A large corporate aircraft maintenance company based in Lincoln, Nebraska with a major repair facility in Battle Creek Michigan contacted Sigma to design and build specialty tooling to bore landing gear trunion bearing mounts on a Gulf Stream jet. Periodically, the landing gear trunion bearings must be replaced and the bores machined to remove corrosion. It was discovered that Gulf Stream no longer provided this service in the field, so we were contacted to help with this problem. We presented a proposal to design and build a hydraulic clamp with an intrigal centering device and an air-driven positive feed boring head that attaches directly to the clamp. The tool is capable of producing bores with a concentricity tolerance of +/- 0.001", a bore size to +/- 0.0005", and a surface finish of RA 20. This eliminated the costly requirement of taking the plane to Gulfstream for landing gear work. Sigma also built a clamp for the horizontal stabilizer that uses the same power drive tool. This clamping system was also adapted for use on the horizontal stabilizer spherical bearings.

Another boring tool, designed and manufactured by Sigma, allowed our customer to machine bearing bores in the horizontal stabilizer without removing the fitting. This saved them considerable expense and reduced downtime for their customer.