EASA SIB AIR750-2026-06-S-5700-ACS — Lower Wing Skin Cracking

Summary

The Lower Wing Skin Cracking Airworthiness Concern Sheet issued by the Federal Aviation Administration (FAA) addresses reports of cracks in the lower wing skin cutouts near the main landing gear truss on Twin Commander aircraft models 500 series through 720. The document highlights Maintenance Alert MA23001 issued by Twin Commander Aircraft LLC, recommending recurring inspections to detect these cracks. It also references a related Australian Civil Aviation Safety Authority Airworthiness Directive AD/AC/92 for similar inspections on affected aircraft.

What Changed

This document introduces a coordinated airworthiness concern regarding lower wing skin cracking on multiple Twin Commander aircraft models, recommending recurring visual and non-destructive inspections. It requests information from operators and maintenance personnel to evaluate the extent of the issue and determine if further regulatory action, such as an Airworthiness Directive, is necessary.

Why It Matters

This concern is critical for aviation professionals because undetected cracks in the lower wing skin can reduce wing residual strength, potentially compromising flight safety. Operators, maintenance organizations, and compliance teams must be vigilant in inspecting these areas to prevent structural failures and ensure continued airworthiness of affected Twin Commander aircraft.

What To Do

Operators of affected Twin Commander models should perform inspections of the lower wing skin cutouts near the main landing gear truss within six months and annually thereafter, following Maintenance Alert MA23001. They are encouraged to report findings, including crack details and inspection methods, to the FAA to assist in the evaluation of this airworthiness concern. No formal compliance deadline is mandated yet, but timely action is recommended.