OEMs don't write FMs to facilitate the end user's day to day operations they are written as a legal statement of how they believe the helicopter should be operated given all the knowledge in their domain - which may be more than the knowledge in the public domain. Should you chose to operate in another way then that is at your risk not then at their risk. If you chose not to get some kind of approval* or 'no objection' statement then you risk having to stand up in court and justify why your version of a protocol is more valid than the one created by the bloke that designed and built it. Not a task I would relish.
I am the last person to agree that OEMs get everything right for any emergency checklist that omits the three vital components:.........
Immediate Actions ........
Subsequent Actions .......
Considerations .........
cannot be considered to be complete. But then again the OEM's Emergency Procedures lack a context which is best provided by the operator. He is the only one intimately acquainted with his fleet configuration, his operating area and the type of work undertaken. It's only ignorance, laziness and/or lack of resources that leads people to live with the OEM's QRH when it could be improved upon considerably if they had the time, the money and the inclination.
Onwards and upwards
G.
* If the company includes its revised checklists in it's OM which is then reviewed as part of the AOC/CAT process and it comes through unscathed then the chances are you have dotted that particular 'i'. I think this is what in effect occurs in JARland whether we realise it or not.