CRAFTSMAN'S CORNER ENGINE CONTROLS AND RETURN SPRINGS

Submitted by GARRY FANCY EAA 24493

8 Sicard Way Kanata, Ont., K2L 2X6

Canada When starting the engine in my Skybolt after a long storage period and minor overhaul, I could not get the Lycoming HIO-360 engine to run when I advanced the throttle. I assumed the Bendix fuel injector was malfunctioning due to a relatively long period of inactivity, however, after some 20 or 30 attempts to clear it, I gave up and was ready to remove the injector for overhaul. After opening the engine cowling and examining the injector, I noticed that the mixture control was in the halfway position and that the flexible mixture control cable was bowed and not in its original location. I soon realized that the culprit was not the injector, but improper position of the mixture control lever. The solution to this was to more firmly anchor the flexible cable. As an added precaution I attached a small light coil spring (B) to the mixture control lever such that, in the even of failure of the control cable, the spring would move the mixture to the full rich position. Several months later, while attempting to start the O-320 Lycoming in my newly completed Wag Aero "Husky Cuby," a similar situation occurred. The engine would start on prime, but shortly thereafter would stop. Deja vu a check under the cowling revealed the problem. The "bug nut" keeping the mixture control cable attached to the mixture lever had loosened and the mixture lever moved to the "Idle-Cut Off" position. Conversations with sev-

eral pilot acquaintances have revealed that they also have had similar incidents in the past. In this case, I fastened a light spring (B)to pull the mixture lever to the full rich position and, as an added precaution, I also did the same for the throttle control (A). The spring can be hooked to a convenient hole on the throttle arm (generally there are spare holes) and the other end to some convenient location on the powerplant installation roughly in line with the direction of motion. In the case of the mixture lever spring, I made a simple aluminum stand-off bracket. Care should be taken when selecting the spring. If it is too strong, it will overcome system friction and coax the lever to the full rich or full power position. It should be just strong enough to ensure that the lever will move to the full power position in the event of control system loss. An alternative approach to installing one spring to bring the actuating lever to the full power position would be the installation of two springs, working in opposite directions, to bring the lever, in the event of control failure, to a high power setting, but not necessarily the maximum position. If the two spring system is used, even greater care must be exercised in selecting the strength of the spring. This system has a potential for power loss should the "forward" spring fail or become disconnected. It goes without saying that all powerplant controls, particularly flexible cables, should be thoroughly anchored to prevent outer housing moving and disturbing the relationship between the cockpit control levers and the engine (carburetor) control arms. If this does happen, sudden inadvertent engine stoppage may easily occur.

Ben Owen DEBURRING TOOL Dwight F. Giles, Vallejo, CA is the

machinist who makes these handy deburring tools from an old used three corner file. The grinding must be done carefully so as not to remove the temper or hardness. Grinding is done by hand on a 6" grinder. The end of the file is left on until the grinding is almost complete. This gives you something to hold and helps to keep the tip from turning blue. Before the tip of the file is removed it can also be ground and the tool made. A good deburring tool

can also be used as a scraper. Dwight uses his a lot on his lathes as well as on sheet metal.

BULKHEAD FITTING

This bulkhead fitting was also made by Dwight Giles. These fittings have been installed on three aircraft to date... two with 1/32" sheet metal bulkheads and one that is 1/2" wood covered with sheet metal. The aluminum is 2024-T4 but all parts could be aluminum if anodized. For the throttle with the 3/8" sleeve the collet was made large enough for the 3/8" part to fit through the fitting. A split

bushing or sleeve was used to tighten down on the cable body.

Firewall fitting assembly

Firewall fitting disassembled showing slot and aluminum portion. It tightens on the cable through the firewall. 46 JULY 1992