Airworthiness Directives; Turbomeca Turmo IV A and IV C Series Turboshaft Engines

The FAA is superseding an existing airworthiness directive (AD) for Turbomeca Turmo IV A and IV C series turboshaft engines. That AD is applicable to engines with oil-tank-to-oil-cooler flexible lubrication pipes, part number (P/N) 0 249 92 813 0 or P/N 0 249 92 916 0, installed. That AD currently requires identifying, inspecting, and replacing affected flexible lubrication pipes manufactured after April 1, 2003. That AD also requires initial and repetitive borescope inspections of affected pipes, visual inspections for oil leakage, and visual inspections of the oil filter. That AD also requires that if both engines on the same helicopter each have an affected pipe, replacing one of the affected pipes before further flight. This AD does not contain that requirement. This AD requires the same inspections as the superseded AD and adds inspection of oil-pump-to-intermediate- bearing flexible lubricating pipe, P/N 0 249 92 808 0. This AD also requires all remaining affected flexible lubrication pipes, P/N 0 249 92 813 0, P/N 0 249 92 916 0, and P/N 0 249 92 808 to be replaced as terminating action to the repetitive inspections for those affected pipes. This AD results from additional shutdowns caused by pipes, P/N 0 249 92 808 0, and the introduction of Turbomeca Modifications TU 231 and TU 233 that replace pipes, P/N 0 249 92 813 0, P/N 0 249 92 916 0, and P/N 0 249 92 808. We are issuing this AD to prevent helicopter engine in-flight shutdown of one or both engines resulting in an emergency auto-rotation landing or accident.