Our client, Game Composites, have been liaising with the regulator, the Civil Aviation Authority who is doing the certification for Game Bird 1 aerobatic aircraft and a plan has been developed to damage the airframe and then test it to see how the structure withstands this damage.
This is to replicate what could happen to Game Bird 1 in a real-life situation, for example, if it were to be stored in a hangar and it was to be damaged without anyone noticing whilst inspecting the plane. The testing we’ve already completed has qualified Game Bird 1 for 30 years of air worthiness certification, but with the damage testing we are going to do, this will help further help the plane gain it’s certification.
Game Composites have been on site whilst we have been damaging the airframe. There are seven points around the plane which are to be damaged from different heights and at different energies.
To do this, we fixed a ball into a bag and tied it to a rope and attached it to a crane over the aircraft, all very high tech at the Advanced Structural Testing Centre! Hovering the ball over the targeted point and graduated the string in metres meant we knew how high up we were suspending the ball to drop it onto the marked targets on the airframe.
Damage has been caused on the tail stabiliser and the wing and we then proceeded to run a few hundred fatigue testing cycles. Unfortunately but we got some rather unpleasant and unexplained noises. After a little bit of thinking about things we realised that when heating the airframe to 72 degrees for the ultimate test we had probably baked the grease off the wing pins and the engine bracket interface pin – the joints were running dry!
We were also concerned that we have got a little bit of movement in the engine mount, because over a period of time during testing it has elongated the holes in the composite material forming the aircraft. Not a lot, but enough that the bracket it moving and creating noise. So today we have taken that load bracket out and Game Composites are going to do the repair on these holes by filling them in with resin and putting the bolts back in. Then it will set and take all the play out.
We have slid the big bolts back in the wing spar to clean them up, add a little more grease, and then slide them back in. Hopefully that will cure the groaning noises we are experiencing.
If this all goes as planned today, we are hoping to start running the new set of fatigue testing cycles through the night again; much to Shane’s wife’s delight with his constant checking of the live feed webcam when he’s at home!