Development and evaluation of a water removal technique for the CF188 rudder.

摘要

The Flight Control Surfaces (FCS) on the CF188 Hornet fighter aircraft are susceptible to water ingress into the aluminum honeycomb core, which causes structural degradation. The rudder is the most commonly affected component and several rudders have departed the aircraft during flight. Of the several non-destructive testing (NDT) methods, which can detect water within the FCS, neutron imaging is considered the most sensitive and is available at the Royal Military College (RMC) of Canada.;With such an ability to locate the water in each honeycomb cell, the next task is to develop a non-invasive and reliable water removal technique. Using both complete rudder and coupons made from one, the variables of temperature, time, vacuum and path were investigated. It was found that optimal drying conditions included a temperature of 90°C and a maximum allowable vacuum pressure of approximately 16.7 kPa (25 "Hg).;Water egress paths used during drying cycles were evaluated using neutron radioscopy. A new system was installed at RMC for this research and provided near real-time images of the drying process. Through the examination of degraded adhesive bonds, it appears that water travels primarily through the degraded filet bonds.;With a view to having a field capable technique, a dew point meter was included. The level of dryness observed on neutron images was correlated to the data obtained from the meter. This correlation revealed that when the dew point meter reading dropped below 10% relative humidity for over one hour, the rudder could be considered dry.