The info on the definition of changing weight and balance is particularly interesting. You might need to do a new W&B check after an alteration without having affected weight and balance limits, and therefore not having made a major alternation by that definition.
This US AOPA article highlights a common practice where A&Ps write out a 337 for just about everything and it gives everybody a warm feeling. It’s usually going to be completely wrong, not least because a 337 has to be backed by an STC or Field Approval related documents.
