Transavia PL-12 Airtruk VH-TRJ (c/n 703) at Temora, NSW in November 2015 (David C Eyre)
Country of origin:
Single-seat agricultural aircraft
One 224 kw (300 hp) Lycoming IO-540-K1A5 six-cylinder horizontally-opposed air-cooled engine
- Wingspan: 11.98 m (39 ft 3½ in)
- Length: 6.35 m (20 ft 10 in)
- Height: 2.79 m (9 ft 2 in)
- Wing area: 24.53 m² (252.7 sq ft)
- Max speed at 915 m (3,000 ft): 196 km/h (122 mph)
- Max cruising speed at 75% power at sea level: 188 km/h (117 mph)
- Stalling speed flaps down: 73 km/h (45 mph)
- Max rate of climb: 156 m/min (514 ft/min)
- Service ceiling: 6,890 m (22,600 ft)
- Fuel capacity: 189 litres (41.5 imp gals)
- Range with max payload: 1,203 km (748 miles)
- Range with max fuel: 1,297 km (806 miles)
- Empty weight: 1,017 kg (2,242 lb)
- Max loaded weight [agric]: 1,925 kg (4,244 lb)
In the late 1950s Transfield Construction Pty Ltd was founded by two Italian immigrants to contract to do transmission line work in Australia. A subsidiary, Transavia Corporation Pty Ltd, was formed in 1964 to build aircraft. In about 1965 Luigi Pellarini designed the Bennett Aviation PL-11 Airtruck, in New Zealand, also known as the Waitomo Airtruck, using a complete Harvard cockpit with a sliding canopy and other parts from the Harvard but of similar configuration to the PL-12, being able to lift up to 1,361 kg (3,000 lb). It did not go into production mainly because of financial problems, but was developed by Pellarini to take a modern 224 kw (300 hp) Lycoming engine.
A prototype of the PL-12 was hand-made by employees of Transavia, the initial staff comprising six engineers and four apprentices under the workshop manager; and this was followed by a pilot production batch of three aircraft. Type Certification was received on 10 February 1966, and in November 1966 Transavia placed the Airtruk agricultural / utility aircraft into production. Subsequently the type proved quite successful in its intended role, although it has been out of production now for some years.
Built at the Company’s facility at Blacktown, NSW, the prototype VH-TRN (c/n 1) was assembled at Bankstown, NSW and flown for the first time on 15 April 1965 powered by a 213 kw (285 hp) Rolls Royce/Continental IO-520-A engine. The pilot was New Zealander Neil Johnston. This aircraft was later used as a demonstrator until retired and placed on display at the Power House Museum in Sydney, NSW.
First production aircraft was VH-TRD (c/n 601) delivered to Duttons Aerial Sowing of Glen Innes, NSW followed by VH-TRZ (c/n 602) which was shipped to New Zealand to J V M Kean Pty Ltd and became ZK-CTT with Barr Bros Ltd. It crashed at Matakana on 12 June 1967. The third aircraft was VH-TRJ (c/n 703) for Hazair Agricultural Services of Albury, NSW. It appears some 117 examples of the series were completed.
It was realised from the beginning that overseas markets had to be found as 90% of requirements for agricultural aircraft were for spraying, and it was mainly in Australia and New Zealand that the bulk of the agricultural flying involved spreading fertilisers, mainly super-phosphate. Early production aircraft went to New Zealand where the type built a reputation as a big-load lifter. In order to publicise the aircraft the Australian Department of Trade asked the Transavia Company to take an aircraft to annual agricultural shows in Nairobi and Capetown on the African continent, an aircraft VH-TRI (c/n 929) being fitted with a fibreglass fuel tank in the hopper to extend the range. It was flown by Mr R Williams, some demonstrations being given in Thailand and India on the way. Some 220 hours were flown and 28,967 km (18,000 miles) were covered. This aircraft later became ZS-WPO in South Africa.
The PL-12 Airtruk was a fully aerobatic machine with a limited load, and could be safely spun with a full load in the hopper. The twin-booms were interchangeable, as were the ailerons, flaps, shock absorbers and wheel assemblies, and tailplanes. The prototype was actually the second aircraft built, the first being built as a test airframe for destruction in static tests to determine the aircraft’s ultimate safety factors.
Deliveries of production aircraft began in December 1966 and a batch of ten was shipped to Flight Engineering Ltd in New Zealand for assembly. The separate tails allowed loading vehicles to approach between the booms for loading, there being 3.5 m (11 ft 6 in) between the tails, the twin tails staying clear of the spread of chemicals. Aircraft supplied to Thailand, which were spraying corrosive chemicals for treating oil palms, had stainless steel hoppers. For spraying the aircraft had an engine-driven constant-speed pump.
In December 1970 the prototype of a new model was flown, this being the PL-12U, which was designed as a multi-purpose cargo/passenger/ambulance/aerial survey variant, receiving certification in February 1971. Several examples of this version were supplied to Thailand where they were used in the counter-insurgency role, being fitted with standard weapon mounts that could take rocket launchers or machine-guns, or both. This version became known unofficially as the Bushranger. A further development mooted at one stage featured remotely controlled, rearward-facing, twin machine-guns to provide suppressive fire following a strike.
In 1988 at the Bicentennial Airshow at Richmond, NSW Transavia displayed a mock-up of a new variant known as the PL-12/N300 [also known as the PL-12 MIL] in medevac configuration, this model being aimed at Third World countries and offering STOL performance, good weight lifting capability, ten hours endurance and a large two-part door providing access for two stretchers and two attendants. It could also be used for aerial photography and para-dropping, or for carrying freight. In conjunction with AWA, the Australian electronics company, it also offered a surveillance variant with a VLF navigation system based on the Litton 3000 unit.
PL-12 Airtruks were sold in New Zealand, Malaysia, Singapore, Taiwan, East Africa, South Africa, Kenya, Thailand, Yugoslavia, Spain and North America. A number were supplied to China in 1986. In Thailand it was flown on rain-making experiments, and in Denmark it was used to spread detergent on oil slicks. In 1982 negotiations took place for a utility variant to be delivered to the Djajanti Group based in Djakarta, Indonesia, the aircraft to be based on Aru Island on the south coast of West Irian and to carry a pilot and four passengers or 590 kg (1,300 lb) of freight up to 644 km (400 miles). Some ten PL-12Us were built for utility work.
One (VH-EVY) was used in the film Mad Max 2 and was later retired to Airworld Museum at Wangaratta, VIC. It has more recently been sold and restored. Another ZK-DMZ (c/n G356) is on display at the Ashburton Aviation Museum in NZ; ZK-CJU (c/n 1239) is in storage at Ardmore; and ZK-CVB (c/n 706) painted as ZK-DMX is at the MOTAT Museum in Auckland.
Five Airtruks and seven Skyfarmers still appeared on the Australian Civil Aircraft Register in 2015 and three are still airworthy but are not used for agricultural work. The wrecks of a couple are under restoration for museums.