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Lightning and static charging tests were performed on one transport aircraft radome and one small aircraft nose radome at the NASA Icing Research Tunnel (IRT), Lewis Research Center, Cleveland, Ohio. The primary purpose of these tests was to evaluate the effects of rain and icing conditions on the lightning protection effectiveness of segmented-type diverters. A secondary purpose was to evaluate the effects of static electrical charges deposited by rain and ice particles. The tests were performed under Task 2.4 of the Joint Program on Improving Lightning and Static Protection of Radomes. Fifty-four lightning tests were performed on two radomes to evaluate the effect of icing, precipitation drop size, and temperature on the ability of segmented diverters to prevent puncture of a radome skin and attachment to the internal radar antenna. Five of the tests resulted in radome puncture under icing conditions. One of the punctures occurred under rain without radome icing.

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.

One of the major goals of the EC-supported research programme FULMEN was to obtain a deeper understanding of the interaction of lightning with airborne objects. The improved knowledge of lightning attachment and sweeping processes has helped to derive scientifically founded guidelines and methodologies for the zoning of aircraft and helicopters to support and amend current and proposed regulations on lightning protection in aviation. For this purpose all the information relevant for zoning was collected in a database and analysed extensively. Theoretical models that describe various phases of the attachment of lightning to aircraft were developed, refined and validated against model experiments. While the complexity of lightning attachment still prohibits a complete analytical assessment of the process as a whole, significant advances have been made within FULMEN to present a coherent view of the interaction of lightning with aircraft.

The Joint Radome Programme was formed in February 1993 to investigate and research the effects of lightning and static electricity on aircraft radomes and dielectric fairings. Some preliminary results were presented at the Williamsberg Conference in 1995. Since then experiments have been completed that have recreated in the laboratory some of the features of in-flight failures; these have included both radome measles and punctures of radomes that had previously passed existing test methods. This paper gives an overview of some of the key results and the implications on test techniques.