Electronic Bolt Tensioning Equipment

August 19, 2020

A large European aircraft manufacturer was reviewing its use of electronic bolt tensioning equipment (DC tooling) for the future attachment of Engine support (APU) brackets to the wings of its aircraft.

Although electronic bolt tensioning equipment had been used for smaller operations in the past, the ergonomics of lifting and resisting the applied torque (torque reaction) on this size of bolt had prevented their use for this application.

Background

With a supplier chosen for the DC tooling, the customer needed a means of getting the equipment into the position under the wing and of holding the APU bracket in order to fix it in position.

Knowing Androns strength in rigorous design of innovative lifting equipment and its previous track record in supplying electronic bolt tensioning equipment solutions, the customer and the  DC tooling supplier approached Andron for a solution which became the torque reaction trolley.

The Technical Challenge

Although there were many smaller challenges to overcome in the design of the machine, those that drove the main features of the torque reaction trolley are outlined here:

– The machine is trolley-based to enable its deployment and removal from the factory floor.

– The torque reaction trolley has a floor-datum system to lock to features in the floor to enable accurate alignment with the bolt holes in the underside of the wing.

РThe raising and lowering of the DC tooling head is electronically controlled  and pneumatically powered, driving up to meet the wing at the required compound angle.

Due to budget constraints, there were to be only 3 DC tools to complete the tightening of the 6 bolts. The solution developed was a 180 degree index to enable the 3 sets of bolts to be tightened independently.

A further support cradle was integrated to enable the APU bracket to be pre-loaded with the bolts at floor level before being lifted up to the wing underside.

The Andron Solution

The function of the machine was driven by Andron with full consultation with the customers internal ergonomics, safety and production representatives.

A strict risk-assessment process was followed in the development of the machine and all key safety-critical movements were interlocked to ensure a safe operating procedure.

Andron have gone on to create test-coupons and a test-jig for the tightening sequence, replicating aircraft parts to enable the customer a full validation of the equipment for their program.