NTSB Identification: WPR09IA070
14 CFR Part 91: General Aviation
Incident occurred Saturday, December 27, 2008 in Kamuela, HI
Probable Cause Approval Date: 12/29/2009
Aircraft: MD HELICOPTER MD 900, registration: N902AF
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
A witness informed the flight crew that the helicopter "lost a panel" during landing. Inspection of the helicopter revealed that the lower right stabilizer (endplate) separated and was located approximately 70 feet from where the helicopter landed. The endplate was later recovered; however, the two associated attachment bolts were not. Without the bolts, it could not be determined if the attachments were not properly torqued or if the bolts' locking mechanism was no longer serviceable. The operator reported that the endplate was removed approximately 42 flight hours prior to the incident to facilitate a maintenance action on the horizontal stabilizer. Following the maintenance action and inspection, the endplate was reinstalled using the original attachment bolts. The applicable maintenance manual instructions for endplate installation directed maintenance personnel to secure the endplate to the spar tube and torque bolts to a specified value; however, it did not direct maintenance personnel to apply sealing and locking compound to bolt threads prior to installation. Following the incident, the manufacturer issued a mandatory Service Bulletin requiring the inspection of endplate bolts for serviceability and application of thread locking compound.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The separation of the endplate bolts for undetermined reasons, resulting in an in-flight separation of the right endplate. Contributing to the accident was the manufacturer's failure to provide sufficient guidance for endplate bolt installation. Full narrative available
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