Open manuals (aircraft alterations and repair) to page 7-9

WHAT ABOUT TORQUING??

An early version of torque you may have been exposed to at an early age was ??????????????? An Indian burn

-as an aircraft increases in speed so does the stress on the structure -when engineering firms design a new aircraft they use the information on torqueing to pick the materials that will be used in its assembly -so in using proper torqueing technics this will allow the structure to have its designed strength and reduce the possibility of failure

-Torque also provides for a proper crush on a gasket to provide for the most optimum sealing -By using the torqueing charts in the general hand book on page 134 or amounts specified by the manufacturer this will distribute the loads an aircraft experiences evenly -Without the proper torque the hardware could become loose and back off with minor or major consequences

-The technician is required by law to use the manufactures specification in the course of doing maintenance on an aircraft. If there is a crash and it can be proved that a technician did not use a torque wrench he or she is liable - Click to see web site for definition of torque

torque -The force applied to a lever, multiplied by it's distance from the levers fulcrum is torque the measurement unit for torque is either foot /lbs or newton /meters Torque equals force times distance or T = F x D

Click A one foot bar with 200lbs of weight on it has the same torque as a two foot bar with 100lbs of weight on it

On the Pw100 engine the High pressure disk which collects the energy produced by the compressors and combustion area is held on with 5 (or 6 ) special bolts. These are removed and discarded everytime the disk is removed because they can stretch and become weak after one use. A bolt is worth $ each times 5 bolts = $875 WOW !!!!!!!!!!!!!!!!!!!!!!!!!!!

Types of wrenches 1. flexible beam and rigid frame both use a dial and gauge to read the torque visually. A handle extention will effect the final reading 2. the ratcheting type (or click type) uses an adjustable scale on the handle which the user will set by unlocking the grip and setting to what they wish it to be and relock it. A handel extention will not effect this type of wrench because it is set inside the wrench

3. on a click type wrench you should feel the wrench give a little or click. This shows you have reached the desired or selected torque 4. always return a click type torque wrench back to a zero setting when finished. Never leave a load on it as this will effect the accuracy of the tool 5. If a tool is dropped ALWAYS tells omeone and get it checked for accuracy

TORQUING TEHNIQUE always torque the nut not the bolt. We all know that you only turn the nut and hold the bolt, right?. Anytime the bolt is turned and the nut held, the torque applied will be incorrect. The drag of the bolt in the hole will contaminate your reading, making it read okay when the actual torque is too low. First, make sure the threads of the fastener and the mating hole are clean and free of rust, dirt, carbon and goop. Debris in the hole or on the threads will cause galling of the threads and give an inaccurate torque reading. use washers to spread the load and prevent galling. If the metal you are torquing the bolts into is soft without washers it could be marked up and effect the final torque value

always pull the wrench in a smooth motion never fast or jerky as this will result in an improper torqued unit some books and technicians will say to torque, loosen, and retorque as the first time should set the items together and may not be a true picture of the torque you tried to apply if you are using a tab washer or cotter pin you can go up usually to make so the tabs are on a flat and not a corner and the cotter pin can make it through a hole Click-movie

In aviation you also use a pick if the tab washer is moving around to hold it from moving. When using a torquing sequence continue doing it until the nuts or bolts do not move anymore never dial down to a torque always dial up. Eg if the tool is set to 50ft/lb and you want 40. You must go down to 30 then up to 40 ft/lbs. ATI has put in calibration centres all over the shop and all wrenches must be checked prior to use Class to or 3 inspector must check the wrench for proper setting and stamp off paper work May hear about a dry torque or wet torque which refers to lubricating the bolt prior to torqueing it

THE END