Airworthiness Directives; The Boeing Company Model 737-300, -400, and -500 Series Airplanes

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. This new AD requires replacing the midspar fuse pins with new, improved fuse pins, which would terminate the repetitive inspections. This AD was prompted by a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. We are issuing this AD to prevent damage of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structural integrity of the fuse pins, and consequent loss of the strut and separation of the engine from the airplane.