To: RW-1 and all
You keep insisting that you are never going to darken these threads and then you come back as if you were attached by a bungee cord. Either stay away or stick with it and we can exchange ideas. We may not agree but it helps stimulate the dialog for others to join in.
I figured this part was going to be a private email conversation between RW-1 and myself. This is related to RW-1s comments about my qualifications not meaning squat. He sent me an email telling me how he operated under extreme conditions and had among other things been suspended under a Huey while strapped to another person. If you read his website he states that he was involved in SAR activities. In his email to me he stated that he had done it for 9 years in the US Navy. I sent him an email describing my experiences in the US Coast Guard that were at least equal if not greater than his and, I did it in 6 years. He also stated that since I was not a pilot I should have no say on a forum such as this. In my email to him I stated that I had 1400 hours as a flight engineer and many other hours as a flight mechanic on helicopters. I told him that I flew every aircraft that I was assigned to and that although I didn’t say it I had more stick time than he did.
Now, we get back to RW-1s comments in this thread. I told him repeatedly that if I had direct access to an R22 I would conduct the tests to determine if there was actually an 18-degree coupling. He constantly refers to what a good engineer would do and that is, to perform the tests himself to verify the findings in my report.
Two points, 1) since I didn’t perform the tests to prove I was correct then, as a good engineer why doesn’t RW-1 perform the test to prove I was incorrect and 2) the report itself.
The report was written and submitted to the NTSB to question the design of the R22 and the R44. I made certain technical statements as to my feelings about the design. I referenced each point to the FAA Certification of Normal Category Rotorcraft Advisory Circular (AC-27-1). At the end of the report I posed a series of questions that were directed to the FAA and Robinson. It was these questions that would have supplied the answers I seek. It was not my intent to get plastered by everybody that did or thought that they knew more than I did on these threads. When I offered a copy of the report to the NTSB, it was my intent to get both Robinson and the FAA to explain how and why the R22 was certified.
In answering the first question on these forums I exposed myself to individuals like RW-1 that totally disagreed with my point of view yet when I asked him (them) to give me an explanation that did not parrot Frank Robinsons’ words they themselves were at a loss for words. The questions in the report were in some cases couched to get a further explanation and not to expose my ignorance on the subjects being questioned. For those of you that have never read the report here are those questions. RW-1 how many of these questions can you answer?
Addressed to: Question:
Robinson / FAA If the certification procedure requires that normal category rotorcraft demonstrate the capability of flying at side slip angles of ten to ninety degrees, why are the R-22 and R-44 helicopters restricted from flying at any side slip angle and why must the pilot keep the aircraft trimmed at all times? What problems would manifest themselves if a side slip angle were introduced? If a problem does exist, how did the R-22 and R-44 successfully meet these certification requirements?
Robinson / FAA Is there any restriction as to what forward speed the pilot can apply full right or left cyclic? If such a restriction exists, what is the reason/justification for the restriction? In the application of full left or right lateral cyclic, what would happen if the pilot introduced an aft component to the left lateral or a forward component to right lateral (assuming the maximum forward speed at which the application of left or right lateral cyclic input can be made)?
Robinson / FAA The pilots handbook advises that when countering a "Zero G" situation the pilot must be careful to pull the cyclic straight back. The pilot is told not to try to counter the right roll induced by the tail rotor. What would happen if in pulling the cyclic back the pilot introduced a heavy right roll component?
Robinson / FAA At what forward speed would the pilot be cautioned not to pull the cyclic straight back? If such a restriction exists, what is the justification? If the pilot can pull the stick rearward, what would happen if in doing so the pilot introduced a right roll component? What would happen when the pilot performs a cyclic flare during auto rotation and he/she introduces a right roll component?
Robinson / FAA How much of a pitch angle (collective) must be introduced to stall the main rotor (assuming gross weight and air density are within acceptable limits)? Assuming high collective and maximum cyclic application, at what point would both blades or one blade stall? Assuming the pitch angle at stall could be measured, where would that measurement be taken (blade station)? Does this stall angle vary at different altitudes and gross weights?
Robinson What is the purpose of tail rotor precone?
Robinson What are the demonstrated MTBFs on the following:
1. Main rotor flapping bearings?
2. Main rotor teeter bearings?
3. Tail rotor pitch bearings?
a) inboard
b) outboard
4. Main rotor bearing packs?
What are the modes of these failures?
Robinson What percentage of main rotor heads reach their design life? Of those that are removed, what are the primary modes of failure and which components have the highest rates of failure?
Robinson What can happen if the high and/or low swash plate adjustments are exceeded?
Robinson / FAA Why are two bladed rotor systems susceptible to "Zero G" maneuvers and three or more rotor blade systems are not? Why was a two bladed system selected over a multi-blade system for use on a helicopter that would be operated by pilots who have minimal "stick" time or students learning to fly helicopters?
Robinson / FAA What was the rationale for designing a rotor system that has offset flapping hinges along with a "teeter hinge"? What are the advantages and disadvantages of this design over a system that can flap and not teeter or a system that can teeter but not flap. How are lead-lag loads reacted during rotor flap? Do these in-plane loads cause premature wear-out of the "teeter" bushings or high cycle torque reversals on the main rotor shaft and rotor "teeter" through bolt? Can these oscillatory loads cause bending of the blade and induce a tucking of the blade tip?
Robinson / FAA According to AC-27-1 and CFR-14.21.16, the design of the R-22 rotor head is "novel or unusual" which requires very special care in the certification process to verify the efficacy of the design. Was this very special care exercised during the certification process?
Did the FAA note that the design of the rotor system precludes the helicopter from being sideslipped because of very high flapping loads which could result in blow back and/or fuselage strike? Did Robinson instrument the rotor per certification requirements and, if so, did the R-22 and/or the R-44 pass the sideslip test? If they did pass the test, why are both aircraft restricted from being side slipped?
Robinson / FAA Why are the degrees of blade twist different between the R-22 and R-44, where the R-44 blade is longer and the tip speeds are almost the same?
Robinson / FAA What would happen to the swash plate assembly, if during certain cyclic applications, the "uniball" bearing were placed in a bind?
Robinson / FAA Are the cyclic stop plates the same on all R-22 models? If they are, how can you get different cyclic angles on the Alpha and Beta models if the control "throws" are the same as those used on the R-22 and R-22 HP models?
Robinson / FAA Why was the seventy-five percent point selected to measure pitch angle? Why are blade angles averaged instead of setting an optimum low collective blade angle for both blades and use the stops to control the range for cyclic control? Why was the system selected over adjustable stops that are used to limit over control of pre-established rigged ranges? In other words, why is the Robinson design different from every other helicopter?
FAA Why did the FAA certify the "novel or unusual" rotor head design, when at some point in the certification process, it would have been determined that the rotor could not meet the requirements of the certification process?
RW-1 if you are out there, I am waiting for your response.
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The Cat
[This message has been edited by Lu Zuckerman (edited 03 January 2001).]
[This message has been edited by Lu Zuckerman (edited 03 January 2001).]