In this paper, we have been trying to find to find a solution to improve the acceptance rate of aircraft mounted accessory gear box main casing Mg alloy (RZ 05) casting for fixed wing military aircraft applications. We have described the functions, features, processing and airworthiness certification details of aircraft mounted accessory gear box casting in detail. The main problems leading to high rejection rate of casting have been brought out using data analysis of the last 6 years manufacturing details. From the analysis, it is found that the integrated as-cast long and curved oil passages in the casting, melting and casting issues of Mg alloys are the principal factors resulting high rejection rate. To improve the acceptance rate and minimize the loss incurred, we propose the following two main solutions based on properties evaluations, yield and cost assessments, (1) the removal of integrated as-cast oil passages from the design and replace them with external oil passage using pipesis expected to improve the acceptance rate to 50%, (2) the change of material from Mg (RZ 05) alloy to Al (A356) alloy is anticipated to enhance the acceptance rate to more than 70%. Further it is also suggested that the incorporation of both solutions in the aircraft mounted accessory gear box casting will significantly benefit the casting acceptance rate, yield rate and most importantly, cost savings.

Al Alloy, Mg Alloy, Sand Casting, Aircraft, Casting Properties, Yield and Cost Assessment