flying F27s, periodically we would have to weigh the load when fuel was really critical and we were after every last drop.
Yes, when I was flying home from Maseru, Lesotho decades back, I had a ticket, though was not told which day, as pax were boarded in the order they bought tickets, as the payload of the day would permit. The density altitude and winds were factored into the aircraft performance of the day, and the appropriate weight of pax boarded, in the order they bought their tickets. Inconvenient, but I have no way to criticize doing it right!
The investigator gave me a call to let me know that the aircraft had disintegrated around my restraint system
I had a similar situation with a highly modified Cessna 207 I configured and approved in 2005. The pilot eventually bunged it up, and crashed. The plane burned completely. I had the unpleasant, though necessary duty of discussion with the coroner exactly what killed the pilot. Though sadly, happily for me, the 700 pounds of equipment I installed and restrained right behind the two front seats did not hit the pilot from behind, but rather he succumbed to fire. Many of my approvals are for restrained loads in cabins, and I like to aim for much greater capacity than the 9G crash load requirement which is common to many older aircraft's certification basis.
In this photo of AWI's "Polar 5", a Basler Turbine DC-3 which I approve;
The "father" of AWI's advanced radar systems, Dr. Heinz Miller, stands near the rack installations I approve with each new configuration, which include the diagonal restraint cables to the ceiling I insist on (covered in marker tape). I have load tested the racks, and they meet the crash loads without the cables, but I sleep at night, knowing that the cables are there too.
I reluctantly accept that we cannot regulate heavy weight people to not use airplane seats. However, somewhere there must be a balance of safety for those occupants who otherwise fall within the design assumptions for airplanes. It has been the case that entire multi seat assemblies have been torn off the the aircraft structure with the occupants still strapped in. In the case of a crowded aircraft cabin, this could affect other occupants, particularly around emergency exits. I complained once about a Canadian flight in which I was seated in an exit row, and the occupancy of the seat row across from me obviously exceeded the design capacity of the seat assembly. I could never have approved that combination. Transport Canada told me it was a political hot potato, which they would not take on. On the flight to Vancouver I rode yesterday, sure enough, two occupants of an exit row seat row, would have appeared to exceed the 170 pound per person assumption by at least double. I do respect Southwest Airlines, who have found a politically correct approach to limiting misoccupancy: Every exit seat row is placarded: "the use of seatbelt extensions in this row is prohibited". Forward thinking - one day, there will be an accident in which overweight occupants dislodge during a crash, and obstruct an exit path, and then this will be revisited. In the mean time, the new much higher dynamic seat load requirement helps...