The regulations do not consider physical cleaning of an aircraft as maintenance or preventative maintenance.  However, when preparing the aircraft for cleaning requires removal of components or protection of components, that may fall under the definition of maintenance or preventative maintenance.  For example, before cleaning an aircraft, it may be necessary to close and secure the upper and lower fan cowl doors on a transport category aircraft.  The FAA considers the closing and securing of the engine fan cowl doors maintenance.  Additionally, after the cleaning process, it may be necessary to reapply lubrication compounds and preservatives to aircraft components, both of which could be considered maintenance/preventative maintenance.  Conversely, we do not consider cleaning seat cushions/covers maintenance or preventative maintenance.