For nearly a century, ice build-up on aircraft surfaces has presented a safety concern for the aviation industry. Pilot observations of visible moisture and temperature has been used a primary means to detect conditions conducive to ice accretion on aircraft critical surfaces. To help relieve flight crew workload and improve aircraft safety, various ice detection systems have been developed. Some ice detection systems have been successfully certified as the primary means of detecting ice, negating the need for the flight crew to actively monitor for icing conditions. To achieve certification as a Primary ice detection system requires detailed substantiation of ice detector performance over the full range of icing conditions and aircraft flight conditions. Some notable events in the aviation industry have highlighted certain areas of the icing envelope that require special attention.
Following the CRJ accident in Fredericton, New Brunswick, Canada, in December 1997, industry interest and scrutiny in the performance of ice detection systems at warmer temperatures has increased. [
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] In particular, the concern lies in potential differences between ice accretion on the ice detector sensing surfaces and the critical aircraft surfaces (e.g. wing, nacelle). This has led both the FAA and EASA to update advisory material to ensure that ice detector performance at low freezing fractions is addressed.
To minimize this concern and alleviate the risk, Collins Aerospace (Rosemount Aerospace, Inc.) has developed an enhanced ice detection algorithm for its magnetostrictive ice detector (MID). Traditionally the MID has only been used to detect ice accretion resulting from supercooled liquid water. This new algorithm enables the MID to sense the presence of non-freezing liquid water on its sensing surface and couple that with ambient temperature information to provide a signal when conditions may be conducive for ice accretion on critical aircraft surfaces.
The discussion in this paper describes the development of this new algorithm for the MID and performance verification of the algorithm through icing wind tunnel testing and icing flight tests.