When I was at Goose Bay Labrador in 1966 we had an H model (65-976) that went into a flat wing spin,they were doing power on stalls,at 10k and recovered it at 2500 ft,the w/w doors had popped out in to the air stream and were ripped to the top of the w/w,.Lockheed sent a team to look at it,the "G" meter was pegged in both directions.They told us to fix it and fly it.From then on it required 2 1/2 degrees left trim to fly straight and level.