To: Chips
In my original postings about the certification of the R22 and the R44 the main thrust was regarding the rotorhead design and how I felt it was the major cause of the in-flight rotor loss due to mast bumping and or fuselage incursions by the rotor blades. The chart reflects 23 such accidents. My report reflected 31 such accidents and last year that total rose to 35. This type of accident is analogous to a fixed wing aircraft suffering a loss of one or both wings. So, when you figure this type of accident on a fixed wing aircraft the rate of occurrence would be almost nil per 100,000 flight hours. Bell helicopters had suffered 53 mast separations when I first became interested in this phenomena in 1976. They have most probably suffered several more since that time but I honestly do not believe that any of the accidents other than the Robinson on the chart resulted from fuselage strike or mast separation.
FAR-AC-1309-1A states that all single point failures that could cause death or loss of the aircraft must be designed out of the system. If the design can’t be altered then the frequency of occurrence of death or loss of the aircraft shall occur no more frequently that 1 10-9 hours of accumulated flight for the specific model of aircraft. If in fact the rotorhead design on the R22 and R44 are determined to be defective then the Robinson design does not meet those criteria.
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The Cat
[This message has been edited by Lu Zuckerman (edited 25 February 2001).]
[This message has been edited by helidrvr (edited 25 February 2001).]