Sierra Del Barón Rojo

VH-UMS flew to YRID for maintenance.

I flew out in the previous afternoon instead of the morning of the 12 May because I predicted fog, and just as well, because Friday morning was fog bound.

The trip down was VFR on top until the holes in the cloud layer changed from Few to Scattered. I decended through a big hole and remained clear of cloud at 3000' AMSL from South of Albury right through to Melbourne. Having to fly clear of cloud has happened to me recently on 3 occassions either going to, or leaving Melbourne. Before then I have never had any long flights clear of cloud.

The maintenance went well, I identified several items I wanted repaired and we repaired those as well as perform the regular maintenance and the mandatory Aviation Directive (AD) inspections. I assisted with the compression testing, and magneto re-timing, cleaned the spark-plugs, removed the excess lead build up, lubricated the landing gear and all the bushes and control circuit hinges. We removed the 2nd row seats and removed the floor boards and the flap-motor access plate to identify and rectify the chattering that occurs in the flap while deploying it when the propeller is not spinning and loading it. The chattering was caused by the left-hand flap torque tube binding in the bush which is in a rib near the wing root, suitable lubrication saw this rectified.

I also noticed a squeak when you pull the elevator right back, which we identified as a cable pulley not turning, and we lubricated that pulley's bushing to rectifiy that noise as well.

All up there are many lubrication points that needed to be lubricated and after the control circuits were done the machine feels better to fly and the ailerons feel much lighter to the touch.

We also checked the gear-retraction and verified that there was 1/2 an inch clearance between the tyre and the wheel-well housing. The ASI indication and the gear interlocks when the aircraft is below takeoff speed.

I found that the throttle cable was loose because it was missing a nut on the screw which holds the cable clamp to a bracket on the bottom of the engine casing, infact the casing bracket was loose too, there were meant to be two screws in the bracket but only one remained so even the bracket was loose. Those IO360s sure vibrate. The missing screw was replaced and a Nylock nut was used to fasten the cable clamp.

During this process we identified that the articulating sleeve that the throttle passes through was bent, and the bent section was catching a bracket. This sleeve protects and guides the inner part of throttle cable which is connected to a lever on the throttle butterfly valve. The sleeve can also rotate around its long axis - must have a ball and socket joint on the end - and during this rotation the bend would catch on the bracket and cause the throttle to stick. The clearance of this sleeve is very minimal between the engine casing and the landing gear steering ring support bracket depending on how much throttle is engaged.



The bent sleeve can be seen in the photo, along with the cable clamp that needs to be set at a slight upwards incline, and the steering ring, and the bracket, as well as the throttle leaver in the idle position.

This sleeve has been straighted and the cable clamp is now set on an angle so it is inclined with the sleve when full throttle is selected. The interior of the throttle cable and sleeve has been lubricated with Slick 50 One Lube, which is wonderful stuff; we used it to lubricate all the difficult-to-get-to bushes.

I was so impressed with this lubricant that I have purchased my own can which I can use for lubrication between my regular maintenance intervals. I have extrapolated that I am flying UMS about 180 hours a year, which is a fair bit of flying, and I land on grass and dirt strips, so keeping parts clean and then lubricating them is probably a good idea.