It is confusing, but I think I understand what Herb is saying.
The AD covers two items: Spars CAPS and spar WEBS.
P-models are only affected by the spar CAP AD up to serial P3370138 - this would include all the P337G models.
The P337H models are exempt by serial number.
The spar WEB portion of the AD applies to all P-model UP TO P3370313. After that serial, they are exempt. So some P337H airframes are 100% exempt from this AD, while other are only affected only by the WEB inspection. Covered P-model S/Ns must have 10000 hours TTAF before the AD becomes effective, then re-inspect every 500 hours.
Is this clear as mud?
