The flight crew of a Dutch registered Boeing 767-300 ER airplane reported that during landing rollout, as they applied the brakes, they noted a significant airframe vibration, and a
<p>pronounced rumbling noise. During a postincident inspection, maintenance personnel
discovered a broken landing gear pivot pin on the right main landing gear truck. The landing
gear bogie pivot pin was removed from the incident airplane's main landing gear bogie beam.
A residual amount of dried grease was noted on the fractured pivot pin and associated bogie
beam bushings. A senior materials engineer from the NTSB's Materials Laboratory reported
that most of the chromium plating was missing from the pin's shank, and the underlying steel
was worn, corroded, and displayed signs of heat damage. He noted that the originating
fracture region contained corrosion pits. The fracture features noted are typical of stress
corrosion cracking. The airplane's flight data recorder (FDR) showed that the incident landing
was within normal operating tolerances. On April 8, 2004, Boeing Commercial Airplane
Group issued Alert Service Bulletin 767-32A0199, which requires the replacement of the
current pivot pins with pins made of a different type of steel. According to Boeing Commercial
</p>
Airplane Group, the new steel is more resistant to heat damage, and less susceptible to stress corrosion cracking.
NTSB
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