Search Results

In aircraft assembly, a burr left at the interface of any joint is considered a source of potential fatigue life degradation. Burrs can act as an additional stress concentration, leading to fretting, inducing failures. It could also open moisture paths resulting in corrosion. Burrs can affect the fatigue life of various structures differently depending on the type of joint, material, fastener, and installation process. Traditionally, we have disassemled and deburred the interface with various tools such as sand paper, file, chamfer tool, hook, or other tools. Disassembly and deburring of airplane major parts are time consuming and costly. In addition achieving “one up assembly” is not viable unless interfacial burr can be eliminated or reduced to the point where it will not affect fatigue life. In this investigation, the possibility of “one up assembly” via creation of concentric and adjacent clamping in various materials is studied.

Radio Technology Commission for Aeronautics (RTCA) at the request of the Federal Aviation Administration (FAA) formed a committee to prepare a Minimum Operating Performance Standard (MOPS) for aircraft batteries. The MOPS was limited to rechargeable and starting batteries as power sources for equipment installed in aircraft. This committee has being working for the last 3 years and completed the final draft during their 6th meeting in April 2004. The MOPS, to be used by the FAA as the base for a Technical Standard Order (TSO) in preparation, includes the testing and evaluation criteria required for secondary Lead-Acid (Pb-A) and Nickel-Cadmium (Ni-Cd) batteries airworthiness demonstration.

This paper discusses fabrication results experienced with HY-140 steel flight type pressure vessels. HY-140 steel is a recently developed quenched and tempered alloy (5Ni-CR-Mo-V) structural steel with a yield strength of 140,000 psi. Fabrication techniques applied, the tooling used, and the problems encountered are described in detail.