Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 777 airplanes. This proposed AD was prompted by reports of corrosion damage on the outer diameter chrome surface of the horizontal stabilizer pivot pins. Micro cracks in the chrome plating of the pivot pin, some of which extended into the base metal, were also reported. This condition, if not corrected, could result in a fractured horizontal stabilizer pivot pin, which may cause excessive horizontal stabilizer freeplay and structural damage significant enough to result in loss of control of the airplane. This proposed AD would require replacing the existing horizontal stabilizer pivot pins with new or reworked pivot pins having improved corrosion resistance, doing repetitive inspections after installing the pivot pins, and doing corrective actions if necessary. We are proposing this AD to correct the unsafe condition on these products.