A note on spin certification.
All smaller fixed wing aeroplanes are spun during certification. Broadly speaking there are two levels of rigour to which this is done. One is a non-aerobatic certification programme, such as for example would have been done on the PA28; this is there to answer three questions, which are...
- Will it spin
- How does it spin
- Does it recover, and how
Any non-aerobatic aircraft with an excessive tendency to spin, or a severe reluctance to recover won't get certified. Some have suffered such problems but had them solved and a mod made to the aircraft before approval.
For an aerobatic or deliberate spinning clearance, a LOT more spinning is needed, included multiple turns, mishandled entries, mishandled recoveries, failure to close the throttle, etc, etc.
Manufacturers may go for a non-spinning clearance for one of two reasons. One is that they simply don't want to bear the cost of a full spinning test programme. The other is that the aircraft can pass the standard non-aerobatic criteria but has other characteristics (such as a tendency to wind-up, or perhaps enter a flat spin after a certain number of turns) which would make routine deliberate spinning severely inadvisable.
Only problem is, unless you were on the certification team, you don't know which is the reason!
G