History:

Over the years, in order to reduce the cost of operating an agricultural aircraft, operators have fitted a number of engines to the Fletcher FU-24 series and these have included converted motor vehicle and truck engines.

In 1995 Fieldair of Palmerston North fitted a 410 kw (550 hp) Chevrolet eight-cylinder VEE engine to ZK-EMO (c/n 266), stating it was more efficient, had a slower turning propeller than the Cresco, produced about 2,200 lb static thrust, had similar operational fuel consumption as the Lycoming IO-720, and had overhaul costs a third of the IO-720. This aircraft became known as the Fieldair Fletcher FU-24-550, and it was announced in 1994 the company’s fleet of 21 Fletchers would be converted to the new power-plant.

ZK-EGP (c/n 238), an FU-24-450, was temporarily registered ZK-USU and flown by Cliff Tait from Christchurch, NZ to Sydney, NSW in 14 hrs 35 mins on 9 September 1978 to commemorate Charles Kingsford Smith’s 14 hrs 25 mins crossing of the Tasman Sea on 10/11 September 1928 in the Fokker F.VII3/m Southern Cross. The aircraft refuelled and returned immediately, making the double crossing in a total of 27 hours. In March 1979 it became VH-MXD for a short period before returning to New Zealand to become ZK-EGP.

In the 1990s costs of engine overhauls for the Lycoming IO-720 engine, an eight-cylinder horizontally-opposed air-cooled unit, led operators to find an alternative and companies looked at converting large automotive derived units. In 1993 Super Air Ltd in New Zealand made application for the Civil Aviation Authority (CAA) to accept a 37 per cent increase in power for take-off with a five-minute limitation with no changes required to the aircraft envelope. A similar project was undertaken by Fieldair Ltd using another engine type but only the conversion of the Super Air aircraft took place and neither project proceeded to the certification phase.

ZK-BHG has had an interesting history. It was the ninth Fletcher FU-24 built and was one of 13 airframes imported to New Zealand by James Aviation Ltd of Hamilton. It was registered to Cable-Price Corporation Ltd on 24 March 1955 and fitted with a 168 kw (225 hp) Continental O-470E engine. It later went to Robertson Air Services Ltd of Hamilton but was retired for a period in May 1986. In September 1988 it went to Custom Blend Feeds and Fertilizers Ltd. In May 1997 it was obtained by Super Air Ltd and was fitted with a 10.5 litre Ford V-8 engine, receiving certification with this engine in January 2000, making its first flight with this engine on the 23 January.

The engine installation was designed so the engine power went through a chain drive and through a reduction gearbox but after further development this was changed to a geared drive. During its development it was initially fitted with electronic ignition but this was not a success and it was reverted to standard ignition. It was fitted with dual main wheels on the undercarriage but in due course these were reverted to single wheels. However, it seems this installation was not particularly successful and it, along with a number of other aircraft, was fitted with a Walter M601-D11NZ turbine. In this configuration it first flew on 28 November 2003. The aircraft was retired again in 2013 and the registration cancelled in July 2014.

Another aircraft in the series has been fitted with a V-8 diesel engine by Phoenix Aviation of Gore, NZ. William Patterson, a shareholder of Phoenix Aviation, obtained ZK-EUD (c/n 285) and installed a large German diesel engine on his farm at Waikaia, north of Gore. This engine produced about 224 kw (300 hp). The installation was carried out but seems not to have been successful as it is not believed to have flown. The aircraft was last noted stored at Gore.

In October / November 2018 Fletcher Fu-24-954 ZK-EUC (c/n 283) at Gore, was fitted with a German Raikhlin Engine Developments V-12 RED A03 turbocharged diesel engine providing 373 kw (500 hp). This engine has also been installed in Europe in the Yak 152 supplied to the Russian Air Force.

Further variants of the Fletcher FU-24 series have included the Fletcher FU-24 Tofura with a Pratt & Whitney PT6A-11AG engine of 410 kw (550 shp), the Fletcher Falcon with an LTP101-700A engine of 400 kw (537 shp) and the FU-24-550 with a converted Chevolet V-8 engine.