US FAR 23.221 covers the spin requirements for normal category aircraft ( ie not approved for spins)Sec. 23.221 — Spinning.(a) Normal category airplanes. A single-engine, normal category airplane must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery, or demonstrate compliance with the optional spin resistant requirements of this section.
My understanding is the above instructions are compliance for certification. It does not mean an aircraft is approved for spinning.
For example, the Cessna 172 Model 172N Skyhawk Information Manual published by the manufacturer I July 1979, states the following in the chapter on Limitations under the heading
MANEUVER LIMITS - Normal Category.
This airplane is certificated in both normal and utility category. The normal category is applicable to aircraft intended for non-aerobatic operations.
These include any maneuvers incidental to normal flying, stalls (except whip stalls), lazy eights, chandelles, and turns in which the angle of bank is not more than 60 degrees. Aerobatic maneuvers, including spins, are not approved