Federal Aviation Administration June 18, 2010 – Federal Register Recent Federal Regulation Documents

We propose to adopt a new airworthiness directive (AD) for certain Model DC-9-81 (MD-81), DC-9-82 (MD-82), DC-9-83 (MD-83), DC-9- 87 (MD-87), and MD-88 airplanes. This proposed AD would require installing fuel level float and pressure switch in-line fuses on the wing forward spars and forward and aft auxiliary fuel tanks, depending on the airplane configuration. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

We propose to adopt a new airworthiness directive (AD) for the products listed above. 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: Two cases of a crack on a ``dry'' ADG [air driven generator] (Hamilton Sundstrand part number in the 761339 series), in the aft area of the strut and generator housing assembly, have been reported on CL-600-2B19 aircraft. The same part is also installed on CL-600-2C10, -2D15 and -2D24 aircraft. Investigation determined that the crack was in an area of the strut where the wall thickness of the casting was below specification, due to a manufacturing anomaly in a specific batch of ADGs. Structural failure and departure of the ADG during deployment could possibly result in damage to the aircraft structure. If deployment was activated by a dual engine shutdown, ADG structural failure would also result in loss of hydraulics for the flight controls. The proposed AD would require actions that are