The operators of Hawker 800 business jets with winglets have received a service bulletin from winglet manufacturer Aviation Partners instructing them not to fly the midsize aircraft above 34,000ft (10,370m) until a modification is applied to prevent possible roll oscillation.
The US Federal Aviation Administration is expected to make the SB an airworthiness directive, but it has not yet done so.
The manufacturer said: "Aviation Partners and the FAA consider this SB to be a safety-related limitation until a design change to preclude the oscillations is developed and FAA approved."
AP's chief operating officer, Hank Thompson, explained that the company believes it has found a solution involving rebalancing the ailerons, where the oscillation tendency had originated.
Extensive ground-testing under all anticipated circumstances has given AP confidence that flight-testing will prove the solution, following which the FAA will be presented with the results for approval.
AP believes the modification should be cleared in about a month, after which it can be applied. The company has not provided an estimate of the time the modification work would take.
Source: Flight International
