This NES specifies the design requirements for Maintenance Envelopes and Removal for all marine engineering equipments installed in HM Surface Ships. It is primarily to aid the Equipment Designer, Design Authority and Shipbuilder and defines the method of establishing the space required for operation, maintenance and removal of equipments. The broader aspects of space requirements are included in Sea Systems Controllerate Publication No 40( I) Management of Design for Upkeep and Support of Non-Weapon Systems and Equipment (MANDUS).

Removal information for items external to the hull (propellers, stabilizer fins, etc) is not included in this NES. Such information will be given in the equipment publication concerned where preparation for removal and removal procedure cannot be sensibly divided.

The space required for the maintenance and removal of equipment is an essential feature of Surface Ship design. A number of factors need to be considered, some of which may be outside the scope of this standard. These instructions are however to be followed unless overridden by the Design Authority and with the approval of the appropriate Ship Project Officer.

Requirements specified in this NES are to be applied during As & As and subsequent refits.