To: NickLappos and anyone else that will listen.
Regarding what a helicopter must demonstrate I provide the following.
AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip (out of trim) of plus 10-degrees, left and right (at 0.6 VNE) and CFR-14-27.351 requires full deflection of the tail rotor pedals while airborne from 0 to 0.6 VNE to attain a ninety degree side slip (left and right).
I goofed by saying 0.68 VNE
Let's assume that Robinson demonstrated these requirements and the FAA approved the demonstration. When the Robinson R-22 started falling out of the sky minus their rotor the NTSB became involved and recommended the de-certification of the helicopter. The FAA refused for whatever reason. I personally believe that they had to save face for granting the certification.
The FAA contracted with Georgia Tech the same school that NickLappos attended requesting that they determined what was the root cause of these accidents. They determined that when the helicopter was flown out of trim or placed in a sideslip there was a resultant high degree of flapping of the main rotor resulting in mast bumping and/or rotor incursion. As a result the FAA issued a priority letter to Robinson outlining the causes of the accidents and several procedures that had to be eliminated to prevent the mast bumping and rotor incursions. Two of the maneuvers to be avoided were side slipping and flying out of trim. These were the same maneuvers that had to be demonstrated for certification. From this I drew the conclusion that if the R-22 were presented at this time for certification with these same restrictions the FAA would not grant certification. Maybe I’m wrong but that is my opinion. You are entitled to yours.
Regarding my addressing the rigging procedures it had absolutely nothing to do with an 18-degree offset or anything related to it. The rigging procedures are wrong and are totally different from any other helicopter. Before accusing me of being wrong I suggest you familiarize yourself with the rigging procedures.
Another point to consider relative to the blade cracks when the blades flap about the cone hinge they will lead and lag. Since there is no vertical hinge the lead lag loads will be reacted by the cone hinge. These loads must pass through the blades so the blades are subjected to inplane bending at a very high frequency resulting in fatigue (IMHO).
Still another point to consider that the R-22 unlike other helicopters,which are certified by the helicopter certification branch in Texas was in fact certified by The Los Angeles Aircraft Certification Office of the Transport Airplane Directorate. Is there a possibility that this office had no knowledge base relative to helicopters and did not fully understand the certification requirements? Just a thought.
I did not hijack the thread. I responded to what VFRpilotpb had stated and it went from there.
