I see it all over the place though.

"6) Aircraft occupancy is limited by the engine's Sea Level Horsepower
rating. There will be a minimum of 60
horsepower per occupant, unless a specific waiver - by mission/sortie
-- is granted by the wing commander for
aircraft with proven performance with less than 60 HP per occupant For
example, a 230 HP Skylane and a 180 HP
Skyhawk shall both be limited to a maximum of three occupants. However,
the wing commander may waive flight
operations in an airplane such as a Citabria or Piper Super Cub with
more than one occupant per 60 HP."

https://ntc.cap.af.mil/ops/dov/Suppl..._1/pacrsup.pdf