Sport Pilot Certificate Upgrade to Private, related to Knowledge Test
This is a specific question:
I have already passed the Private Pilot Knowledge Test.  
Have training hours toward PP certificate. 
If I complete the training for and get a Sport Certificate prior to the PP Knowledge Test expiring and I then want to do the additional training for PP certificate and it's passed the original expiration date of the PP Knowledge Test, 
will I have to do any more testing related to Knowledge in order to complete training for and get the PP Certificate. 
I understand that there would be an additional checkride involved. 

3 Replies
Yes, if you do not take and pass the PP practical test before the PP written test expires, you will have to take and pass the PP written again before taking the PP practical.  Also, you will have to take and pass the Sport Pilot written before taking the Sport Pilot practical test; the PP written does not fill the written square for Sport.  The main reason for that is the Sport Pilot written covers the privileges and limitations of a Sport Pilot while the PP written does not.  While there is a shorter transition written for Recreational Pilots upgrading to Private, there is no similar transition written to upgrade from Sport to Private.
It's great to get a quick, direct answer. This will help in making a decision. 
Hi, Thomas!

Ron, once again, is right; you'll need an unexpired written test for each check ride.

Since you can train in and even take your Private check ride in a Light Sport Aircraft, your biggest question is probably how much PP-qualified training you have now.  Any SP instruction "magically" becomes valid toward your PP requirements once you have your Sport Certificate, so since most folks take many more than just the minimum hours to get to SP or PP you can take advantage of learning at a lower cost and only having to "bolt on" night experience for the second check ride.  If you are already comfortable as a pilot and close to your check ride, and if you have most or all of the minimum hours under your belt, then going straight to Private is probably more cost effective.

Good luck in your journey! :-)
David T-G
Sport Instructor - Airplane