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."

Below is a post made by Marc Gregson, one of the test pilots who flew the Sling before, on Avcom (South Africa's largest general aviation forum) with regards to the accident that happened over the weekend.

Hi All,

Just to answer a few questions, and clear the speculation...

I did a large amount of the original test flying on the Sling (Did not do the spin tests, however). After many hours of testing, and tweaking on the D6 (first prototype), the "Sling" production prototype, with some major (and minor) improvements, proved to be a really nice aircraft to fly! A nice combination of manouverablity, well balanced controls, and forgiving, predicatable flying characteristics, prompted us to buy a Sling (will be arriving in March )! Second to Mike and James, I have the most hours on the Sling. I have spoken to James in detail, so I am not speculating on this post.

The fact that Mike and James have gone to the effort and expense to put their aircraft through a thorough, and intensive spin testing program, makes me extremely happy and comfortable in the attitude and ideals of The Airplane Factory, and like others have said, shows their commitment to building a safe and reliable aircraft.

Now the facts about yesterday's spin testing, and accident:

The first set of spin tests were done with one pilot, and half tanks (giving a lighter load and forward C of G. Incipient spins were completed left and right, as well as full turn, and one and a half turn spins both ways, and the recovery was normal, and exceptionally good.

The second set of spins were done with full tanks (normal tanks, not long range), and two test pilots, making it MAUW and rear C of G. Again, incipient spins, full turn, and one and a half turn spins were done, left and right, with normal , and again, exceptional recovery.

At this point, the Sling had passed all the requirements for the spin tests!

On the return flight from the second set of spin tests, the Pilots were so impressed with the spin characteristics, that they decided to enter a sustained spin, to find out if the spin stayed stable. Unfortunately, after the second rotation, the nose pitched up, making the spin flatten out, and rotation speed increased. The pilots tried to recover, but once they hit their hard deck of 4000ft, they decided to abandon recovery. They shut the engine, and deployed the Balistic chute. The rocket fired, but the chute didn't deploy properly. They then opened the canopy, and bailed out (they estimated just above 3000ft), parachuting to the beach. One of the pilots cracked a vertebrae in his neck when his chute opened. Once the pilots were out, the aircraft recovered itself (probably due to a now forward C of G), and proceded to crash into the sea in a descending turn. The aircraft floated for about 2 hrs, then sank a few hundred metres off shore, before they could tag it with buoys. They seem to have lost the position of the aircraft after sinking!

The reason for doing spin testing, is to make sure that an aircraft is safe for the pilots who will later fly it. Only good can come from what they've learnt during this exercise. It is sad to lose such an iconic plane (which I loved!), but good that no one was seriously injured, thanks to the excellent procedure and discipline showed by the test pilots!

Bear in mind, that very few of the light sport aircraft around, are actually spin tested, as this is not a requirement for most European certification processes. In fact, a few people that have tested certain LSA aircraft, found them very difficult, and in fact, almost impossible to recover. The vast majority are not spin tested. I appeal to all pilots, to not spin an aircraft that is not approved for spinning. A spin is a complex aerodynamic situation, with many unknowns. If the manufacturer says don't do it... DON'T DO IT. I hope that everyone learns a lesson from this.

James has indicated that they wil be getting another aircraft together soon, which they will do further spin testing on. All in the interest of making an already awesome aircraft, even better!

I am really glad that people are viewing this in the positive light in which it should be seen! I'm impressed.

Fly safe, and enjoy!

Cheers,
Marc

The Mercury newspaper had a bit more in-depth report this morning on their front page
Click here to view the newspaper article

Natal Witness newspaper reported on the accident over the weekend.
Click here to view the newspaper article (142kb)

The Airplane Factory Sling, which flew around the world during July and August 2009 crashed into the sea at Tinley Manor Beach on Saturday 13 February 2010.

Mike, James and the Airplane Factory team are devastated to have lost their round the world Sling, but are hugely relieved that no-one was seriously hurt in the accident. The accident took place when the test pilots, Carlos Garcia-Cabral and Sean Fraser, were doing spin testing of the aircraft. In initial tests the aircraft recovered predictably and quickly. In the interests of testing the aircraft above and beyond the ordinary requirements, and in view of the sterling performance of the aircraft up to the point of the accident, the pilots on board, both qualified test pilots, decided to increase the number of spins before recovery. It appears that at the end of the second turn the spin flattened and the spin speed increased. Unfortunately the pilots were unable to recover the aircraft in the altitude available to them. At 4 000 foot they cut the engine and deployed the ballistic chute. While the rocket deployed, it appears that the inertia of the main chute, together with its surface area against the "relieved hole" rivets in the parachute escape hatch prevented the main chute from escaping. The test pilots were able to exit the aircraft and parachute safely onto the beach.

While the owners of The Airplane Factory are extremely disappointed to have lost the aircraft in which they flew around the world, they recognise that testing aircraft beyond the limits which ordinary pilots will ever have to face is inherently risky. 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. It’s not without reason that the test pilot who was flying the aircraft when it crashed had said of the Sling ‘If someone kills themselves in this aeroplane, then they’ve got a death wish.’ Its precisely because TAF is willing to perform this kind of testing that the Sling is as safe an aircraft as it is."

At the moment we are awaiting more news from Mike & James from Tinley Manor Beach, as they are looking at the possibility of recovering the Sling.

The Airplane Factory's Sling featured on CNN this morning!

Mike Blyth and James Pitman won the the James Gilliland Trophee at the annual Aeroclub of South Africa Awards evening. Congratulations to both of you for a well deserved award!

Mike & James arrived back at Springs Airfield, Johannesburg after flying for 40 days, visiting 13 countries, and covering a distance of approximately 45,150km in the Sling light sports aircraft which they had built with their team at The Airplane Factory.

The Sling 002 test flight was successful with everybody feeling the excitement during the tests. Have a look at the Around The World link for more photos and news.

You can also bookmark the link http://www.airplanefactory.co.za/world to go directly to the Around The World Expedition pages in future.

The apparently endless weeks of detailed drawing and design work are nearing their end and construction proper on Sling 002, the "Production Prototype" Sling which Mike and James are planning to fly around the world, has started in earnest. The wings, standard save for the insertion of additional 83 and 87 litre fuel tanks in each, are nearing completion. In four hours on Sunday and 8 hours on Monday 24 and 25 May 2009 Mike, James and Steve put together the bulk of the rear fuselage. At last there is again something in the factory that resembles an aircraft! We now hope and expect to have Sling 002 ready to fly by the third week of June 2009, at least three weeks before departure for Oshkosh.

Everyone at The Airplane Factory and friends, are working like mad for the 15th July "Around the World" take-off. Rear fuselage now looks like an aircraft.

The modified wings with modified long range fuel tanks on Sling 002 are almost complete.

Test flying of the development prototype Sling is essentially complete, the design of the production prototype having been settled. The development prototype Sling has flown 41 exemplary hours, undergoing various modifications along the way.

Mike, James, William, Steve, Johan and all others involved in The Sling's development are absolutely delighted with the way she flies, every single design objective having been achieved. Others who have flown in and commented favourably on the Sling include Class 1 test pilot, Dave Stock, 2006 World Advanced Aerobatic Champion and Red Bull Air race competitor Glen Dell, SA Flyer editor Guy Leitch and test pilot and instructor, Marc Gregson.

The Airplane Factory has already commenced construction of the production prototype Sling which Mike and James intend to launch at Oshkosh in July this year. How will they get it there? Fly it from Johannesburg of course, and back the other way! See our Round-The-World link to learn more about the planned flight.