Pacific Aerospace Fletcher FU-24
Fletcher Aircraft FU-24
The Fletcher FU-24 was designed as a util-ity aircraft by John Thorp (as the Thorn T15) for the Fletcher Aircraft Corporation of El Monte, California, and N6505C (s/n 1) was built and first flown on 14 June 1954. As designed and produced by the Fletcher Aircraft Corporation, the first Fletcher FU-24 was of open cockpit design and access to the cargo section was achieved by lifting a large drop hatch on the right-hand side of the fuselage. Once the 30” x 45” hatch was opened, the cabin or cargo bay in this case, could hold a long item by sliding it into the rear fuselage or a half-tonne item placed and tied down directly behind the wing spar. The first FU24 aircraft had a 3500 lb maximum takeoff weight.
The air-craft was sent to New Zealand and made its first flight as ZK-BDS on 24 September 1954. Further testing was carried out before it was placed in use with Robertson Air Service Ltd of Hamilton. The aircraft was powered by a 225 hp Continental O-470-E. The aircraft was an immediate success and, through the New Zealand Meat Board, an order was placed for 100 aircraft to be supplied in knock-down form and kitsets. The New Zealand agents, Cable-Price Corp of Wellington, contracted James Aviation Ltd of Hamilton to assemble the aircraft in the large wooden hangar now occupied by Pacific Aerospace Corporation.
Fletcher Aircraft Corporation actually only ever assembled 4 complete Aircraft: the prototype s/n 001, s/n 007, s/n 089 and the first FU-24A dual s/n 102 (although this was first built as a FU-24 single control). Of these four, three eventually came to New Zealand. S/n 089 went directly to Uruguay in 1963 and is the only Fletcher FU-24 ever built that has never been to New Zealand.
The first group of aircraft (s/n 2-52) were allocated the aircraft registrations ZK-BHA through ZK-BIZ in 1954. The first aircraft to he completed was ZK-BHE (#6), flown on 16 February 1955 and delivered to Wanganui Aero Work Ltd, which had placed an order for six aircraft. The second aircraft was ZK-BHA (#2), delivered to Aerial Agriculture of Hastings. The first thirteen aircraft were delivered partially completed and were basically the same as the New Zealand aircraft, except semi-flush rivets were used giving all metal-surfaces a near smooth appearance. The forward fuselage incorporated the engine exhausts within an augmentor tube on both sides of the cowling (similar to those fitted to the Auster Agricola). The ailerons were a similar pattern to the flaps. The bulged ailerons came in the late 1950s and the horn balanced conversions in the late 1960s. The last of the part-assembled aircraft was ZK-BHK, flown on 26 June 1955 and delivered to Southland and Otago Aerial Topdressing Co Ltd of Dunedin, while the first completely assembled aircraft was ZK-BHL (*44), which was flown on 10 August 955 and subsequently delivered to Aircraft Service (NZ) Ltd of Auckland. Of the original batch of aircraft, number 7 was retained by Fletcher Aircraft and this became N6506C first flown on 8 February 1955. Built as an agricultural aircraft, it was used as a test bed for engine and airframe upgrades until sold to James Aviation, fitted with a geared Continental GIO-470A developing 310 hp, becoming ZK-CQB in May 1966.
Production continued through 1956 and a further batch of registrations were allocated, ZK-BOA through ZK-BPZ. However, production slowed at the end of 1957 with the last aircraft, ZK-BOL (s/n 64), completed and flown on 26 November 1957.
As Fletcher had allocated 100 serial numbers to New Zealand assembly, number 102 was completed and flown in June 1955 as N6507C. In 1962 it was converted to a Utility version and fitted with dual controls. Two months later it was sold to New Zealand and became ZK-CCT.
Air Parts (NZ) Ltd was formed in 1957 by local operators and they took over the agency of the Fletcher FU-24 aircraft. The first aircraft registered was ZK-BVA (s/n 66) and was assembled at Mechanics Bay by TEAL, barged to the upper harbour and flown at Whenuapai on 1 December 1957.
The original design of the cowling was a round open design, but from ZK-BIJ onwards the front had been replaced by a simple flat panel manufactured in Hamilton with air intake holes on either side of the propeller. Alarger air scoop on the top of the cowling had replaced the intake on earlier aircraft. At the end of 1956, Continental had introduced the 240 hp O-470N and this was fitted to the American registered aircraft in November 1950. The first aircraft in New Zealand fitted with this engine off the production line, ZK--BIX, was flown on 13 April 1957.
The 240 hp aircraft later became known as “Mark Ones” and some of the later TEAL aircraft (ZK-BPY, -BPZ, -BWD and -BWV) had been registered as FU-24Ns, meaning an O-470N was fitted. All earlier aircraft were progressively re-engined and modified to Mk I status at major inspections or overhauls. The 225 hp motors continued to be used as short-term spares.
James Aviation assembled the last Mk I, ZK--BYC (s/n 78), with an O-470E motor but soon changed to an O-470N. ZK-BYC first flew on 19 July 1961. The last aircraft known to have the O-470E was ZK-BIP and made its last flight, so powered, on 25 October 1963 before being converted to Mark II status (260 hp). The last flight of a Mk 1, 240 hp Fletcher was made by ZK-BHC on 12 January 1970 after being sold to Wanganui Aero Work.
When the first aircraft arrived in New Zea-land in 1954 the Fletcher still had an open cockpit. The large hatchway was replaced with a smaller door located on the right-hand side, immediately behind the hopper, giving access to a bench seat for two passengers, or access for the engineers during maintenance. The small door was hinged at the top but aircraft assembled from kits brought in by Air Parts NZ Ltd (Cable-Price Corp) were fitted with a door hinged at the side and were only fitted to aircraft with the original 27-ft3 hopper. The aircraft kits were assembled by James Aviation at Hamilton, starting in 1955, and all were completed as topdressers, first flown on 24 September 1954.
Once orders for hopper-fitted topdressing aircraft were fulfilled, the agents turned to thoughts of selling the aircraft as a utility version. The aircraft chosen was ZK-BIL (serial #39). Completed as a topdresser, it had the hopper removed at Hastings and modifications done by Temple Martin, modifications that included fitting a hatch with square windows in late 1956. As a passenger version, ZK-BIL was on display at Palmerston North in November 1956 during the Agricultural Aviation Airshow.
The next change in the development of the Fletcher FU-24 occurred in 1961 with the introduction of the Mark II model. The front of the cowling, which could he easily removed during checks, was redesigned to incorporate the new 260-hp Continental IO-470-D. The first Mark II FU-24 was ZK-CAY (#79), which first flew on 18 January 1962. Like ZK-CAZ, it was fitted with a 240 hp Continental and short airscoop on the top of the cowl.
ZK-CBA, fitted with the new 260-hp motor and, for the first time, without the airscoop (as were ZK-CBB, -CBC and -CBJ), first flew on 1 June 1962. The James Aviation aircraft that followed, ZK-CBD, -CBE, etc, with short scoops had 240 hp motors installed. The next new aircraft built, ZK-CDZ, was fitted with the 260-hp motor had a long airscoop on the top of the cowl which became the standard for this version. Within three years, other than ZK-BHC which was in storage, all remaining Mark I aircraft had the Mark II cowling fitted; primarily for ease of maintenance. The shortage of 260-hp motors saw some new aircraft fitted with 240-hp motors, or the O-470-M, an upgraded O-470-G, which delivered 250-hp. Around 1964 ZK-BXZ was fitted with a 310-hp geared Continental GIO-470A. ZK-COB (#7) arrived from the United States in 1966 with a 310 hp engine but this was removed in July 1967. In 1963 another batch of components was produced in California and one aircraft was retained, #89. This was completed as N9636Z and flown to Uruguay in April 1963.
By 1964 kitsets were in short supply, and James Aviation set about building “bitsers.” The first of these aircraft, ZK-CLA (#JAL/FU-1) first flew on 4 December 1964. Five more aircraft followed with the last being ZK-CPY, flown on 31 August 1960. ZK-CMG (#111) was the last to fly at Whenuapai as no. 112, ZK-CMH, first flown on 2 August 1965, was finished at the new Air New Zealand workshops in Auckland. The last aircraft to be assembled by Air New Zealand was ZK-CMO (#119), finished on 23 February 1966 and delivered to James Aviation Ltd. Among this batch of aircraft were two dual control FU-24As, ZK-CMI (#113) and ZK-CMK (#115), which were both completed in 1965.
A new Continental motor, the 285-hp IO-520-A, became available in 1965 and the first new aircraft such fitted was ZK-CML, flown on 16 December 1965. ZK-CMM was assembled by James Aviation Ltd for Air Parts (NZ) Ltd and it was delivered to Central Aviation Ltd. The James Aviation conversions with this motor had the aircraft fitted with three-blade propellers and James Aviation had also fitted three-blade propellers to some 260-hp Fletchers (identified by their long airscoop).
The first completely New Zealand built example built by Airparts (NZ) Ltd in 1966 was a 300-hp variant delivered to Wanganui Aerowork. Prior to that Aircraft were assembled from detail parts produced by Fletcher Aircraft Corporation in the USA.
In 1966, Air Parts began producing the Fletcher FU-24 with ZK-CRF (#121) being the first, flown on 24 June. This aircraft was fitted with a 285-hp Continental IO-520A and later, the 300-hp IO-520-F became available. These engines were also fitted to older aircraft and could be identified by the short airscoop, the same fitted to the 240-hp aircraft. The 300-hp version also had a pressing on the front of the cowl giving clearance to external parts at the front of the Continental IO-570-F.
The all-up weight (AUW) for the 225-hp Fletcher started out at 3,200 lbs and had increased to 3,500 lbs for the 240-hp conversions and then up to 3,910 lbs for the new 240-hp models. With introduction of the 285- and 300-hp aircraft the AUW had reached 4,470 lbs.
The last new 300-hp Fletcher FU-24, ZK-DAJ (#154), was test flown on 23 December 1969 and delivered to Australia becoming VH-SFL. One final change for 300-hp aircraft appeared in late 1970 when the oil cooler was removed from the front of the engine and mounted on the airframe below the engine cowling.
In August 1962, N6507C, in the United States, had the hopper removed and was fitted with dual controls, and also with four passenger seats and windows. When offered for sale it was bought by James Aviation Ltd and in February 1963 was in service as ZK-CCT, the first dual-controlled training Fletcher topdresser. All dual control models being designated FU-24A.
Air Parts (NZ) Ltd obtained the world manufacturing rights in 1965 and took over production in 1966 and was well under way at Hamilton when a Queensland rancher, Ewan MacKay, ordered a 300-hp Fletcher which was flown to Australia in September 1967. A talented Sydney engineer by the name of Bill Smith designed and converted the Fletcher into a real utility aircraft by fitting a three-foot by three-foot door on the left-hand side of the fuselage. The AeroSmith doors are recognised by being hinged at the top. To compensate for the removal of fuselage formers, an extra skin was added around the door and an angle section was riveted along the fuselage and under the door sill. As ZK-DCM, it was first flown in December 1967.
Several other door conversions were done in Australia and these were designated FU-24A/ls by the Australian Department of Civil Aviation. In New Zealand, James Aviation also converted five surplus topdressing Fletchers in 1968 using the AeroSmith door.
Air Parts (NZ) Ltd completed a brand new Fletcher FU-24, ZK-CVW (serial #139) as a utility version and was first flown on 12 July 1968. This aircraft was fitted with a door hinged on the left-hand side. In November 1968, ZK-CXZ (serial #143), another Fletcher, flew designated an FU-24-872. This was a utility with a hopper. This aircraft was flown to Australia and was eventually sold as a topdresser.
The first number of the code was to indicate the engine fitted: 1XX for the O-470E, 2XX for the O-470M or O-470N, 3XX for the O-470G, etc. The second number, XOX indicated the basic production, X1X was referred to the 240-hp Mk.I, X2X the Mk.II, X3X indicated an AUW of 4,470 lbs, X4X and X5X were projected versions and X6X was allocated to the turbines of 6,000 lbs AUW (but which, in fact, reached 5,450 lbs). The third set of numbers was to represent versions of each model, XX 1: NZ agricultural, XX2: NZ utility, XX3: Australian agricultural and XX4: Australian utility.
The next major development in the early 1970s was the introduction of the FU24-950 Series, using the 400 hp Lycoming IO-720 engine. (This engine change was first carried out and approved in Australia by Pays Air Service, using Space Development drawing number 5090.) The MAUW was also increased for the FU24-950 variant to 4860 lbs in accordance with Air Parts Service Bulletin AP55 (Parts A, B and C).
The 400-hp FU-24 known as the "950" was actually first developed in Australia by Airparts (NZ) Ltd's Sydney branch. This prototype was then abandoned in favour of another being developed by Pay's Air Service in Scone NSW. The PAS 400 was converted from 300-hp variant s/n 136 and first flew as a 400-hp in February 1970.
400-hp FU-24s were operating in Australia, all modified from 300 hp variants when the first factory example s/n 155 named FU-24-950 was produced in 1970.
This variant was very successful and became the standard production aircraft. In addition most existing FU24 aircraft were upgraded to this configuration under Supplemental Certificate of Type Approval Number SA-3 and re-designated FU24-950M.
In April 1970, Air Parts (NZ) Ltd produced the first 400-hp Fletcher, ZK-DBF. By using the unused number 9XX for the Lycoming IO-720A, and the unused X4X for an AUW of 5,430 lbs.
Air Parts (NZ) Ltd continued building the 400-hp Fletcher FU-24-950s fitted with the 37-cu.ft fibreglass hopper. Ten aircraft were built with no access door except a removable panel under the fuselage.
In November 1971 ZK-DGE was registered as an FU-24-954, an agricultural model with an Air Parts door. This fuselage was set aside and another assembled along with three other kits. ZK-DHD (serial #169) was the first to be completed and it was fitted with a “half-size” door at 30” x 17.5” hinged at the top. This aircraft first flew on 17 February 1972. ZK-DGE was completed as a normal FU-24-950 and flew in June 1972.
The airframe with the large door became ZK-DHO (serial #171) flew on 26 September 1972 and was registered as a FU-24-950. In August the following year, the aircraft was damaged beyond repair near Stoke. The title FU-24-954 would have required another type certification process, so any aircraft produced, with small or large doors, were FU-24-950s but in-house the large door variety were known as -954s.
The model name 954 has two variations: firstly, an in-house type upgrade by NZ Aerospace Industries of all additions and modifications to the airframe and wing to include the door modification within the type certificate and, secondly, the post-954, the customer production model “954” with major additions to the airframe and wing. The FU-24-954 (post-954) production model first appeared in 1978, featuring a number of new additions. Externally, a new more streamlined cowling, a cargo door built into the airframe, thus reducing the empty weight, and the wing had modified aileron tips and vortex generators on the outer wing panels. The first Cresco was nearing completion at the same time and both aircraft shared the outer wing panel and cargo door modifications. The major change in the cockpit was the rudder pedals and these are only fitted to “production -954s.” The -954 was also fitted with a 43-cu.ft fibreglass hopper.
In 1973 Air Parts (NZ) Ltd and Aero Engines Services Ltd merged and a new factory was built at Hamilton airport. The new company became NZ Aerospace Industries Ltd. Production of the Fletcher FU-24-950 continued with the original factory being used for component manufacture. When Aerospace Industries completed the upgrade of the Fletcher modifications both factories had completed a total of 89 400-hp FU-24-950 topdressers including 14 aircraft fitted with the large cargo door. In 1977 the Fletcher FU-24-950 ZK-USA (serial #240) was flown to the United States. A company called Frontier Aerospace at Long Beach, California, was set up to assemble aircraft, while at home NZ Aerospace Industries set about upgrading all modifications into one certificate, and this became the FU-24-954, although the aircraft being built were still physically FU-24-950s. ZK-EGY (serial #247) was the first to be registered as a basic FU-24A-954, a dual control aircraft with a large cargo door. The air-craft was assembled to knock-down standard and was sent to the United States. Several aircraft followed, both as kits and knocked down aircraft. A new series of kitsets were allocated #3001 onwards and four were completed and sent to the USA. These were basic FU-24-954s with large cargo doors. They all returned to New Zealand and two were assembled by Aero-space, ZK-EUB (#3002) and ZK-EUE (#3003) and were fitted with post-954 engine cowlings and outer wing panels. ZK-EUB went to Australia and became VH-EUO.
Production of the FU-24-950 continued until s/n 248 in 1978 when it was replaced by the FU-24-954. The prototype FU-24-954 was actually s/n 247 and it was exported to the USA where it languished unassembled for some years until it was returned to New Zealand and flew for the first time in 1988 at Wanganui Aerowork. The first FU-24-954 to be completed and fly in New Zealand was s/n 250, which first flew in May 1978. Aircraft were being built out of s/n sequence at this time, as s/n 249 did not fly until May 1979.
The last FU-24-954 was s/n 257 so numerically it was the smallest variant built with the exception of the sole FU-24-872, and the three turbine variants built in the late 1960s.
Next came the final factory variant named FU-24 post 954 with s/n 258. Production of the post 954 continued, albeit sporadically, until s/n 297, which flew in May 1992 when production was halted in favour of the 08-600 Cresco, (which itself had been in sporadic production for some 10 years). Of the final 10 FU-24 post 954s built the first five went to Thailand and the final five to Syria.
There is confusion as to what is an FU-24-954 and what is a FU-24 post 954. The FU-24-954 is identical to an FU-24-950 but with a large Cargo Door. An FU-24 post 954 had a revised appearance including new Cowlings, Aileron fences, changed Rudder Pedals and many other refinements over an FU-24-954. What is generally accepted as an FU-24-954 is actually an FU-24 post 954.
In February 1996 VR-EUO flew as the first Garrett-powered Stallion, or FU-24A/6, which was approved in New Zealand under CAA STC 98/21E/13. At Scone, New South Wales, AirPasture flew the Stallion - the turbine Fletcher FU-24A16 VH-EUO. This aircraft was fitted with the Garrett TPE331-6 and first flew on 21 February 1996. The addition of two extra fuel tanks located in the leading-edge of both wings now gives a total Jet A-1 fuel capacity of 500 litres (123 usable litres per tank), which compliments a safe operational endurance of the standard two hours, thus the turbine burns about 200 litres per hour. Fuel distribution is from the four wing tanks into a header tank positioned between the main tanks, just forward of the hopper box, and then to the power plant via an emergency cut-off valve. The cut-off valve is operated by the pilot and in-stantly deprives the engine of fuel and feathers the propeller. This conversion used the standard FU24-950 vertical fin but with the addition of a dorsal fin. As part of the CAA approval the design substantiation was reviewed. The designer of the Stallion, Auto Avia Design, stated that “The dorsal fin was solely to improve directional stability – with the longer nose for the turbine engine, the weathercock stability was lacking.”
The Fletcher FU24 has a unique type of vertical fin construction. It is made up of strips of vertical sections with integral edge-stiffeners. There is a substantial rear spar, which the whole fin structure effectively cantilevers off. The front fin attachment is a single pin-joint.
In the original FU24 fin design there was one internal rib. When the aircraft was first converted to turbine power as the FU1060, with increased speeds and operating weights (and hence design loads), the vertical fin had to be strengthened. This was done by fitting additional internal ribs and associated external straps. This fin design was carried over to the FU24-950, with some minor detail changes.
Serial #270 was a kit sold to Australia and was registered VH-UJP as an FU-24A/4. In 1994 the very last 300-hp Continental IO-520-F Fletcher FU-24 was converted to a 300-hp Lycoming IO-540S1A5. VH-SFL is designated an FU-24A/5.
Late in 1993 two North Island ag companies, Fieldair and SuperAir, took different paths with the installation of a V8 motorsport engine on an FU-24. Fieldair chose a small-block 402 Chev engine, with turbo-charging, to develop 550-hp. The engine was fitted to the FU-24A-954 ZK-EMO and ran in late 1994, designated an FFU-24. Two years later the project was abandoned. At Hamilton, Super Air embarked on the motorsport engine path with a 640-cubic-inch 500 hp V-8 Ford engine. Super Air Ltd was the first applicant and established the principle that the CAA would accept a significant increase in power (37%) for the take-off condition with a 5 minute limitation, with no changes required to the aircraft flight envelope. This was running in ZK-BHG in 1995. The project has been beset with a number of problems; nothing major and but the company has proceeded with development on a low-key basis. A locally manufactured gearbox allowing reverse pitch was installed and the aircraft first flew on 23 January 2000. Neither project was taken forward to the certification phase.
The first modern New Zealand turbine conversion was by Super Air Ltd as the Walter Fletcher, using the Czech Walter M601D-11NZ engine. This (ZK-EUF) first flew on 4 October 1998 and some 23 conversions have since been completed comprising FU-24-950, -950M and -954 airframes. The standard FU24-950 vertical fin is used.
Super Air then produced a Pratt and Whitney Canada PT6 powered version with a stretched fuselage, which resulted in a configuration externally very similar to the Cresco. Again there was no change to the vertical fin.
A very similar stretched PT6 turbine conversion was produced by Flightcare Limited in 2005, as the FU24-550 Crusader. This aircraft also used the standard FU24-950 vertical fin, but with the addition of a dorsal fin.
2000 saw Wanganui Aero Work modify an FU-24-950 with a Cresco centre wing section and added a Lycoming LTP-101-A1A 550 shp engine, with a Hartzell HCB3TN 8 ft 6 in prop out of a Cresco, with the “Fletcher Falcon,” ZK-LTF, first flying on 6 April.
Factory assembled examples were serial numbered 001 through to 297, 2001 and 3001 through 3003.
All re-powered conversions of the FU24-950 have continued to use the standard FU24-950 vertical fin Part Number 240340, with no changes other than in some cases the addition of a dorsal fin. This fin was originally approved for the FU1060, which had a similar engine power to the modern turbine conversions. Two of the three original turbine conversions using the Part Number 242341 vertical fin had successful service lives of up to thirteen years, with no reported structural problems.
Piston engines have not been forgotten though. To get high altitude performance, Advanced Aero Engineering Ltd converted a dual FU-24A-954 with a 350-hp turbo-charged Lycoming TIO-540. Known as the “Magnum,” ZK-EMK first flew at Masterton on 19 June.
In 2001, Turbine Conversions approached Pacific Aerospace Corporation with the idea of using the “08” Cresco plug for an extended Fletcher (TOFURA). The Fletcher selected for the conversion was #277, a 1980-built FU24-954 registered ZK-EMW. The aircraft was completely stripped at the end of 2001, and overhaul and re-assembly began on 8 January 2002. The wing was overhauled and extra fuel tanks installed the same modification made to the Walter conversions. Once the forward and aft fuselage sections were over-hauled, the 18-inch “08” Cresco panels were inserted. An all-new, one-piece 60 cu.ft hopper manufactured by Profession Fibreglass arrived about the same time as the wing was mated with the new fuselage. The engine mount is the same as the Walter conversion except for a few modifications as the PT6A-11AG engine is positioned two inches further forward. The same air filtra-tion and induction system are used and the cowling, also made by Professional Fibreglass comes from the same mould as the Walter but has minor modifications for exhaust outlets and air filtration scoop. Although the PT6A engine sits two inches further forward on longer engine mounts, the cowling is exactly the same length as the Walter configuration. The fuel system is also identical to the Walter version. The undercarriage remains unchanged with the exception of an extension block on the nose wheel piston and the fitting of heavy-wall Cresco cylinders to the main undercarriage. ZK-EMW was test flown by Kevin Young at Hamilton on Thursday, 23 January 2003.
Engine: Lycoming IO-720-A1A, 400 hp
Wingspan: 42 ft 0 in / 12.81 m
Length: 32 ft 9 in / 9.98 m
Cabin length: 10 ft 5 in / 3.18 m
Max cabin width: 4 ft 0 in / 1.22 m
Empty weight equipped: 2616 lb / 1186 kg
Max payload (ag): 2320 lb / 1052 kg
Normal max TO weight: 4860 lb / 2204 kg
Special TO weight: 5430 lb / 2463 kg
Max cruise: 106 kt / 122 mph / 196 kph
ROC SL: 630 fpm / 192 m/min
Service ceiling: 16,000 ft / 4875 m
Range max fuel: 382 nm / 440 mi / 708 km
Accommodation norm: 1 pilot, 5 pax
Accommodation norm: 1 pilot, 1 pax
FU-24 300 hp