When am I required to weigh my business aircraft?

I get this question a lot. When am I required to weigh my aircraft?

As you might expect, like so many issues surrounding aircraft, there are a multitude of correct answers depending on the circumstances. Here are a few examples: 

• When operating under FAR 135, an aircraft must be weighed every 36 calendar months to establish its current empty weight and center of gravity. If the aircraft was issued an original airworthiness certificate within the last 36 calendar months and is operating under a weight and balance system approved in the ops spec of the certificate holder, the aircraft is exempt from this requirement.
• Many OEMs do not have weighing requirements post-paint, however; they do consider how much paint was removed during the process: sanded vs. stripped vs. new. Additionally, when composites are lightly sanded, filler primed and then painted, you are not taking them down to the bare fibers, but actually adding to the previous coatings. All that being said, many feel it is prudent to weigh your aircraft after paint. 

Aircraft modifications such as updating the flight deck to cabin configurations can change your aircraft's weight by several hundred pounds. Although many times these weights are calculated, it is not unheard of to experience a favorable weight advantage when the aircraft is weighed vs. what has been calculated.