Originally Posted by
treadigraph
Now that Dave has stirred the mud a little, I always thought it odd that the Aztec shares the PA-23 designation with the Apache (certification purposes?) but has c/ns prefixed "27-" which I think was the Piper project number?
Yes, the Apache and Aztec share the same Type Certificate (1A10). The TC differentiates between the 150/160 hp O-320 powered Apaches (with 23- MSNs) and the 235/250 hp O-540 powered Apaches/Aztecs (with 27- MSNs).