Chapter 7: Aircraft Maintenance 7 7-3 experimental Aircraft FAA resources Preflight Inspection Transponder Inspection Altimeter System Inspection minimum equipment list/Configuration  deviation list repairs and Alterations Progressive Inspection All repairs and alterations of standard airworthiness  certificated aircraft are classified as either major  or minor. 14 CFR part 43, appendix A, describes the alterations and repairs considered major. Major  repairs or alterations are approved for return to  service on FAA Form 337, Major Repair and Altera- tion, by an appropriately rated certificated repair  station, an FAA-certificated A&P mechanic holding  an IA, or a representative of the Administrator.  Minor repairs and minor alterations may be  approved for return to service with a proper entry  in the maintenance records by a certificated A&P  mechanic or an appropriately certificated repair  station.  Alterations to light-sport aircraft certificated in  the light-sport aircraft category under 14 CFR  part 21, section 21.190, must be authorized by the  manufacturer or a person acceptable to the FAA in  accordance with 14 CFR part 91, section 91.327.  To minimize maintenance downtime, the owner may  opt for a progressive inspection plan. Progressive  inspections benefit owners whose aircraft experience  high usage such as fixed base operators (FBOs), flight  schools, and corporate flight departments. Unlike  an annual inspection, a progressive inspection allows  for more frequent but shorter inspection phases, only if all items required for the annual and 100-hour  inspections are inspected within the required time.  The authority to use a progressive inspection plan is non-transferable. Once the aircraft is sold, an annual becomes due within 12 calendar months of  the last complete cycle. The 100-hour inspection  is due at the completion of the next 100 hours of  operation. Most airframe manufacturers provide a boilerplate progressive maintenance plan. 14 CFR Part 43, Appendix D, Scope and Detail of  Items (as Applicable to the Particular Aircraft) To  Be Included in Annual and 100-Hour Inspections,  contains a list of general items to be checked during  inspections. The aircraft’s static system, altimeter, and automatic altitude-reporting (Mode C) system must have been inspected and tested in the preceding 24 calendar months before flying instrument flight rules (IFR) in  controlled airspace. 14 CFR Part 43, Appendix E,  Altimeter System Test and Inspection, lists the items  that must be checked. If your aircraft has an approved Minimum Equipment  List (MEL), the MEL should be used to determine if a flight may be initiated with inoperative aircraft  equipment without the issuance of a special flight  permit. Your Airplane Flight Manual (AFM) may also  include a Configuration Deviation List (CDL) pre- pared by the manufacturer. The transponder must be inspected every 24 calen- dar months. 14 CFR Part 43, Appendix F, ATC  Transponder Tests and Inspections, lists the items  that must be checked. Additionally, the installation of  or modification to a transponder must be inspected  for data errors as well. A pilot is required to conduct a thorough preflight  inspection before every flight to ensure that the  aircraft is safe for flight. Pilots should review the  maintenance status of the aircraft as a part of the  preflight inspection. If your aircraft does not have an approved MEL, and  you have inoperative equipment or instruments,  then you must refer to 14 CFR part 91, section 91.213,  to determine if a special flight permit is needed to  operate the aircraft. You can find all of the maintenance requirements  applicable to your aircraft in 14 CFR by accessing the relevant regulations on the FAA website at www.faa.gov. The best resource for answering  questions about the maintenance necessary on your aircraft is your local FSDO. If you make any major alterations to your  experimental aircraft, you must notify your local  FSDO of those alterations. 