On December 20, 1999, a Hughes OH-6A (registration N72LC) was involved in an aviation accident near Fort Myers, FL. Investigators recorded the probable cause as: improper maintenance inspection of the helicopter by unknown maintenance personnel, resulting in a worn control rod bearing being continued in service, and subsequent separation, resulting in an in-flight loss of control and a crash. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A Lee County Sheriff's Office helicopter crashed into a building after a lateral control rod end fitting separated. The bearing did not move freely and a rivet was missing, with aluminum oxide deposits found.
Witness Observations
Witnesses reported that the Lee County Sheriff's Office (LCSO) helicopter flew over the landing area and was on downwind when it suddenly turned to the right. The helicopter then descended at a high rate of speed in a nose-low attitude and impacted a building.
Postcrash Examination
Examination of the wreckage revealed that the lateral control rod end fitting had separated from the control rod. The fitting's bearing did not move freely when compared to a normal rod end bearing. Additionally, the rivet that normally passes through the lateral control rod and rod end fitting was missing. Dark and white deposits were found in the threaded region of the rod and rod end fitting. Laboratory analysis determined that these deposits were aluminum oxides.
Maintenance History
Maintenance records indicated that the control rod had been inspected and modified by Heli-Tech when the helicopter was first acquired. The helicopter was delivered to the LCSO at about 3,546 total flight hours. Following receipt from Heli-Tech, the operator's maintenance log did not show any specific maintenance entries related to the control rods. At the time of the accident, the helicopter had accumulated 4,419.4 flight hours.