Enstrom and the FAA have published separate alert notices strongly urging operators of Model 480 turbine helicopters to “immediately” remove any elastomeric dampers and replace them with hydraulic dampers. The action follows a ground-resonance incident on August 5 in Goshen, Ind. The two occupants were “thrown from the helicopter, which was destroyed.” The FAA said preliminary information indicates that the ground resonance could have been caused by elastomeric damper damage, a cracked transmission mount strut or “improperly serviced oleo struts.” Both the FAA special airworthiness information bulletin and Enstrom’s “immediate action required” letter provide pilot procedures if ground resonance is encountered.
Enstrom, FAA Issue Alert on Model 480
- April 9, 2007, 12:39 PM