The FAA issued a Special Airworthiness Information Bulletin (SAIB) for certain models of the Beechcraft King Air F90, 200, B200, 300, B300 and Commuter 1900 series (specific models on type certificate data sheet A24CE) due to the potential for corrosion in the empennage structure. This airworthiness concern is not an unsafe condition that would warrant Airworthiness Directive action, the FAA has determined.
The SAIB stems from the FAA's Wichita Aircraft Certification Office receiving reports from the Beechcraft Repair Design Office (RDO) of approximately 100 repairs in the past decade to address structural corrosion of the empennage. Typically, the RDO is consulted when corrosion levels exceed repair limits governed by the standard repair manual (SRM). Beechcraft reported that the most extreme corrosion was experienced on the rear spar cap (or chord) of both the horizontal and vertical stabilizers. However, corrosion damage was not limited to those areas and was also discovered inside the horizontal and vertical stabilizers.
Although the horizontal and vertical stabilizers were originally designed with access panels, Beechcraft has designed kits for the installation of additional access panels to facilitate more thorough inspections of these areas. Beechcraft has also revised the airworthiness limitations manual (ALM) of the instructions for continuing airworthiness for the affected models. The respective ALMs refer to inspections defined in the SRM for each model.
The FAA recommends that the latest revision of the airworthiness limitations be incorporated for affected airplanes to ensure corrosion inspections for both the horizontal and vertical stabilizers are included in the maintenance program.