That has been a common question up in Alaska since many pilots switch gear from wheels to skis to floats and back to wheels before the next annual.
FAA FAR 91.403 General.
(a) The owner or operator of an aircraft is primarily responsible for maintaining that aircraft in an airworthy condition, including compliance with part 39 of this chapter.
Link to most current FAA FAR PART 91 regulations:https://www.ecfr.gov/cgi-bin/text-idx?SID=994370bf6bfe45247fb4092ac214af70&mc=true&node=pt14.2.91&rgn=div5
Another way to understand what that means;
If you have any questions about anything you haven't experienced before bring in someone who has the experience and knowledge. A Boeing 737 mechanic with no General Aviation experience my hold the certificate but use common sense. A homebuilder or owner with no A&P but lots of experience and knowledge is a better choice for answering questions. Regulations still say an A&P or Repairman will do "Inspections". The aircraft does not need an inspection after switching gear if the gear has been on before. Weight and Balance is always required on any change to aircraft that effects the Center of Gravity or Empty Weight.
Quite often I use the owners knowledge to sign-off gear changes because they have more experience then I do with the installation. The mechanics involvement then just turns into a regulation and paperwork procedure. Sometimes I get called in just to give the owner confidence and another set of eyes because, who is the final responsible person for the aircraft's safety?
Klaus Marx - Piper Pacer Pilot
Juneau, AK & Wenatchee, WA . . . . . . Click on Link Bar to view the 'non-profit' group.