October 25, 2013
The FAA today ordered Boeing 747-8 operators to check elevator power control actuators (PCA) for missing bushings after a report of a missing bushing on an in-service aircraft.
The directive, effective Nov. 12, was adopted without prior public comment due to the risk presented. It requires operators to follow the recommended detailed inspection procedure and timeline detailed in a Boeing Alert Service Bulletin issued Aug. 23. The order does not provide additional compliance details.
“Any airplane that is missing a bushing in the elevator PCA installation is operating at an unacceptable level of risk,” the FAA says in the directive’s preamble. “If the bushing is not present, the stiffness of the load path will be decreased, which will cause wear of adjacent parts and increased free-play of the elevator surfaces.”
The FAA says an operator discovered a missing bushing while probing “unusual noise” from the left inboard elevator during a ram air turbine functional check. “When investigating the cause of the noise, the operator found too much free-play in the left inboard elevator, which was traced to a missing bushing in the PCA installation,” FAA explains.
The operator discovered that the left inboard PCA was disconnected to correct pre-delivery damage, FAA says. “When the PCA was reconnected, however, the bushing was not installed.”
The directive covers only nine U.S.-registered aircraft, but is expected to be adopted by other regulators. So far, Boeing has delivered 56 747-8s, including 39 freighters.
[Editor’s note: This story is updated to correct the number of incidents reported.]