw it open to the manufacturing team to have some input into the design and we got some very good input from them." Mr Polley says.

Having wrestled with the physical dimensions of the aircraft the designers, a team of two engineers and highly experienced draughters, fired up their AutoCAD stations and tried to find components from the CRESCO that could be pressed into service on the 750XL. While 25 percent could be reapplied this was less than had originally been anticipated.

COP Planning for practice

Part of the reason for this is that the 750XL will be one of the first aircraft in the world to be built to the FAA's Amendment 53 rules. PAC obviously needs to build an aircraft it can export and to get an aircraft accepted into the American market it needs to meet the requirements of the United States Federal Aviation Administration. When they approached the FAA, PAC was told that if it built its aircraft to the latest amendment it would have no problem obtaining approval. The only snag was not all the component manufacturers are up to Amendment 53 standards and so long as they are manufacturing for earlier aircraft they don't need to be. This can create problems. For example the fuel valves in an aircraft only permit fuel to flow in one direction. The new rules say it must be impossible to mount the valve the wrong way around but the manufacturers are building to the old rules which allowed the same connectors at both ends. Result: PAC has to develop a mount which meets the requirements of the new rules while using components made for a mass-market of old-rule aircraft.

One component which very definitely is the same is the Pratt and Whitney PT-6 turbine which powers the aircraft. At NZ$600,000 each they are a large proportion of the final aircraft's cost but the engine has proven itself in the Cresco as extremely reliable and able to cope with the heavy demands of repeated take-off and landings that aerial top-dressing requires with ease.

PAC operates all of its own fabrication facilities on site, with CNC milling machines, a large laser cutting machine and a staff of highly experienced aluminum components craftsmen. Mr Polley says keeping staff, particularly if the dairy industry is busy, is one of his more difficult challenges. He says while the company has tried outsourcing work it has often had difficulty with subcontractors' inconsistency of standards which has tended to make the company more self-reliant.

One of the biggest potential problems facing the 750XL is it could easily be too successful. The Hamilton plant can at best only make one a month. If the aircraft is a hit that capacity will not be enough. And there is good reason to think the plane will be a hit.

For a start it has been built to climb. This will please the skydivers who want to get people into the air as quickly as they can and in the US alone there are an estimated 800 aircraft needed for this market. The tandem diving craze, in particular, has seen a huge increase in the number of people involved in, skydiving, as otherwise staid office workers spice up their tourism experience with something more exciting.

The 750XL has also been designed to land on floats. With many of the old World War Two-vintage Beaver aircraft in the Canadian north facing retirement Mr Polley believes there will be demand for a reliable floatplane which can carry a reasonable load into remote locations.

The military too are another potential market. Cheaper than a helicopter and able to land and take off again on very short strips Mr Polley says the 750XL would be ideal for quietly inserting troops on patrol in East Timor without the racket of an Iroquois. He also sees the the 750XL being useful to forces in any mountainous country from Papua New Guinea to Vietnam.

But what of the competition? Well, at the moment there isn't much. The 750XL is designed to be a fairly rugged aeroplane in a very specific market segment. While the Russians certainly make aircraft of this kind Mr Polley says they are very definitely Russian which often means they are hard to fly and use techniques and controls that are not familiar to American-oriented pilots and service mechanics. Mr Polley says PAC designs like an American company, right the way down to using Imperial measurements because that is the way the market works.

COP Outcome development and evaluation

But this is all a little premature. After all the aircraft hasn't even flown yet. As this article goes to print PAC will begin working through a three-inch thick stack of flight tests overseen by the New Zealand Civil Aviation Authority. In a novel arrangement brokered by PAC the CAA will be administering tests not only for itself but also for the FAA. This means that the 750XL is being tested for certification in both the United States and New Zealand simultaneously. When the flight test programme is complete the aircraft will be certifiable in just about every market that matters and while the flight tests are expected to result in some modifications Mr Polley is confident that there will be no serious surprises.

The PAC 750XL is ready to take off but where it will take PAC nobody can be sure.