Initially, the Minimum Equipment List (MEL) is a document that lists equipment that may be temporarily inoperative at the commencement of the flight. (An inoperative item means that the item does not accomplish its intended purpose or is not consistently functioning within its approved operating limits or tolerances).

This document is produced by the Operator for their own particular aircraft taking into account of the:

• Aircraft configuration

• Operating environment;

• Route;

• Structure;

• Geographic location and

• Maintenance capabilities.

The MEL is approved by the Competent Authority.

In addition, MEL is based on the Master Minimum Equipment List (MMEL) which is a document approved by the Agency and establishes the aircraft equipment allowed to be inoperative under conditions specified for a specific type of aircraft.

The MMEL is produced by the aircraft manufacturer.

Furthermore, regarding the EASA regulations, they serve the purpose of safeguarding aviation safety, fostering harmonization and efficiency, supporting industry growth, and promoting environmental sustainability within the European aviation sector.

The Operations Manual provides detailed procedures and instructions specific to the particular helicopter model and its equipment. It typically includes information on emergency procedures, abnormal situations, and equipment failures in the section with the heading "Emergency Procedures".

It outlines step-by-step actions to be taken in case of various failures, including those occurring during taxi. It may also include checklists, troubleshooting guides, and specific limitations or considerations for taxi operations.

Therefore, it is obvious that Operations Manual under the heading "Emergency Procedures" will be the primary reference document.