Airborne Microlight Aircraft, microlights, trikes, ultralights, ultralight trikes and hang gliders

XT STREAK certification tests.

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Engine mount testing.
This test applies worst case loading to the engine mount, where the loads are reacted through the airframe.
6 g vertical 4472 N (1005633 lbf)
torque load 736Nm (543 ft lbf)
Thrust load 3923 N (882lbf)
Additionally all flight loads, ground loads and crash loads are tested on the engine mount. The engine mount and other items of mass are tested for restraint at 15g deceleration. The engine mount was tested to a forward load of 11768N (2646 lbf). The XT passes all of these tests without any permanent deformation.

Throttle test.
The hand and foot throttle are connected to a trike base that is out of frame in the picture. Loads are applied simultaneously to the controls, where the test loads were:
Combined load on throttle splitter and carburetors 1334N (300 lbf)
Independent loads were applied to:
Hand throttle 363N (82 lbf)
Foot throttle 1393N (313 lbf)
No damage occurred to any of the components including the levers, cables throttle splitter or carburetors.

Propeller Testing
The propeller is tested by over speed, so that in the ultimate load test, the centrifugal forces are 2.3 times the in service loads.
The propeller is driven by a Ford 302 Cleveland with open carby and exhaust. Maximum power is approximately 200hp (boosted by using avgas). The propeller demonstrated an ability to consume all of this power.
Centrifugal loading during the ultimate load test was 57220 kN (6.43tn force)
The propeller was undamaged following the test. Pictures cannot do this test justice, with the propeller tips operating at Mach 0.97 (320.3 m/s) and open exhaust engine it was quite an experience as the witnesses attest to.
Quoting Paul Mollison of AirBorne, with regard to the limit load and ultimate load over speed testing experience: ... In the first test the noise of the unmuffled V8 was really impressive for a while but after 15 minutes we were really happy to shut it down and give our ears a break. For the second test the roar of the V8 faded into the background as the prop loaded up. As we approached the test speed the noise, the quantity of air being moved and the vibration of the whole set up was physically confronting. The sign to shut it down after the six count did not need repeating. This was one severe test, which left us in no doubt of the structural integrity of the prop.
Les Bollenhagen of Bolly Props said
“ It was quite an experience, I can tell you. The ground was shaking like you wouldn’t believe, all that noise and energy tells you that it (the propeller) is really doing something. Coming out of the test with a propeller in perfect condition gives you an awesome amount of confidence in your product. Following such a successful test, all the trials and tribulations of building the test rig, which in itself is a huge job, are soon forgotten, and are replaced by a big smile”
The propeller and engine combination is also required to demonstrate a safe history of operation in the aircraft.

Nose wheel test & casting factors.
Additional factor of safety of 2 is applied to casting components such as the wheel rims and cross bar haul back catch. On this nose wheel test the vertical and side loads on the front wheel are doubled for casting factor and are applied simultaneously using an appropriate test angle. Ultimate load test was passed at 1112kg 2452(lbf), the wheel was tested all the way to 1453kg 3203 (lbf). Following the test the wheel was bent but functional.

Front wheel energy absorption, front impact test
The front wheel and undercarriage are tested for ability to absorb energy in a front impact. The trike base is loaded to MTOW and driven into a brick wall. The ultimate test is conducted at 8.4 km/hr kph, demonstrating an ability to absorb 67% more energy than required by the design standard.

Wing load test, limit load 4g.
Bags loaded with steel are placed on the inside of the sail top skin. Test witnesses are scrutinizing the load according to the test plan.

Positive limit load test.
After the loading is checked, the sail is closed and additional loading is applied to the undersurface. A digital level is set on the keel, the wing is tested at an angle of attack that loads the space frame in a representative manner. The wing is shown clear of the ground and is balanced at the test angle. Permanent deformation is not permitted at limit load.
The total loads applied to the Streak wing are:
Limit load is 16426N (3693lbf, 1.85 ton)
Ultimate load is 24517N (5512 lbf) (2.76 ton)At Ultimate load the testing personnel confidently walk around the structure and get video footage before lowering the wing. Only three seconds of ultimate load application are required without failure. Permanent deformation is permitted at ultimate load so long as the structure holds the load without catastrophic failure. The Streak structure is remarkably strong and withstands the test sequence including ultimate loads with remarkably little damage.

Limit and ultimate loads are applied for both positive and negative load cases.
The wing is loaded to a positive lift distribution that would exist for the flight envelope at maximum manouvering speed and another lift distribution for dive speed. The wing load test sequence consists of 6 separate tests.

Streak wing positive ultimate load test.
Representative of ultimate load at dive speed. The inside of the sail holds two thirds of the total load. Total load applied is 24713N, (5556 lb, 2.78 ton)

Streak wing negative load test
The wing is loaded to a 3g negative ultimate load. The wing is suspended by the keel bracket protruding through a hole cut in the sail. The load applied here is 1255kg (2767lb 1.38 ton).
After this test the engineers decided to have some fun, the structure had not broken so they did not know how much reserve strength the structure really has. In the next informal test, the structure took 120% of the required ultimate load and still the structure did not fail. In the industry it is common practice to make kingposts as short as possible to just pass the negative load test. The Streak passes with plenty of room to spare.
The Streak wing in its certified form has not failed catastrophically in any of the tests positive or negative. The structure has survived all of the testing without failure.
(no photo provided of informal test.)

Nose catch load test.
The complete nose catch assembly is loaded at the same angle as the nose wires, this nose catch assembly is loaded to loads of:
Limit load 565kg, (1126 lbf, 0.61 ton) which is more than twice the strength required from the fitting according to the design standard.
Ultimate load 1030kg, 2271 lbf, 1.14 ton) which is more than 2.5 times the strength required from the fitting according to the design standard.

Trike base, flight and ground load testing.
Ground reacted loads are being applied to the XT trike base.
Loads can be seen being applied to the mast head, fuel tank, occupants and just out of view is the cockpit load.
The test frame allows the application of multiple large loads to the structure via cables. In this way the structure can be clearly seen through out the test and the loads are safely contained. Loads are applied via dead weights and winch/load cell combinations.
Operators are using block and tackle sets to raise dead weights so that they apply load to the structure. The method is great for safety; as the dead weights only need to be raised just clear of their supports. The operators are clear of the loads and the loaded structure.
Being mindful of the future development of the XT, different engine weights are justified during the test sequence.
Placards are used to show the loads that must be achieved for the validation of the test.
In the same test sequence the wheel supports on the test frame are removed, the mast is connected and the loads are re applied for the demonstration of the in flight loads. It is a well thought out, smooth and efficient process.
The structure passes without permanent deformation.

Test rig set up for 9g forward emergency landing conditions. 2385 kg of dead weights are sitting in the cradles.

9g forward ultimate test, emergency landing condition.
Loads applied are:
Occupant restraint, 1800 kg (3968lb)
Fuel tank 585kg (1290lb)
Oil tank 54kg (119lb)
Engine 710kg (1565lbf) applied by winch / load cell.

Following the test , the only damage was a bend of 2 degrees in the mast another bend in the shoulder belt tang that attaches to the lap belt. This bending is permitted in the Ultimate load test. All items of mass were retained from simultaneous loading. Additionally the occupant restraint was tested using the lap belts only.
There is also a 15g forward engine restraint load applied in a separate test, in which engine mount loads applied are 1200kg, (2646lbf) applied by winch / load cell. No permanent deformation occurred.

Fuel tanks must be shown to be capable of retaining their contents under all of the accelerations given in the design standard. The fluid pressure from the 9g forward emergency landing loads apply the greatest pressure. Applying this using air pressure within the entire tank is very simple and conservative.
The pressure applied is 6 psi. The tank retained the pressure.

Rear wheel wishbone testing.
The structure is attached to rigid mounts, vertical loads are applied to the wheel via hydraulic ram and greased plate. Horizontal loads are applied via winch and load cell. There are multiple combinations of wheel spin up loads, side loads and vertical loads to be tested. Bearings are subject to additional load carrying ability in the design standard. Further justification is provided by analysis, to cover bearing factors.

Fuel and oil lines must be made from fire resistant materials.
The test shown is a calibrated flame impinging on a fuel line containing static water.
The test exposes the hose to the part of the flame at 1100 °C (2012 °F) for 5 minutes. After the test flame exposure, the fuel line must remain flexible and retain its contents at operating pressure.


		Our certification policy: AirBorne Australia has been designing and testing certified aircraft for many years in order to operate in their domestic market and to access other markets through out the world. To access world markets, AirBorne have chosen to justify the design of the Edge XT to the BCAR S design standard. This design standard is currently more widely accepted throughout the world than the Sport Pilot ASTM standard. The BCAR S certification covers a wider, more demanding range of tests so that a compliant design requires little other work to also comply with the Sport Pilot ASTM standard.

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