Laboratory Reproduction of In-Flight Failures of Radomes 1999-01-2388
A companion paper in this conference gave an overview of the Joint Radome Programme results (paper 2322). This paper reports on experiments that were able to reproduce some features of the failures to radomes that had occurred in-flight despite passing ground based tests.
The electric field environment reviewed in the programme suggested that for most lightning strikes a more realistic test was to use a destressed electrode and the slower high voltage waveform D, rather than a rod electrode and a faster waveform A. Moreover other recent work also reported at this conference by Drumm et al, suggested that segmented divertor strips require higher light up voltages for slower voltage gradient waveforms.
Therefore a series of tests with this revised test configuration have been conducted on some A320 radomes supplied by DGA Toulon France equipped with segmented strips that had experienced in-flight failures. Tests were carried out both at the CEAT facility in Toulouse, France and at the Doulton High Voltage facility at Tamworth in the UK.
Similar results were obtained at each. In general the radomes passed the test with the faster waveform A applied between the electrodes but often failed when the slower waveform D was applied. Often punctures occurred without light up of the strips but with the puncture at the strip tip. This was a feature of the in-flight failures and confirms that the strip requires higher voltage to light up in these conditions, this higher light up voltage requirement results in overstressing of the dielectric leading to puncture.