Monitoring Aircraft Microclimate and Corrosion

CSIRO, Boeing, DSTG and the RAAF have undertaken a number of monitoring programs of microclimate and corrosion within different internal spaces in a number of aircraft. Past programs have looked at conditions within an RAAF-707 (sub-floor area) and an Air New Zealand 747 (sub-galley). The current program looks at a number of spaces in two RAAF C-130s based at Richmond, NSW. The spaces include Empennage, Cargo door and above LH Main Wheel Well. Monitoring of the C130s is now in its second year of engagement. The data derived in each monitoring program includes the ambient air relative humidity, surface relative humidity, ambient air temperature, surface air temperature, surface wetness and corrosion as measured by a corrosion sensor. This data allows relationships between microclimate, wetness and corrosion to be established as well as relationships between base location, flight patterns, position in aircraft and microclimate to be derived. It is observed that in some cases wetness and corrosion are directly related to microclimate and are associated with such phenomena as condensation or "rain in plane". In other cases there is no apparent microclimatic cause for wetness or corrosion events. The relevance of the data to the corrosivity of different aircraft spaces, base locations and flight patterns is reviewed and implications for maintenance are assessed using the current data from the C130s. Work is progressing on deriving generic software for predicting aircraft internal microclimate from flight path, time of day and month of year using this data.