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CH-46As Breaking up in Flight!!!

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  • #16
    Joe, This was last in the hover aft block acft. Troubleshooting not a real problem, our biggest problem was convinceing the non 46 pilots, 34, UH/AH1 and converted fixed wing guys that there NO Tracking promblem in the acft. We would get an aft head beat gripe about every 4/5 flights from those that had little knowledge of hover aft.
    top A

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    • #17
      Walt,

      I stand corrected on the BU Number. I never did, nor would I now, argue "data" you you.

      My Phrog, ET-38 / 152565 was the second to launch on the emergency recovery. By the time we got to the crash site, Bill Clover had been picked up still alive and taken to the Med-Pad. There was debris floating everywhere and we were instructed to pick up as much as possible. We did a water landing, taxied around like a motorboat, I hung out of the starboard door by my gunner's belt. I grabbed as much debris as possible and handed it back to whomever the other crewman was at that time.

      Finally the pilot said that we were too sluggish and had to get out of the water. We almost didn't get airborne, ended up taking off like a seaplane and flew just above the water to get back. When we finally parked on the Flight Line, I noticed a HUGE puddle of water under my A/C. We had been washing out my A/C when the call went out for first the available aircraft to launch. Mine was one of the aircraft closest to the OPS Shack, so a couple of pilots jumped in and away we went. We were so intent about getting out there to help our brothers, we did not even do a pre-flight.

      Now, you have probably already guessed why the bird was sluggish in the water and the reason for the large puddle when we came back --- THE DRAIN PLUGS WERE STILL OPEN FROM WASHING OUT THE A/C.

      You or Big "O" didn't know about that one did ya, Walt?? Who cares now? All we wanted to do was get out there to help. But when all is said and done, we were too late.

      SEMPER FI

      Jake
      Joseph "Jake" Jacobs
      HMM-262 Combat Helicopter Association

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      • #18
        It happens Jake Forest Gump said so. Ask "Big O " about the heater cover as it flew by Mr. Fogg's head on the day of the fly over on the Cruise. SF

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        • #19
          Rosser

          The guy standing with me, Gerry Rosser, was flying wing on one of the SVN Aft Pylon failures.Don't remember now if he told me Ky Ha or Phu Bai area, but early '67 time frame HMM-165. Rosser has dropped off the face of the earth. Anybody seen or heard from him??
          Semper Fi
          Joe

          http://pic12.picturetrail.com/VOL431...6/17504379.jpg
          Semper Fidelis
          Joe


          Phu Bai tower:
          YW-11 for Phu Bai DASC-
          Remember, These are "A" models!
          YW-11 BuNo-151939
          '65 Model CH-46A

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          • #20
            I think it might have been ET 27 unless I am wrong I think he was in 262. I'm not sure its the same Rosser , but I remembered the name and I looked in the cruise book and there is a picture of a Cpl. G. Rosser.

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            • #21
              Desyncs annd Hover Aft

              I started at Boeing in September 1967 as an Engineer in Flight Controls and it seemed like everyone in the place was involved in some way in the breakup problem. Internally it was known as "desync". There was no easily definable cause which could be blamed for what happened which makes a solution much harder to find. As one of the earlier posts mentioned there was no single cause for all the accidents. But if anything happened to cause a "desync", a transmission failure or loss of a blade, for instance, the structure usually failed at station 410. If 410 was beefed up then the failure moved to the next weakest point. The ultimate solution was to prevent the failure that caused the "desync" in the first place, some as simple as making sure the pins in the lower ramp were clean and were all the way in. A pin not seating could put stress on the whole back end. Joe Reed mentioned once that I had apoplexy when he flew with the ramp open. That's why.

              Boeing threw immense manpower at the problem and they approached the task from many different directions. One of the approaches was to say OK, so a desync happens, what do we need to do to make the accident survivable. First, sensors would be fitted to each rotor head and if the rotor rpm differed by more than a given amount it could be assumed that a desync was about to happen. So far so good, now it gets a bit wild. To prevent the rotor blades from colliding. the rotor planes had to be tilted back, way back. And it had to be done in milliseconds. That would make engaging hover aft at 140 knots seem like a gentle manouvre. But we haven't finished yet. The pilot's reaction to this would be to come forward on the cyclic as fast as possible. Can't allow that, so we disconnect his controls. So here you are, the airplane standing on its tail and no flight controls. You wouldn't have to crash, everyone would be dead from heart failure. Fortunately this proposal died, especially when a quick reliability analysis showed the cure to be worse than the problem. I think the final word came from Flight Test. They wanted to know who we were going to get to test fly this dog since they had no interest in doing so.

              Hover Aft in the 'A' model was a manual trim that tilted the rotor plane back allowing the fuselage to remain closer to level on approach. Without it, the nose gets awfully high in a fast approach. It was placarded against use above 70 knots. But pilots found that engaged at cruise it acted like a speed brake. Combined with another unauthorised manouvre, the Buttonhook, it was amazing how quickly one could get into a hot LZ. We'll fix that says the factory, we'll install an interlock so you can't engage it above 70 knots. Oh yeah, says the pilot, watch this. All I have to do is stick my hand out of the cockpit window and the airflow to the pitot tube is masked enough that it seems like I'm going less than 70 knots. In my opinion, it would have been better to have made it possible to engage Hover Aft, it was so effective the pilots would use it anyway if they had to. Needless to say, this opinion was not received kindly by the factory.

              By the way, the Chinook was designed by the same people who designed the H-46. It has the best safety record of any helicopter. #2 is the H-46.
              Last edited by jdullighan; 11-02-2004, 23:03.
              John

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              • #22
                Interesting Hover Aft incident the summer of 69 with HMM-265 while on the Iwo Jima. Got the info about the initial flight second hand from a crewman. During an approach to MMAF, or where ever, the Hover Aft didn't kick in when applied and the pilot ended up with the stick in his belly. Of course, just prior to touch down the heads programmed back as advertised and a fun ride was had by all but with a safe arrival. The approach to the ship was of great concern but at least the excursion was anticipated. The gripe was written up, the 40 knot relay was found to be defective and the speed trim box replaced. Now the test hop. I asked the pilot if he was ready to take her up and the reply was "No way!!". I then suggested testing the offending system at 5000 feet and I would accompany him. That he agreed to. We lifted off the Iwo, cruised up to 5000 feet a few miles off the coast of MMAF and proceeded to do practice landings. (Fixed wing pilots just don't understand an altimeter at 5000 feet with an airspeed of 0. Just a comment.) Everything functioned correctly and we flew home.

                Wayne Stafford

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                • #23
                  The famous "buttonhook" approach

                  Right you are John!
                  We sure could get in an LZ in a hurry if we were loaded lightly enough to recover from the maneuver (or if the approach speed was reasonable enough). As a Crew Chief I wasn't ever quite a good enough stick to really fly a buttonhook approach, although I have made some landings with and without hover aft, with HAC approval, to see what the difference was. On the really smooth, quick ones it was a blast!!
                  John, THANKS for keeping my Aft Pylon on YW-11! We needed it!!
                  Semper FI
                  Joe
                  Semper Fidelis
                  Joe


                  Phu Bai tower:
                  YW-11 for Phu Bai DASC-
                  Remember, These are "A" models!
                  YW-11 BuNo-151939
                  '65 Model CH-46A

                  Comment

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