LOSS OF THE AIRPLANE FACTORY SLING DURING SPIN TESTING!

At midday on Saturday 13 February 2010 ZU-TAF, The Airplane Factory Sling in which the company owners, Mike Blyth and James Pitman, circumnavigated the globe during 2009, crashed into the sea just off the South African Kwa-Zulu Natal coast. While the staff and owners of The Airplane Factory are devastated to have lost their production prototype aircraft, they believe that comprehensive spin testing of aircraft is an important aspect of an aircraft development program, notwithstanding that it is inherently risky. ZU-TAF was The Airplane Factory’s second prototype aircraft and has precisely the same aerodynamic characteristics as the production aircraft which the company sells. The only structural differences between ZU-TAF and the production Sling were the sealing off of certain sections of the wing to increase the number of fuel tanks, the marginal beefing up of the composite main gear, making the joysticks removable in flight, and the removal of a cross brace behind the seats to allow the pilots to lie flat on long flights. In all other respects the round the world aircraft was the same as the production LSA Sling. During July 2009 ZU-TAF was flown 18 000km (9 700 nm) from Johannesburg , South Africa , to Oshkosh , Wisconsin , westwards over a 10 day period. The longest leg included a 4 050km (2 200 nm) leg over the Atlantic Ocean . During August the aircraft was flown 28 000km (15 100 nm) back to Johannesburg , also westwards, over 23 days. The route included Los Angeles , Hawaii , the Marshall Islands , Micronesia , Indonesia , Malaysia , Sri Lanka and the Seychelles . The aircraft performed flawlessly during the entire circumnavigation. In fact the only maintenance related issues encountered were a faulty fuel tank drain valve and a crack in one of the supports for the electric propeller pitch motor. Back in South Africa ZU-TAF flew another 200 hours from September 2009 to January 2010. These hours included numerous long cross country flights (sometimes in IMC), demonstration and test flights. The company owners and many other experienced pilots who flew ZU-TAF believed she had the most balanced, safe and pleasant handling characteristics of any aircraft they had ever flown. In view of the aircraft’s excellent performance well beyond 600kg (1 320 lbs) a decision was also taken to certify the Sling not only in accordance with the ASTM LSA standard, but also to 700kg (1 543 lbs). (She commenced each of the long legs during the circumnavigation at 960kg (2116 lbs)). This required further flight testing which could be performed at the same time as spin testing, which had not yet been completed. The company therefore arranged for a qualified test pilot, Carlos Garcia-Cabral, and his colleague, Shaun Fraser, to perform spin testing from Virginia Airport , Durban , on the weekend of 13 February 2010. A progressive spin program was agreed incorporating discretion for the pilot to determine appropriate incremental steps and safety requirements. During the first spin test flight the aircraft proved to recover immediately and predictably from incipient, one turn and one and a half turn spins, using conventional control inputs. The test pilot accordingly requested that the CG of the aircraft be moved backwards to its midpoint, the fuel quantity be increased and a second test pilot fly the next test with him so as to monitor and record the recovery with a film camera. The aircraft was lost during this follow up flight. The pilots reported after the accident that in the new configuration the aircraft also initially recovered immediately and predictably from incipient, one and one and a half turn spins, including spins in which incorrect control and throttle inputs were intentionally used. The recovery characteristics of the aircraft from these spins led the pilots to believe that they could safely test it to two full turns, which they accordingly did. Following successful recovery from initial two turn spins, in the final spin of the flight the spin flattened, and notwithstanding their efforts, the pilots were unable to recover the aircraft in the height available. The agreed spin test protocol provided for the implementation of emergency procedures at 4 000 feet agl. At that altitude the engine was accordingly cut and the ballistic parachute deployed. Although the ballistic rocket fired, it failed to pull the packed chute through the parachute cover. It would appear that the weight of the chute and its shape was such that the force required was too great to breach the cover, which subsequent consideration suggests was fastened too firmly. This design is being addressed and testing will be performed. Notwithstanding the failure of the ballistic chute, both pilots were able to exit the aircraft cockpit and deploy their emergency parachutes. Unfortunately the force with which Carlos Garcia-Cabral’s canopy deployed caused him to suffer whiplash which fractured his C2 ad C3 vertebrae. He received excellent medical help and fortunately appears to have suffered little or no nerve damage. He is expected to make a full recovery. Following the pilots’ exit from the aircraft it recovered from the spin and hit the sea, approximately 200m offshore, in a gliding turn to the right. Although the aircraft remained intact and floated for approximately 2 hours, the search and rescue services did not attach a rope to it before it sank below the surface. The ocean current subsequently moved the aircraft and some 6 days later it has still not been found. Accidents of any kind result in reflection and reconsideration. The Airplane Factory is currently awaiting the full written reports of the pilots. The company will also continue to consider all advice and input from experts as well as members of the public. While the accident constitutes a significant loss, both commercially and emotionally (particularly for Mike and James, who flew ZU-TAF around the world), the Company is proud to be engaged in a development program that aims at the highest possible standards. The Company’s commitment to comprehensive testing can only have the consequence of protecting members of the public who use its products. The Airplane Factory expects to have a new aircraft flying by mid March 2010 and intends to continue to develop and sell the best, safest and most comprehensively tested aircraft available. We thank all those from whom we have received messages of support over the past week. The Airplane Factory Mike said, “If one is going to lose an aircraft, I suppose that the best possible way for it to happen is in testing aimed at ensuring the final safety of members of the public. The flight formed part of a structured test program, which was why both pilots were qualified test pilots wearing parachutes. No member of the public is likely ever to be placed in the position in which the pilots found themselves.” James said, “While we are obviously devastated to have lost our prototype aircraft we are proud to have been testing it to its outer limits. It was because the plane performed so flawlessly during initial spin tests that it was tested further. We’re just glad no-one was seriously injured and The Airplane Factory will continue to ensure that its products are tested and proven to the highest levels. In fact, the test pilot who was flying the aircraft when it crashed had said of the Sling just days before, ‘If someone kills themselves in this aeroplane, then they’ve got a death wish.’ It’s precisely because TAF is willing to perform this kind of testing that the Sling is as safe an aircraft as it is.”

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