The creation of any plane is a long and complicated process, the result of the joint efforts of numerous departments and divisions. The aviation complex of Ilyushin includes many laboratories for aircraft testing. Structural tests are among the most important ones. Today we are going to see how and where such tests are done.
When static tests are done, a load is placed on plane components that exceeds the operating load by 1,5 times. The load on a wing during a flight can exceed 1000 tons. The operating load is actually equal to 67% of the design load, but actually such loads never occur during a flight.
A wing, as the most vulnerable part of the whole construction, is subject to testing with a load equal to 120% of the design load.
The Il-76TD plane you can see above was made in 1988, it logged 2500 hours and was finally given to the design bureau in 1994 for testing new engines, PS-90’s. No engines were mounted in the aircraft though, so instead it became a vehicle for endurance testing.
The Il-76 is intended for 20 000 flights, but to provide such characteristics to the plane they had to implement a full suite of endurance and strength tests in the very beginning, and keep testing the plane to prolong its service life.
Such a lab is exactly the place where such tests are carried out.
The chassis of the plane is dismantled, and the the vehicle is left hanging on a special suspension that provides dozens of tons load on the carious elements. The autotrack system allows stabilization of the suspension and provides the required flight conditions. On the left wing semispan are pylons for the standard D-30 engines, and on the right are pylons, reinforced structural elements and mount points for PS-90 engines, which are heavier and more powerful than D-30 ones.
To determine the service life of a plane, they count on 3 – 4 hour flights and an operational lifetime of 20 – 25 years. To further prolong the basic service life they start implementing additional tests that may last for years. Thus, they managed to prolong the service life of Il-76’s with D-30 engines to 10000 hours…
Programmed flight usually lasts twenty minutes and is carried out with a full load on the structural elements of the wing and fuselage. They sum up the load from all cylinders for a general calculation. In the final stage of testing they increase the load on wings to imitate landing.
If any damage is revealed during testing, they stop to repair the damaged unit, then testing is resumed. Damage to the structure may be revealed by both visual and instrumental methods.
The longer the service life of a plane is, the more restrictions are imposed on its operation. Thus, they may restrict flights due to weather conditions or replace passenger flights with cargo-carrying ones.
Such a ring creates loading on the floor.
The place of a navigator and some more loading rings.
Wiring and sensors for the measuring instruments.
View of the wing from the porthole, entangled with brackets, wiring and beams.
If any cracks are revealed, they are eliminated with stuck-on methods (by means of so-called “stoppers”).
The Il-76 is still widely used in Russia and abroad. So endurance and strength testing will continue.
Pylons for PS-90 engines.
The wing is entangled with counterweights and levers, all together comprising a rather complicated system.
From here an operator controls the testing programs. The hangar has two cabins like this.
Another plane – a wooden, full-size mockup Il-96-300, created for the analysis of cabin configurations.
Cabin of the mockup.
Almost like real!
The cabin is rather spacious.
And this is a five-seat Il-103, it has already undergone all types of testing.
General view of the laboratory.