Question for an N reg paperwork expert
 

I am updating my logbooks to record changing my bog standard 8:00x6 tyres for the Alaskan Bushwheels . From reading on the net what self maintenance an owner is allowed to do, tire changing is amongst the list to be followed by a logbook entry of work done and accompanied with my FAA PPL number and signature , also the Tundra tires have their own FAA STC included in which it specifically allows me, a non A&P, to install them.

The issue I have is with the official Weight + Balance in the AFM, I notice there are several sheets regarding W+B one is the actual document when the aircraft was weighed at the factory and signed by an A&P, the second is an amended weight and balance (when the avionics were changed) this "weight amendment form" was signed by the avionics shop.

My questions is taking into account that I am allowed to change tires under the FAA self maintenance list, I am also allowed to install the heavier Tundra tires under the STC, Am I also allowed (in addition to the appropriate logbook entries) to insert and sign an amended weight and balance into the AFM to reflect the weight differential between the old and new tires (26lbs)? . I see nothing in FAA documents allowing a PPL the authority to amend the official AFM weight and balance docs.

I'm no expert but...
 

When you fit an STC, you need to fill out a 337 form and submit it to the local FAA office. You need to effect the steps taken in fitting on the reverse of the form, state how the W+B has been updated and insert any instructions for continuos airworthiness into the relevant manuals.

What size BWs did you go for? Did you do the TW too?

Irish

26 in, did not do the TW

N3110J - Private Maule MX-7 series Super Rocket at Perth - Scone | Photo ID 248353 | Airplane-Pictures.net

I always thought an STC was like a pre approved modification whereas a 337 was a field change that required individual field approval fro the FAA.

I will pull back out the paperwork and reread it

If you're using a STC I think you need to put in the 337 so that the americans have on their record the changes, Just incase you are to lose the logbooks , etc. I think that with an STC you need it signed off by an A&P and possibly IA . I had a similar sort of thing with my bushwheels, although mine were valid under the type certificate rather than STC

The STC is the FAA's approval to the supplier of the modification that their product is OK for use on whatever the STC specifies. It's usually not specific to an aircraft serial number. The Form 337 is serial number specific, and must be submitted to the FAA so that their records reflect reality.