The FAA issued a special airworthiness information bulletin (SAIB) NM-14-05 related to potential wing/aileron oscillations on various BAe 125/Hawker business jets. The November 27 bulletin covers the following types: the 750, 800, 800A (including C-29A and U-125/U-125A versions), 800B, 800XP, 850XP, 900XP, 1000, 1000A and 1000B.
The FAA has received reports of wing/aileron oscillations on the Hawker 800XP and 850XP at altitudes above 33,000 feet and at speeds of more than Mach 0.73. The oscillations were not divergent, and when the crew reduced speed and took the aircraft below 30,000 feet they ceased.
Investigations revealed missing aileron bushings, low cable tensions and improperly installed brackets on the aircraft concerned. After the operators corrected the airplanes to the type design configuration, as defined by the existing maintenance manuals, the oscillations did not recur.
In its bulletin, the FAA recommends a one-time maintenance check at the earliest opportunity to verify that all the bushings in the aileron and aileron tab assemblies are installed correctly, that the free play is within the limits specified in the maintenance manual and to ensure the hinge brackets are properly installed and the cable tensions are correct. The agency strongly recommends that maintenance be done at regular intervals, as per the maintenance manual.
Reports of any wing oscillations can be e-mailed to firstname.lastname@example.org.