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Feb
04
2019

Maintenance Minute - SCREWED

Posted 14 days ago ago by jhadmin


SCREWED!


Stuck screws. What a pain! But before you drill the screw head off, here are a few tips to try.


This is mainly for Phillips style screws, but can be adapted to other types.


First, clean out the “cross” recess area. Use an awl or pick if necessary. Any debris like paint, dirt, or rust will prevent the driver tip from fully seating into the cross. If the tip is not seated correctly, it will damage the recess drive areas on the first attempt. If the screw is buried under a layer of paint, remove the paint from the entire screw head area.


Be sure to select the correct driver bit or screwdriver. A Reed & Prince #2 bit will strip out a Phillips #2 screw head and vice versa. Ensure the bit or driver tip is not worn smooth. If possible, use bits with serrations on the drive flanges.


On stubborn screws, use a speed wrench to gain torque and control. Try tightening the screw a tad before loosening. For those who use electric drivers, be sure to select the “drive” speed versus the “drill” speed. You gain a greater torque rating at the bit.


If it’s still stuck, try one of the commercially available screw removers. These are different than screw extractors. Some fit on a rivet gun, while others use mechanical advantage.


When the above methods fail, the next step involves physically altering the screw head itself. On dome/pan head screws, you can cut a single slot and try a flat tip screwdriver. In other cases, you might be able to get a small chisel to bite the edge and tap the screw loose with a hammer.


A step further brings us to Easy-Outs and other similar extractor tools. Since each type works a little differently, be sure to follow the instructions.


As a last-ditch option, there is the dreaded “drill-the-head-off” method. This works provided you: use the correct size drill bit, can access the remaining shank and threads, and the screw is not titanium.


One final tip: A little preventative maintenance prior to screw installation may actually reduce or eliminate the need for the above tips. Except in areas of critical torque requirements, a minute dab of anti-seize or grease on the threads and shank will yield better odds on removing hardware without difficulty in the year(s) ahead. Where torques are critical and no lubricant is permitted on the threads, a light coat of grease on the shank and underneath of the head will also increase your odds.


Final tip-part two: Whenever possible, replace screws with bolts. For example, AN3 bolts are structural equivalents to AN525 screws. And the same goes for MS screws and bolts.   


Final tip-part three: If removing and installing titanium screws with an electric driver, you can superheat the screw at drilling speeds. This may seize the fastener in the anchor nut due to the different thermal characteristics between titanium and steel.


About the author: After 32 years maintaining helicopters in various capacities, Scott Skola concluded a full time career with a major operator in 2014. When not pursuing future writing projects, he can still be seen around the flight line providing maintenance oversight, litigation support, and technical research services. He can be contacted at tekaviationllc@gmail.com






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