Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above that would supersede an existing AD. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
The TC Holder received from operators, whose fleets are operated in demanding operating-conditions and with very frequent Short Take- Off and Landing (STOL) operations, reports of cracks located in the web of fuselage frame 19. On 05 February 2007, EASA issued Airworthiness Directive (AD) 2007-0028 which mandated Alert Service Bulletin (ASB) 228-266 and required an inspection of the frame 19 on all Dornier 228 aeroplanes. In addition, the TC Holder also initiated a flight-test campaign including strain measurements as well as finite element modelling and fatigue analyses to better understand the stress distribution onto the frame 19 and the associated structural components.
The results of these investigations confirmed that STOL operations diminish extensively the fatigue life of the frame 19.
Fuselage frame 19 supports the rear attachment of the Main Landing Gear (MLG). This condition, if not corrected, could cause rupture of frame 19, leading to subsequent collapse of a MLG.
The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.