Boeing 747 operators are being instructed to carry out prompt elevator checks after a 747-8 freighter was flown without balance weights after maintenance.
The US FAA states that the 747-8F was flown with a right-hand outboard elevator which had been received and installed without the weights.
It says that this absence can lead to buffeting, flutter, oscillation or abnormal vibration which could result in “loss of continued safe flight and landing” – as well as being potentially hazardous to maintenance personnel during installation or removal.
According to the FAA the operator ordered outboard elevators for the left- and right-hand horizontal stabiliser, receiving components with difference part numbers but with paperwork indicating they were interchangeable.
The elevators supplied, however, were not directly interchangeable because did not contain balance weights – they should have been balanced prior to installation and flight.
Boeing issued a 24 April safety advisory specifying procedures – including a visual inspection and examination of records – to check whether the same outboard elevators have been installed on other 747s.
While this advisory applies only to the 747-400 and 747-8 families, the FAA has broadened its directive to include earlier 747 models. It has opted for immediate adoption, and the directive took effect on 5 May.
“Because the affected elevators are rotable parts, the FAA has determined that these parts could later be installed on airplanes that were initially delivered with acceptable parts,” it states.
It says 10 spare assemblies with the relevant part numbers have been delivered to operators since 2022.
Some 170 US-registered aircraft are affected. The European Union Aviation Safety Agency has also published the FAA order as an emergency directive.
