5.6 Airframe Inspection, Records, ADs, and Corrosion Decisions

Airframe Inspection: Evidence, Not Assumption

An airframe inspection is a structured search for airworthiness evidence. The Airframe ACS includes part 91 inspection requirements, part 43 records, airworthiness directives, life-limited parts, special inspections, approved data, corrosion, and checklist use. The written test may ask a narrow fact, but the maintenance habit is broader: inspect the aircraft and records as one system.

A physical inspection without records can miss required actions. Records without a real inspection can hide current defects. A proper inspection identifies the aircraft, reviews status, checks required documents and records, verifies time or cycle limits, evaluates AD compliance, reviews previous discrepancies, and inspects the aircraft according to the required checklist or program.

A practical airframe inspection sequence includes:

• Confirm aircraft identity, configuration, and inspection basis.
• Review maintenance records, AD status, life-limited parts, and special inspections.
• Use an appropriate checklist for the required inspection.
• Open access panels and clean areas as needed for a meaningful visual inspection.
• Inspect structure, controls, landing gear attachments, seats, restraints, systems, placards, and required equipment.
• Classify discrepancies and determine whether approved repair data or additional inspection is needed.
• Make accurate maintenance-record entries for inspection results and corrective actions.

Corrosion is a recurring airframe inspection topic because it can begin in hidden locations and reduce strength. Uniform surface corrosion, pitting, intergranular corrosion, exfoliation, filiform corrosion, galvanic corrosion, and stress-corrosion cracking do not carry the same risk. Location matters. Corrosion on a nonstructural bracket is not the same as corrosion in a spar cap, pressure bulkhead, landing gear fitting, or control attach point.

Corrosion control is not just polishing metal until it looks better. The technician must remove corrosion within limits, avoid removing too much base metal, restore protection, and decide whether the part remains serviceable. If damage exceeds published limits, repair or replacement must follow approved data. Hidden corrosion may require more access, borescope inspection, non-destructive testing, or disassembly.

Airworthiness directives require careful compliance checks. It is not enough to say an AD was probably done. The technician verifies applicability by aircraft, engine, propeller, appliance, serial number, configuration, and effective criteria. Then the record must show the method of compliance, recurring interval if any, and current status. A recurring AD that was complied with once may still be due again.

Risk management during inspection includes avoiding both under-maintenance and over-maintenance. Under-maintenance misses unsafe defects. Over-maintenance can introduce damage, disturb systems, or replace parts unnecessarily. The best answer usually follows the checklist, uses current instructions, documents findings, and treats uncertain airworthiness as unresolved until evidence supports a decision.

For the exam, think like a certificated mechanic preparing to defend the signoff. If you cannot identify the data, measure the defect, verify the record, or explain the inspection basis, the safe maintenance decision is to keep troubleshooting before return to service.