The FAA today published a Notice of issuance of advisory circular for Advisory Circular (AC) 23-21, Airworthiness Compliance Checklists Used to Substantiate Major Alterations for Small Airplanes. The AC provides guidance material for the creation and use of airworthiness compliance checklists that can be used by Airframe and Powerplant (A&P) mechanics with Inspection Authorization (IA) and by Federal Aviation Administration (FAA) Airworthiness Safety Inspectors (ASIs) when making/approving major alterations to small airplanes.
This AC is limited to “major” alterations, as defined in 14 CFR, part 1, as opposed to complex alterations that require a Supplemental Type Certificate (STC), per FAA Order 8300.10. The AC is neither mandatory nor regulatory and does not change any previously released FAA guidance material. Rather, the AC is intended to “provide a tool to work within existing approval processes” and is specifically meant to be used in conjunction with and to complement AC 43-210, Standardized Procedures for Requesting Field Approval of Data, Major Alterations, and Repairs. The FAA notes that “the use of these checklists during the return to service of a major alteration is not mandatory nor does it alter any previously acceptable method.”
Although the draft advisory circular was issued for Public Comment on May 28, 2004, the FAA did not receive any comments to the draft advisory circular.