Some extra information concerning cleaning for inspection:
Cleaning before an inspection is only necessary if the present dirt and/or too thick applied corrosion inhibiting compound (CIC) makes the inspection difficulty or impossible. In AMM 59 and on the task cards you read in nearly all cases: “clean if necessary”. CIC is made transparent on purpose to make inspection possible without removing it. There are several reasons why you want to reduce the cleaning task to an absolute minimum. Too much use of water and cleaningsolvents has a negative influence on structure and systems. The more maintenance activities, the presence of persons and implementation of (cleaning) operations, the larger the chance on negative impact. After cleaning you must apply CIC again. That is a precise job where means of protection must be used. There is again a chance of damaging components, for example drainvalves in the lower lobe and heat insulation blankets. If applicable you must re-lubricate afterwards. Because that’s extra on top of the normal lubrication-cycle this task happens extra times. Beside aforesaid technical reasons there are also still economic reasons. Superfluous operations cost money and extend the groundtime. If you do inspections ask yourself the if it is always really necessary to clean. Take into account thereby the above called effects.