The lock bolt
There are grooves in the lock bolt locking pin post that are cut off to or wrapped around the rod. The lock nut has no grooves, but when it is forcibly screwed onto the pin post, part of the pin post will fall off during assembly. The force (torque) is controlled during installation.
The lock bolts used on the composite material are protected by a special material.To prevent corrosion, the locking nut is not made of aluminum alloy, and to reduce contact stress, a flange is installed on the composite material.The part that falls off when it is installed on the pin post is also designed to reduce contact stress.
Lock bolts are fast and easy to install, but require wide access to parts, and other forms of fasteners are required when access is difficult.
HI-LOK bolt
The hi-lok bolt has a linear thread.Its locking nuts also have linear threads.The mounting pressure is controlled by the groove of the locking nut, which is cut off by the screw locking mechanism during installation.
In the application of composite material, it is similar to the lock bolt with protection. The lock nut is not made of aluminum alloy. To reduce contact stress, a flange is installed on the composite material.
Specific power tools need to be used for hi-lok bolt installation, and hex keys and standard wrenches can also be used for manual installation.
Eddie bolt
The stud of the Eddie bolt is also threaded by a thread.Part of the thread of its bolt is machined to form three grooves.When the lock nut is installed, the circular protruding part of the lock nut is screwed into the groove. The rotary die provides mechanical locking and controls the torque of the lock nut.
Because it was originally designed for composite applications, the design features are similar to those of lock bolts and hi-lok bolts.There is no debris falling off when it is installed, thus reducing the amount of debris that needs to be removed after installation.The mounting torque of this bolt is more reliable than that of other bolts.
For these reasons, Eddie bolts are widely used in composite assembly and hi-lok bolts may be replaced for maintenance purposes.Special power and hand tools are used to install it.
Except for a special guide screw housing, the other ones are basically the same as the hi-lok bolts.Hex keys and special guide bolts can also be used for manual installation.
Composite components such as close to cover plate and belly fairing must be removed during routine maintenance.These parts need to use light weight, good corrosion resistance removable titanium alloy protruding head and countersunk bolt.These fasteners are all standard.
Since the installation torque is controlled by the worker, the requirements of BAC 5063-4 must be observed during installation.Gaskets can be used on bolt heads and nut heads to reduce contact stress and to ensure electrical and lightning strikes and electrostatic contact. These gaskets can be reused.
The locking mechanism of these fasteners must be replaced after repeated assembly and wear.Make sure the fasteners in the replacement area are the same as or can be replaced, and that the fasteners are electrically compatible with the carbon fiber parts they come into contact with.
In the bolt assembly, a lot of times are restricted by conditions, can not be close to both sides, this time need to use blind bolt to install.
Special blind bolts are used for assembly of composite materials such as elevators, rudders and other inaccessible areas.Blind bolts are also used in the 777 tail and 787 extensive structural repairs.
Since blind bolts are used for hard-to-reach distal ends, the forming head is difficult or even impossible to inspect, so the BAC 5063 installation procedure must be strictly followed.