Last month, I completed the first Condition Inspection on the Valkyrie, so naturally, this month, I had a failure....The past couple of weeks, I have noticed a stiffness to the mixture control, and in the last couple of flights, it got progressively worse - but still functional. It seemed to get better as things warmed up, and I went so far as to remove the cowl last week, remove the cable from the carburetor, and make sure the carb wasn't stiff. It wasn't, and by that time, it was working smoothly.
Today, I went to start things up, and it was very stiff to get into full rich for start. I figured it would act like last week, and get better as it warmed up. Instead, when I went to lean, it was essentially locked in the full rich position (if it's going to fail locked, that's a good place to be!). AS it was not a safety issue at this point, and I was only flying across town to an RV Builder's lunch, I continued, leaving it full rich and shutting down with the key. The flight home was uneventful in full rich.
My passenger today was RV-8 builder William Slaughter, and I have to thank him for being interested enough to hang around and help me with the troubleshooting and diagnosis. (Of course, he mentioned something about "honey-doos" needing to be done if he returned home...) We de-cowled, and disconnected the cable at the carb - the carb was free, the cable was not. We cut some cable ties and clamps, and stretch the cable out straight - still extremely stiff from the cockpit control. I have dreaded the thought of taking apart the throttle quadrant, because frankly, once you get it all in place, getting it out can be a real chore - but that was the next step. I got the cable end off of the lever, and the cable was still virtually unmovable - so there was nothing to do but remove it from the aircraft. To make that easier, we took the forward baggage floor out. (Anyone keeping track of how much re-assembly I have to do....?)
Taking the top off of the throttle quadrant, I was able to get a stubby wrench on to the nuts that held the cable housing to the quadrant bracket, and with some not-do-gently pulling from the front, the cable was out - about an hour from the start of disassembly. The cable is essentially frozen in the sleeve, and it appears to be from a spot where the cable had been riding on the muffler hanger (the piece of radiator hose). It had worn through the plastic jacket of the mixture cable, and started to wear away the metal housing. I have not dissected it yet, but I suspect that the cable was crushed in some way, and has damaged the core.
The lesson here is that just because the metal housing was rubbing on the radiator hose muffler hanger, I should have expected that the softer hose would wear away first! I don't think it had been rubbing before, and probably came in contact as things moved around with flying hours, and settled into their final positions.
I am now in desperate need of a Van's 60" Quadrant Cable (A CT Q-60):
http://www.vansaircraft.com/cgi-bin...337-52-285&browse=controls&product=ctq-cables
Does anyone know if these are identical to the 60" A-920 cable from ACS?
http://www.aircraftspruce.com/catalog/appages/a920.php
Of course this happens on a Saturday before a week when I was planning to do some traveling! I will have to call Van's first thing Monday, and am willing to pay overnight shipping (if they will actually be shipping next week), but am wondering if ACS has the same thing, I might have more luck getting them to ship immediately.
Of course, if there is someone in the Houston area who has their FWF kit and has a cable sitting on the shelf that they might not be using for the next week....maybe I offer to have a brand new one shipped directly to them, and I could come get the dusty one off their shelf....Anyone? It's not like I can fly it the way it is, so what the heck am I going to do all day Sunday??!!
Paul
Today, I went to start things up, and it was very stiff to get into full rich for start. I figured it would act like last week, and get better as it warmed up. Instead, when I went to lean, it was essentially locked in the full rich position (if it's going to fail locked, that's a good place to be!). AS it was not a safety issue at this point, and I was only flying across town to an RV Builder's lunch, I continued, leaving it full rich and shutting down with the key. The flight home was uneventful in full rich.
My passenger today was RV-8 builder William Slaughter, and I have to thank him for being interested enough to hang around and help me with the troubleshooting and diagnosis. (Of course, he mentioned something about "honey-doos" needing to be done if he returned home...) We de-cowled, and disconnected the cable at the carb - the carb was free, the cable was not. We cut some cable ties and clamps, and stretch the cable out straight - still extremely stiff from the cockpit control. I have dreaded the thought of taking apart the throttle quadrant, because frankly, once you get it all in place, getting it out can be a real chore - but that was the next step. I got the cable end off of the lever, and the cable was still virtually unmovable - so there was nothing to do but remove it from the aircraft. To make that easier, we took the forward baggage floor out. (Anyone keeping track of how much re-assembly I have to do....?)
Taking the top off of the throttle quadrant, I was able to get a stubby wrench on to the nuts that held the cable housing to the quadrant bracket, and with some not-do-gently pulling from the front, the cable was out - about an hour from the start of disassembly. The cable is essentially frozen in the sleeve, and it appears to be from a spot where the cable had been riding on the muffler hanger (the piece of radiator hose). It had worn through the plastic jacket of the mixture cable, and started to wear away the metal housing. I have not dissected it yet, but I suspect that the cable was crushed in some way, and has damaged the core.
The lesson here is that just because the metal housing was rubbing on the radiator hose muffler hanger, I should have expected that the softer hose would wear away first! I don't think it had been rubbing before, and probably came in contact as things moved around with flying hours, and settled into their final positions.
I am now in desperate need of a Van's 60" Quadrant Cable (A CT Q-60):
http://www.vansaircraft.com/cgi-bin...337-52-285&browse=controls&product=ctq-cables
Does anyone know if these are identical to the 60" A-920 cable from ACS?
http://www.aircraftspruce.com/catalog/appages/a920.php
Of course this happens on a Saturday before a week when I was planning to do some traveling! I will have to call Van's first thing Monday, and am willing to pay overnight shipping (if they will actually be shipping next week), but am wondering if ACS has the same thing, I might have more luck getting them to ship immediately.
Of course, if there is someone in the Houston area who has their FWF kit and has a cable sitting on the shelf that they might not be using for the next week....maybe I offer to have a brand new one shipped directly to them, and I could come get the dusty one off their shelf....Anyone? It's not like I can fly it the way it is, so what the heck am I going to do all day Sunday??!!
Paul