One of the safest forms of transportation today is air travel. One of the main reasons this method of travel is so safe can be credited to the expertise of
engineers and aircraft mechanics. Another significant factor in making air travel so safe is the reliability of the tools used to make planes efficient
and safe.
One of those tools used in aviation is the high-precision manual torque wrench. These tools are very precise as they are preset for the amount of torque needed for different fasteners. The torque wrench has to be accurate, so when it comes to aircraft, these tools have to be calibrated regularly.
How the Torque Wrench is Used
Aviation fasteners use torque to determine how tight the connection is between the nut and bolt. This information is crucial because the bolted connection is designed to retain its tightness without loosening. To gain this tightness, an amount of tension is placed on the bolt to exceed the anticipated load.
If a connection is over-torqued, the bolt can give out. If the connection does not have enough torque, it will allow movement in the connection which could lead to the displacement of the joint and possible failure. For these reasons, it is extremely important to achieve the correct amount of tightness in a stud, bolt, or nut.
Types of Torque Wrenches
There are two common manual torque tools used in the aviation industry that are highly precise. One of those is the click type which is a hand-held, industrial-strength tool with a knurled handle. This device also has a non-slip grip and a calibrated clutch with a spring-loaded pull-down lock. This wrench unloads once a preset amount of torque is
reached. This type of wrench is also equipped with a spring to prevent slipping once the right amount of torque is achieved.
Another common
wrench in the aviation industry is the dial indicating beam manual. These models of wrenches serve as both a torque fastener as well they are an
indicator with a dial to measure shock-resistant. The dial indicating beam manual wrench provides evidence you can see as to the amount of torque
exertion. Some of these wrenches are more accurate than the click-type wrenches, but overall, both are durable, dependable, and accurate.
How to Achieve the Right Amount of Torque
The wrench is the tool of choice when it comes to aviation fasteners. It is the tool of choice because in aviation it is essential to follow tightness standards. Engineers state we should measure bolt stretch to determine the tightness of a joint. This is accurate, however, there is no way to measure bolt stretch in many cases and there are no proven specifications to use if we could.
The wrench is the proper tool for airplane assembly and maintenance. Torque specifications are typically listed in inch-pounds, but many are calibrated in
foot-pounds, so depending on which size you are using, you will have to convert to the needed calibration.
Depending on the type of wrench you are using the amount of torque is measured in different manners. The beam version relies on the bending of a steel beam to determine the torque. With the beam model, there is a pointer to show torque on a fixed scale. The scale is attached to the beam close to the handle.
The clicking wrench is used by setting it to a specified torque and using it as a normal ratchet until you hear the handle click. The right amount of torque has then been applied. This wrench version is more expensive than the beam type and will need annual calibration but can be used in almost any position.
Premium tool makers create wrenches with open-end attachments. These attachments work well for things such as prop bolts. Sometimes you can find a
good used wrench for a reasonable price, but if working on aircraft, you don’t want to make sure you are not compromising quality.
Sources:
Types of Torque Wrenches Used in Aviation (May 27, 2020) Maxpro Corp
Torque Wrench Basics (May 12, 2020) Dave Prizio Kitplanes
