Federal Aviation Administration November 9, 2010 – Federal Register Recent Federal Regulation Documents

We propose to adopt a new airworthiness directive (AD) for certain Model 750 airplanes. This proposed AD would require an inspection to determine the serial numbers of the auxiliary power unit (APU) generator and the left and right engine direct current (DC) generators, and related corrective actions if necessary. This proposed AD would also require revising the airplane flight manual. This proposed AD results from a report of a DC generator overvoltage event which caused smoke in the cockpit and damage to numerous avionics and electrical components. We are proposing this AD to detect and correct an overvoltage condition on the DC electrical busses caused by exciter stator winding failures, and subsequent failure of the generator control unit (GCU) overvoltage protection circuitry, which could result in damage to critical electrical and avionics components.

We are adopting a new airworthiness directive (AD) for the products listed above. This 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:

We are adopting a new airworthiness directive (AD) for the products listed above. This 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:

We are adopting a new airworthiness directive (AD) for the products listed above. This 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:

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires repetitive high frequency eddy current inspections to detect cracking in the vertical radius (also known as the ``vertical leg'') of the upper cap of the center wing rear spar, and repair if necessary. This new AD expands the area to be inspected by including inspections to detect cracking of the horizontal flange of the upper cap of the left and right center wing rear spar, and repair if necessary. This new AD also adds certain airplanes to the applicability. This AD was prompted by reports of cracking in the vertical radius of the upper cap of the center wing rear spar, and the horizontal flange on the inboard side of the of the rear spar upper cap, which resulted from stress corrosion. We are issuing this AD to detect and correct cracking in the vertical leg or the horizontal flange of the upper cap of the left or right center wing rear spar, which could cause a possible fuel leak, damage to the wing skin, and structural failure of the upper cap, and result in reduced structural integrity of the airplane.