Airworthiness Directives; Learjet Model 45 Airplanes
The FAA is revising an earlier proposed airworthiness directive (AD) for certain Learjet Model 45 airplanes. The original NPRM would have required revising the Airworthiness Limitations section of the airplane maintenance manual to incorporate certain inspections and compliance times to detect fatigue cracking of certain principal structural elements (PSEs). The original NPRM resulted from new and more restrictive life limits and inspection intervals for certain PSEs. This action revises the original NPRM by changing the applicability to add certain airplanes. We are proposing this supplemental NPRM to ensure that fatigue cracking of various PSEs is detected and corrected; such fatigue cracking could adversely affect the structural integrity of these airplanes.
Airworthiness Directives; Boeing Model 777 Airplanes
The FAA is revising an earlier proposed airworthiness directive (AD) for all Boeing Model 777-200, -300, and -300ER series airplanes. The original NPRM would have required, for the drive mechanism of the horizontal stabilizer, repetitive detailed inspections for discrepancies; repetitive lubrication of the ballnut and ballscrew; repetitive measurements of the freeplay between the ballnut and the ballscrew; and corrective action if necessary. The original NPRM resulted from a report of extensive corrosion of a ballscrew in the drive mechanism of the horizontal stabilizer on a Boeing Model 757 airplane, which is similar in design to the ballscrew on Model 777 airplanes. This action revises the original NPRM by adding airplanes to the applicability. We are proposing this supplemental NPRM to prevent an undetected failure of the primary load path for the ballscrew in the horizontal stabilizer and subsequent wear and failure of the secondary load path, which could lead to loss of control of the horizontal stabilizer and consequent loss of control of the airplane.
Airworthiness Directives; Airbus Model A300-600R Series Airplanes; and Model A310-300 Series Airplanes
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: