Reporter alleges proper Repair Station maintenance and recording procedures were not followed for work on a Eurocopter AS-350 aircraft.

Narrative

A Mechanic under the direction of the Director of Maintenance (DOM); cut a 2' x 4' hole in a structural bulkhead to allow the passage of video cables from the left cargo area into the cabin of a Eurocopter AS-350. This issue had been discussed previously with local FAA and there would be no approval (from FAA); unless there was a Designated Engineering Representative (DER)/ Manufacturer Engineering; to provide approved technical data for this hole. The DOM had been informed; that a DER had been out (visiting) and reviewed the proposed action but no FAA 8110-3 had been finalized. The DOM proceeded to contact a Eurocopter Technical Representative (Rep) for approval. The Technical Representative's reply was to use ' proper Sheet Metal (SM) practices and reinforcements '. There was no engineering data provided. There was no log entry completed; no FAA 337 submitted (to substantiate the work) and the installation of the hole and SM doubler does not meet the requirements of Advisory Circular AC. 43.13-1b Chapter 4. The aircraft is operated under Part 135 and maintained by the Part 145 Repair Station.Disregard for following proper repair station procedures and not recording maintenance in accordance with FAR Part 43.9 are factors.