To: helmet fire
Many of your objections to my comments are based on your knowledge of Bell flight theory and using that logic; you question or object to my postings about the Robinson.
The following is extracted from the R22/R44 POHs, as the information is the same for both helicopters.
This is a statement appearing on the last page of section 4 of the respective POHs. The page is unnumbered and the material contained on this page was published in accordance with a FAA priority letter AD dated 13 January 1995. For brevity sake I did not reproduce those things that could result from Zero G as they also apply to the Bell system. It addresses Mast Bumping.
…High forward speed, turbulence, and excessive sideslip can accentuate the adverse effects of these control movements. The excessive flapping results in the main rotor hub striking the main rotor mast with subsequent main rotor separation from the helicopter.
Below that statement are 5 items that should be avoided in order to minimize high flapping loads. Statement (4) reads, Avoid sideslip during flight. Maintain in-trim flight at all times.
I now extract material from Safety Notice SN-11 that applies to both helicopters. …. During the low-G condition the lateral cyclic has little if any effect because the main rotor thrust has been reduced. Also there is no main rotor thrust component to the left to counteract the tail rotor thrust to the right and since the tail rotor is above the CG the tail rotor thrust will cause the helicopter to rapidly roll to the right. If the pilot attempts to stop the right roll by applying full left cyclic before regaining main rotor thrust, the rotor can exceed its flapping limits and cause structural failure of the rotor shaft due to mast bumping or allow a blade to contact the airframe.
It continues. The best way to prevent mast bumping is to avoid abrupt cyclic pushovers during forward flight. Always use gentle sensitive cyclic control inputs, and if you do have a feeling of weightlessness during a maneuver, gently bring the cyclic aft to regain main rotor thrust before
Applying lateral cyclic.
The POH says to bring the cyclic back without adding any lateral cyclic. Tim Tucker who was a test pilot during development of the R22 also teaches many safety courses. He tells the students to add a tad left cyclic when pulling back on the cyclic to load the main rotor. No other instructor has his experience or technical background and in their ignorance or whatever they follow the instructions in the POH. If it can be proven at some later date that the 18-degree offset of the control system is a factor it can be proven that Tim Tucker was right and if you did the control movement in accordance with the POH you could increase the right roll rate. A highly experienced pilot could possibly recover from this situation. However if a newbie enters this condition he will most likely instinctively push the cyclic left and chop off his rotor or the tail boom.
I have one question. How many Bell Helicopters have a restriction against sideslip and out of trim flight?
[ 28 October 2001: Message edited by: Lu Zuckerman ]
[ 29 October 2001: Message edited by: Lu Zuckerman ]
[ 29 October 2001: Message edited by: Lu Zuckerman ]