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This page includes a list of the support FAQ's (Frequently Asked Questions) for each of the Murphy products. Some are quite limited in scope, but by sending questions that you feel may apply, you can help to build this resource. To submit a question, send e-mail to murtech@murphyair.com
Q. Installing leading edge skins on the wings.
A. The leading edge skins are first cleco'd in the top hole on the leading edge rib with the skin hanging down over the table. You pull the skin down and drill the next hole and cleco. You continue doing this until one side is finished. You then remove all the clecos and turn the wing over and repeat the process on the opposite side. Once finished you can remove the clecos and starting at the top of the rib work your way down to the bottom clecoing as you go.
Q. How to deal with proseal?
A. We have found that if you keep your work area clean and uncluttered while working with Proseal eliminates 90% of the common complaints. Small throw away brushes with the bristles cut back to 3/8" work well for applying the sealant. One brush will do about 40" of rivet line before it becomes unusable. Clean excess sealant from visible surfaces before it sets.
Q. Where should I install my air speed indicator static source
A. A perfect spot to get the ambient pressure for the ASI has proved to be the forward cabin side skin (just ahead of the door) on both sides of the aircraft.
Q. What are some common bolt torque values?
A. Quite a few of our builders have been over tightening their bolts. The common bolts are AN3, AN4, AN5 and AN6. The following are torque values in INCH POUNDS using standard fiber nuts. AN3 20-25 AN4 50-70 AN5 100-140 AN6 160-190
Q. How should I deal with areas of the skins were the called out rivet seems to be to short?
A. In our aircraft kits we try to call out the rivet lengths in all the areas of the aircraft. Sometimes, due to varying thickness of material and use of chromate or proseal the rivet length used in the adjacent area may be too short. This is common in the wing area where there are many thickness of material in the spar. If you feel that a certain rivet is too short to be pulled go to the next size rivet.
Q. What is the best way to run the trim tab electrical cables through the elevator.
A. The best way is to run the wires straight up from the trim tab, through a 3/8" hole drilled in the web of the elevator spar and back along the leading edge side of the spar to the center of the elevator and exit out at the center. Also, leave a fair amount of excess cable where the cable exits the elevator or use a quick connect in order to facilitate easier removal and installation of the elevator.
Q. When the floats are installed, the gross weight of the aircraft increases to 1730 lb., is this correct?
A. Yes, we have made provisions in our design to accept the increase in gross weight. One should note that with floats installed, a natural decrease in performance of the overall airframe/engine combination should be expected.
Q. Where is the best location for the brake reservoir?
A. At the top of the firewall, engine side of the firewall.
Q. Where is the best location to ground the battery to?
A. The best location would be to ground the battery to the nearest bulkhead.
Q. Can I add lubrication to the delrin bearing?
A. No, the Delrin is a self lubricating type material. Any lubrication such as WD-40 can dry out the delrin.
Q. I am fighting cooling problems with the engine, what can be done?
A. Increase the cowl exit area. A typical rule of thumb is exit are is 1.5 times the inlet area. If cooling still is difficult sometimes the addition of a lip (flange) about 1 1/2" down on the back of the lower side of the cowling can help create a low pressure area which will improve the scavenging of the hot air out of the cowling. This will draw more air through the engine compartment. Also, the baffle should be place tight against the rear cylinder, this will force the air to travel through the cylinders. Also, you may wish to check the size of your oil fittings on your cooler. Some of the earlier kits were fitted with 3/8" fittings and adapters, these could be increased in size to 1/2".
Q. Can an amateur cover the aircraft?
A. Many builders tend to worry when it comes to covering with fabric. This is an extremely simple process. If you follow the instructions carefully you will end up with a professionally looking covering job. The modern materials available today are designed for ease of use and long life. The most important part of covering is for the builder to have patience, the work, although not complicated, is repetitive.
What about fabric covering for the wing?
A. There is no section in the manual in regard to fabric covering of the wing. the fabric covering method is described in the aileron section. With the wing, Poly-Fiber recommends that the owner use 1 1/2 inch rivet spacing for fabric rivets, if the 3M weather-strip tape (polybond) is not being used. If an owner is using the 3M tape, then a 3 in spacing or less could be used. Also, acid etch prime the metal surface for better adhesion of the polytack.
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