Mods please move if appropriate..
The latest letter from NZ CAA (states that is not from a manufacturing defect.)
26 May 2015
Dear Sir/Madam
DCA/R44/32B Robinson R44 Main Rotor Blades P/N C016-7 – Failure initiated by fatigue crack
As the registered owner of an aircraft that is possibly affected, you are advised of the following.
On 23 January 2015 a significant crack was found in a P/N C016-7 main rotor blade fitted to a Robinson R44 Raven II helicopter on agricultural spraying operations.
During a spray run the pilot experienced vibration through the cyclic control. The vibration increased when the helicopter was brought to the hover. The pilot immediately landed the helicopter and found a signification crack in one of the main rotor blades. The photograph in DCA/R44/32B shows the area where the crack was found. No main rotor blade defects were found by the pilot during any preceding pre-flight inspection(s).
Both main rotor blades were subsequently removed and shipped to RHC for examination. This examination was undertaken with oversight from the National Transport Safety Board (NTSB), the Federal Aviation Administration (FAA) in the USA, the Transport Accident Investigation Commission (TAIC) and the CAA of New Zealand.
The preliminary investigation determined that the main rotor blade failure was due to a 50mm fatigue crack initiating at the trailing edge of the blade. The time taken to progress to this length is unknown. Once the crack reached 50mm the remaining blade cross-section began to fail rapidly in a combination of fatigue and overload (mixed). Finally the remaining section failed in overload once the blade chord had reduced to approximately 50% of original.
The original fatigue crack was not due to a manufacturing defect.
The multi-agency investigation is ongoing and if any other significant information becomes available further communication will follow.
To assist the CAA with this investigation please report any Robinson R44 Main Rotor Blades P/N C016-7 incidents or defects to the CAA by completing a CA005 Defect Report form. Please provide as much detail as possible. The form can be obtained from
http://www.caa.govt.nz/Forms/CA005D_Form.pdf
The completed form can be emailed to the CAA at
[email protected]