Jim Scanlon (deceased)
Senior Staff 
FORUM CHAPLAIN
Commander South Texas outpost of the County Sligo Squadron
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Retired: USAF
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Post by Jim Scanlon (deceased) on Jun 17, 2009 0:53:56 GMT 9
When I went to work on the Phase Dock at Minot, I learned a new skill, one that drove many to distraction, but one that needed doing and ended up being one I really enjoyed. The MIXER.
Jim Osteen was the dock/hanger chief when I moved from the flight-line to the dock. It wasn't long before we got a high hour inspection. Jacks under the wings and nose. Elevon locks installed. Tail cone pulled off. Engine rails installed. Engine pulled. Floor boards installed. Drop light hung an turned on. And then......
The big yellow box was checked out of the tool room and it was time for my latest Six training session. Walked across the hanger to the maintenance office to tell Don St.Pierre we were ready. Don was the Convair Tech Rep, and was to be our instructor.
Sound familiar to any of you? Wasn't it fun?
After all the preparation, the checking of the mixer check seemed to be anti-climactic.
One person could do it, but two made the job easier. That first time, I took the big yellow box of pins and Don did the reading of the manual. Each pin had a red flag attached to it so you wouldn't forget to take it out when you were finished with the check. There was a certain sequence that had to be followed in putting the pins in the holes. After the first pin was installed it became a series of pin installations that would tell you if the flight controls were properly set. When you got to a pin that wouldn't go in the hole, you had to take a look to make sure you had put all the others in correctly. If they were properly installed, then the fun began. You got your tools out and adjusted the rod and rod end to the point that the pin would fall in the hole. Then you continued putting pins in and adjusting as needed, until the last pin was in place. At that point you double checked everything and made sure you missed no steps in the sequence the manual called for. When your double check was done, you safetied the rods and rod ends that you had adjusted and called for QC to come take a look. They would come out and climb in to the engine bay and, with flashlight in hand, take a look at the mixer and the pins. When the QC guy was satisfied with the job, you were done. Next step was to take all the pins out and take the elevon locks off. Then it was hook up a hydraulic cart and do a systems check using the protractors to see if each elevon and the rudder moved the proper degrees of travel as you went through the check. If everything went according to the book, you took off the protractors and took them and the big yellow pin box back to the tool crib. By then it would be time for a cuppa joe, or maybe chow time.
Just one more job for the phase crew to perform. In the years I was on the phase dock at Minot, I did a number of mixer checks and alignments. I was always amazed at the engineer who thought that thing up in order for the Six to be able to fly the way the pilot wanted it to.
For the few of you who never worked on a Six, the flight controls were a hydraulic/mechanical system. There were rods, rod ends, turnbuckles, actuators and other mechanical or hydraulic pieces that allowed the pilot to move the stick and the airplane go where he directed it. Much different than the newest generation of planes that use electrical impulses to move the actuators and then the flight control surfaces. There is something to be said for both. But, seems to me, that when you move the stick and there are rods going through the bird to the control actuator that you know what is happening. I'm not too sure about the wire that carries the impulse. However, there are lots of birds out there using the wire system and it works.
I don't know if it took a genius or a madman to design the mixer. Maybe a bit of both.
:god_bless_usa
In GOD we Trust.
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Post by Jim on Jun 17, 2009 5:03:39 GMT 9
AH yes the mixer assy!!!!!!!!! For the 27thFIS AFCS troops  , for the Ma-1 eenies ......transitional movements in and out of AFCs were corrected by people who didn't know jack$hit about flight controls- they would make their adj at the HRP or the HEP inputs to a flight control system that was delivered out of Convair OUT OF RIG!!!!!!!!!!!!! ;D ;D After repeated threats to kick the $hit out of the next guy I saw opening the access panels to either of the systems, I took the a/c into the hangar and disconnected every push-pull rod from every bellcrank,walking beam or other pivot point and installed every rig pin from the stick and rudders to the mixer, then neutralized and locked the surfaces in neutral, disconnected the actuators from the surfaces (This is when we found out that the actuator attach bolts on the surfaces were over torqued-see a previous post of mine having to do with 300 PE Insp req'ts) If memory serves me, there were a total of 45 pins required and 3 protractors used. At this time -1960, we at Loring established the first flight team that worked all flight control discrepancies. It consisted of myself from QC, Roger Matthews, convair rep, AFCS NCOIC, a PE Dock Chief, and a sharpie from MA-1..............I even weighed the a/c to make sure we weren't having a remotely connected CG problem............ We then had to adjust every rod end and turn buckle on that airplane to get the attach bolts to slip in.............With the mechanical and hydraulic systems rigged to neutral, the electronic whizz kids were allowed to do their magic...... BTW, The duece also had a mixer assy.......The T-38 and F-5 (all variants) had a form of the mixer as well.................All of this took place before the phase system was implemented...........We were using the card system rather than the book style along with the flow chart- it worked IFFFFFFF you could get the clowns in job control would cooperate........ :drunk :drunk :drunk The Old Sarge |
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Post by dude on Jun 17, 2009 10:51:39 GMT 9
 Evidently whatever problems the MA-1 may have caused back in the 60's must have gotten worked out by the 70's. I never had to have an engine rolled back to work an AFSC problem. In fact, the only time I saw and aligned the elevon pots was during phase checks. (A lot of times we would just go ahead and replace them while we were there.) The Pitch G Limiter was often the reaons for a transitional failure to dampers. But the TRT was solid as a rock. Most AFSC problems were up front in the 821 or the Flight Mode Panel (063?). By the time I was on the plane we could align the 821 by hooking up a mule and running AFSC routines on the computer. We could also independantly monitor the p, y and r signals using the octal readout on the 846 to set up the 821 pretty tight.
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sixerviper
F-106 Skilled
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Post by sixerviper on Aug 11, 2009 6:04:41 GMT 9
Even though I was an Instrument weenie and never worked AFCS on Sixes (I did on Thuds and Vipers...), I now remember the protractors on jets in phase. I had totally forgotten about them. I would have LOVED to do one of those rig checks!! I bet that was a fun job and it would keep you INDOORS on a cold winter's day at Minot!!
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615crewdog
F-106 Qualified
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Post by 615crewdog on Sept 6, 2009 9:05:41 GMT 9
I got involved on one of those alignment checks once at Tyndall. My dock chief was told during the pre-dock meeting that the jet had a flight control problem causing it to want to roll to the right during flight. The pilot could null out the roll with the trim button but they wanted us to check the rigging from the stick to the mixer assy.
Well we aligned everything according to the T.O. and had QC sign off on the rig and the rest of the inspection and then sent the bird out for the FCF.
Thats when I learned that you could actually align everything perfectly and still not fix the problem. After the FCF the pilot said that it took full left trim and a lot of left stick to get the jet level enough to land it.
We had to go back through the entire rig again. Every pin dropped in place as it should have. Then someone told my dock chief to do a string check to check that the airplane itself was aligned. It was so far off that we had to realign the mixer and elevons to the NEW neutral position and then the jet flew great.
Turns out the jet had been over "G"d and had actually twisted the right wing. The New neutral position 1/2 inch above the normal position.
Sometimes even the book won't tell you everything to look for.
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Evidently whatever problems the MA-1 may have caused back in the 60's must have gotten worked out by the 70's. I never had to have an engine rolled back to work an AFSC problem. In fact, the only time I saw and aligned the elevon pots was during phase checks. (A lot of times we would just go ahead and replace them while we were there.)
