Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Aerospatiale Model ATR72 airplanes. This proposed AD would require a one-time general visual inspection for contamination of the surface of the upper arms of the main landing gear (MLG) secondary side brace assemblies; and repetitive eddy current inspections for cracking of the upper arms, and related specified and corrective actions if necessary. This proposed AD also would mandate eventual replacement of aluminum upper arms with steel upper arms, which would end the repetitive inspections. This proposed AD is prompted by two reports of rupture of the upper arm of the MLG secondary side brace due to fatigue cracking. We are proposing this AD to prevent cracking of the upper arms of the secondary side brace assemblies of the MLG, which could result in collapse of the MLG during takeoff or landing, damage to the airplane, and possible injury to the flightcrew and passengers.