From the FAA’s Accident/Incident Data System (AIDS), through its Aviation Safety Information Portal, as reported. The NTSB investigates accidents separately, and its record of an accident is the fuller one. The aircraft is matched to the registry by N-number and event date, checked against the reported make and model; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Helicopter on maintenance test flight developed severe vibrations with one engine idled. Unable to keep rotor RPM.
As the FAA filed it
HELICOPTER ON MAINTENANCE TEST FLIGHT DEVELOPED SEVERE VIBRATIONS WITH ONE ENGINE IDLED. UNABLE TO KEEP ROTOR RPM.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.