Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Fokker Model F27 Mark 200, 400, 500, and 600 airplanes. This proposed AD would require a general visual inspection of the rotary knobs for the fuel tank isolation valves to determine if the seal wire has been installed correctly and corrective actions if necessary. This proposed AD is prompted by investigation of a recent accident, which found that the rotary knobs controlling the fuel tank isolating valves had been in the shut position. We are proposing this AD to ensure that the rotary knobs are not inadvertently moved to the shut position, which could result in fuel starvation to both engines and consequent inability to maintain controlled flight and landing.