A Mechanic assigned to perform an ETOPS check and walk around on a B777 with heavy snow accumulation; requests the aircraft be de-iced; to avoid an incomplete visual inspection. His carrier does not have a written policy on de-icing aircraft prior to ETOPS inspections.

Narrative

I was assigned the ETOPS check on aircraft X; it was snowing and the aircraft had heavy snow accumulation on it; hindering the visual inspection. I asked for the aircraft to be de-iced; so I could complete the inspection. A discussion followed with management. The Supervisor referred to the de-icing as a 'courtesy.' I have encountered this mentality in every ETOPS inspection during snowstorms. It will continue until the air carrier establishes a written policy on de-icing aircraft prior to ETOPS inspections. As far as I know; my aircraft was the only one de-iced to facilitate the walk around inspection. Air carrier needs engineering bulletins and a procedure manual reference to automatically de-ice airplanes for ETOPS inspections; or else an incomplete visual inspection may occur.Callback conversation with reporter revealed the following information: Reporter stated he was told; there was enough of the wings and fuselage visible for him to accomplish the ETOPS walk around inspection and sign off the check. Reporter stated his carrier does not seem to have any intention of developing written procedures; to address when de-icing should be used to properly complete an ETOPS inspection for maintenance personnel.