Originally Posted by
chips_with_everything
The limits need to be based on the engine, not the airspace. Data from the manufacturer please. Not recommendations, firm and clear limits.
GE, for one, has transmitted advice to its operators as of 21 April specifying ash concentrations where operation may be conducted as routine, requires additional maintenance, requires yet more maintenance, and is not recommended.
I believe they cannot provide limits, because limits are a regulatory matter and cannot be imposed by an OEM, whether they wish to or not; if you look at any OEM document, any page with a Limitation is invariably marked as being Approved by a regulatory authority.
If OEMs could impose Limits on their own it'd be a license to print money.