Riveted Joints in Aircraft Manufacture

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Questions and Answers

What happens if a countersinker is set too deep?

The hole is enlarged and the metal will shear across the head (correct)

The hole will be smaller and the metal will be stronger

The rivet will be driven faster

The countersinker will break

Why should you avoid countersinking too far when working with thin material?

The rivet will not be driven properly

The countersinker will break

The riveted joint will be weakened (correct)

The hole will be enlarged and the metal will shear across the head

What is the purpose of supporting the preformed head with a dolly when hand riveting?

To hold the rivet in place

To make the rivet head smaller

To drive the rivet faster

To ensure the sheets are drawn together (correct)

What is the correct sequence to form a reaction head when hand riveting?

Partly form the tail with a flat snap, then finish with a suitably shaped snap Signup and view all the answers

How should the rivet be driven when hand riveting?

Using a hollow set or draw tool Signup and view all the answers

What is the purpose of a draw tool in hand riveting?

To draw the sheets together Signup and view all the answers

What is used to drive aircraft solid rivets in pneumatic rivet guns?

Compressed air Signup and view all the answers

What is the action applied to the rivet snap in pneumatic rivet guns?

A hammering action Signup and view all the answers

What is the main reason why lap joints are not used in high-performance aircraft?

Because they disrupt airflow during flight Signup and view all the answers

What is the purpose of using a doubler in a flush joint?

To tie the skin and an insert together Signup and view all the answers

What type of joint is a combination of flush and lap joints?

Joggle joint Signup and view all the answers

What is the advantage of using flush joints in aircraft manufacturing?

They provide aerodynamic cleanliness Signup and view all the answers

What is the purpose of a lap patch?

To repair a damaged skin Signup and view all the answers

What is the characteristic of a lap joint?

The skins are riveted together with a distinct step or change in levels Signup and view all the answers

What is another use for joggle joints?

To fit doublers over other internal structure Signup and view all the answers

What is the substructure used in flush joints?

Longerons, bulkheads, or formers Signup and view all the answers

What is the primary purpose of deburring holes after drilling?

To achieve a smooth surface finish Signup and view all the answers

What tool can be used as an alternative to a deburring tool if it is not available?

A larger diameter drill bit Signup and view all the answers

What is the primary purpose of a snap in solid riveting?

To form the rivet head Signup and view all the answers

What is the purpose of a dolly in solid riveting?

To support the preformed rivet head Signup and view all the answers

Why is it important to ensure no gaps are present between layers during riveting?

To ensure correct formation of the rivet Signup and view all the answers

What is the purpose of applying sealant during riveting?

To prevent corrosion Signup and view all the answers

What tool is used to draw the metal sheets together during solid riveting?

A set (also known as a draw tool) Signup and view all the answers

What is the primary method of riveting used on aircraft structures?

Reaction riveting using pneumatic riveting guns Signup and view all the answers

What is the advantage of using a C-yoke or alligator-yoke squeezer?

Uniformly sized shop heads and reduced installation time Signup and view all the answers

What is the purpose of the bucking bar?

To form the shop head of the rivet Signup and view all the answers

Why is it important to use the fewest blows possible when forming a rivet?

To avoid cracking the rivet due to work hardening Signup and view all the answers

What is the driving face of the bucking bar machined for?

To smoothly deliver force to the rivet Signup and view all the answers

How is the correct pressure of the rivet gun adjusted?

By actioning the gun against a piece of wood Signup and view all the answers

What is the purpose of holding the bucking bar flat and square against the rivet's tail?

To deliver force evenly to the rivet Signup and view all the answers

What should be done with the rivet gun trigger?

Pull the trigger quickly to form the rivet Signup and view all the answers

What is the purpose of the wood during rivet gun adjustment?

To indent the wood but not shatter it Signup and view all the answers

What could be the cause of a cracked shop head?

Rivet hit too long Signup and view all the answers

What is the purpose of countersinking the skin in NACA riveting?

To allow the rivet to fill the countersink and obtain a flush surface Signup and view all the answers

What tool is used to mill the excess material from the shank in NACA riveting?

Micro-shaver Signup and view all the answers

What is the cause of a burr under the rivet head?

Rivet not deburred correctly Signup and view all the answers

What is used to confirm a gap under the rivet head after installation?

Feeler gauge Signup and view all the answers

Why is the NACA riveting technique used?

To install a rivet with a flush shop head due to interference from adjoining parts Signup and view all the answers

What happens to the rivet after it is installed in NACA riveting?

It is driven to fill the countersink Signup and view all the answers

What is the result of a rivet set that is too big for the rivet?

A skin marked by the rivet set Signup and view all the answers

Study Notes

Riveted Joints

Three types of riveted joints are used in aircraft manufacturing and repair: lap joints, flush joints, and joggle joints.

Lap Joints

In a lap joint, the skins are riveted together, resulting in a distinct step or change in levels.
The skins are not on the same plane, but are stacked.
Lap joints are not suitable for aerodynamic smoothness due to disrupted airflow during flight.
They are generally used on light aircraft where aerodynamic smoothness is not a concern.
Lap patches are an example of where lap joints are used.

Flush Joints

Flush joints are used to obtain aerodynamic cleanliness between two skins.
The skins are riveted to the same substructure, putting them on the same plane.
The substructure can be longerons, bulkheads, formers, etc.
A separate metal piece called a doubler may also be used as the substructure.
Flush patches are an example of a flush joint.

Joggle Joints

A joggle joint is a combination of flush and lap joints.
One skin is joggled to accommodate the other, producing one smooth side.
Joggle joints are also used when fitting doublers over other internal structure.

Deburring

Holes should be deburred after drilling using special deburring tools.
If a deburring tool cannot be sourced, use a larger diameter drill bit to achieve similar results.

Solid Riveting Tools

Solid rivets can be closed by hand using appropriate snaps, sets, and dollies.
A set (also known as a draw tool) is a hollow punch used to draw the metal sheets together and bring the preformed rivet head against the metal surface.
A snap is a form of punch with a recess at one end, the same shape as the rivet preformed head.
A dolly is a metal block with a recess the same shape as the preformed head of the rivet, used to support the preformed rivet head.

Hand Riveting

Hand riveting may be convenient for small jobs or those done away from the aircraft.
When solid rivets are closed with a hand hammer, the preformed head should be supported in a dolly.
A hollow set or draw tool is used to ensure the sheets are drawn together.
The tail is then driven using a flat snap to form a reaction head with a thickness of 0.5D.

Pneumatic Rivet Guns

Aircraft solid rivets are often driven with pneumatic rivet hammers or guns.
Pneumatic rivet guns use compressed air to drive a piston back and forth, applying a hammering action to the rivet snap.
This method offers several advantages, including producing uniformly sized shop heads, reducing installation time, and being suitable for use with two types of guns: C-yoke and alligator yoke.

Bucking Bars (Dollies)

The shop head is formed by the bucking or vibrating action of a bucking bar when the rivet gun is activated.
Bucking bars come in many different sizes and shapes for different applications.
The driving face of the bar is machined smooth and polished so that no marks are left on the rivet tail.

Using the Rivet Gun

Prior to installing rivets, the gun needs to be adjusted for correct pressure/hammer.
This is achieved by actioning the gun against a piece of wood and adjusting the airflow to indent the wood but not shatter it.
Place a rivet in the hole and hold the gun against its head with enough pressure to keep the rivet against the skin.
Hold the bucking bar flat and square against the rivet’s tail and pull the trigger to form the rivet.

Common Riveting Errors

Burr under head: not deburred correctly.
Cut shop head: dolly did not cover entire end of rivet.
Cracked shop head: hard rivet or hit too long.
Skin marked by oversize rivet set: set head is too big for rivet.
Skin marked by rivet set: set not centered on head of rivet.

NACA Riveting

NACA (National Advisory Committee for Aeronautics) flush riveting technique is used to install a rivet with a flush shop head.
The skin is countersunk and the rivet installed from inside the structure.
The rivet is driven to fill the countersink.
A micro-shaver is then used to mill the excess material from the shank and obtain a flush surface.

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Description

Learn about the three types of riveted joints used in aircraft manufacture and repair, including lap joints, flush joints, and joggle joints.