Winglet manufacturer Aviation Partners has completed a test flight with a Hawker 800 featuring a new winglet installation that was tweaked to prevent aeroelastic flutter.
The original Aviation Partners winglet was the source of several reports of Hawker 800s that experienced wing and aileron oscillations.
Those reports prompted the Seattle-based company to issue a service bulletin last month restricting flights of a Hawker 800 equipped with the aftermarket winglet above 34,000ft (10,400m).
In the meantime the company re-considered how the winglet interfaces with the aileron as it is installed on the aircraft. Using the finite element method, Aviation Partners recreated the oscillating symptom in simulation and analysed all of the triggering scenarios.
Aviation Partners found that shifting the mass balance of the aileron forward of the hinge line dampens the oscillating cycle in every one of the scenarios, says Aviation Partners chief operating officer Hank Thompson. Aviation Partners then presented the results to the US Federal Aviation Administration.
"We sat for several hours going through lots and lots of cases and the FAA expert was as convinced as we were," Thompson says.
Aviation Partners still has to validate the analytically-based conclusions with the 3 June flight test. If the flight test confirms the Aviation Partners solution, the FAA could certificate the fix as soon as the end of the his month, Thompson says. Aviation Partners already has kits standing by to distribute as soon as the FAA approves the certification documents.
The FAA issued a supplemental type certification on 8 July 2004 to Aviation Partners to install the aftermarket winglet on the Hawker 800 - a mid-size twin-engine business jet. The modification also has been approved for the Hawker 800A, 800B and 800XP models.
Source: Flight International
