A new inventory model for aircraft spares

A special inventory problem is presented: aircraft spares that are repaired and returned to spares, called rotable inventory. Rotable inventory is not consumed so does not change in the medium term, but is rotated through operational, maintenance and stock phases. The objective for inventory performance is fleet Service Level (SL), which effects aircraft dispatch performance. A model is proposed where the fleet SL drives combined stock levels such that cost is optimized. By holding greater numbers of lower-cost items and holding lower levels of more expensive items, it is possible to achieve substantial cost savings while maintaining performance. This approach is shown to be an advance over the current literature and is tested with case data, with conclusive results.

High performance liquid-level sensor based on mPOFBG for aircraft applications

A high performance liquid-level sensor based on microstructured polymer optical fiber Bragg grating (mPOFBG) array sensors is reported in detail. The sensor sensitivity is found to be 98pm/cm of liquid, enhanced by more than a factor of 9 compared to a reported silica fiber-based sensor.

Fuel level sensor based on polymer optical fiber Bragg gratings for aircraft applications

Safety in civil aviation is increasingly important due to the increase in flight routes and their more challenging nature. Like other important systems in aircraft, fuel level monitoring is always a technical challenge. The most frequently used level sensors in aircraft fuel systems are based on capacitive, ultrasonic and electric techniques, however they suffer from intrinsic safety concerns in explosive environments combined with issues relating to reliability and maintainability. In the last few years, optical fiber liquid level sensors (OFLLSs) have been reported to be safe and reliable and present many advantages for aircraft fuel measurement. Different OFLLSs have been developed, such as the pressure type, float type, optical radar type, TIR type and side-leaking type. Amongst these, many types of OFLLSs based on fiber gratings have been demonstrated. However, these sensors have not been commercialized because they exhibit some drawbacks: low sensitivity, limited range, long-term instability, or limited resolution. In addition, any sensors that involve direct interaction of the optical field with the fuel (either by launching light into the fuel tank or via the evanescent field of a fiber-guided mode) must be able to cope with the potential build up of contamination-often bacterial-on the optical surface. In this paper, a fuel level sensor based on microstructured polymer optical fiber Bragg gratings (mPOFBGs), including poly (methyl methacrylate) (PMMA) and TOPAS fibers, embedded in diaphragms is investigated in detail. The mPOFBGs are embedded in two different types of diaphragms and their performance is investigated with aviation fuel for the first time, in contrast to our previous works, where water was used. Our new system exhibits a high performance when compared with other previously published in the literature, making it a potentially useful tool for aircraft fuel monitoring.

Encouraging student to reflect on their employment experience

The purpose behind this case study is to share with a wider audience of placement officers, tutors and those who are involved in the management of placement students or employment of graduates, the approach taken to encourage reflective learning in undergraduate placement students at Aston Business School. Reflective learning forms an important foundation of the placement year at Aston Business School, where a professional placement is a mandatory element of the four year degree, for all Home/EU students (optional for International students) who are taking a Single Honours degree (i.e. a fully business programme). The placement year is not compulsory for those students taking a Combined Honours degree (i.e. a degree where two unrelated subjects are studied), although approximately 50% of those students taking an Aston Business School subject opt to take a placement year. Students spend their year out undertaking a ‘proper’ job within a company or public sector organisation. They are normally paid a reasonable salary for their work (in 2004/5 the average advertised salary was £13,700 per annum). The placement year is assessed, carrying credits which amount to a contribution of 10% towards the students’ final degree. The assessment methods used require the students to submit an academic essay relating theory to practice, a factual report about the company which can be of use to future students, and a log book, the latter being the reflective piece of work. Encouragement to reflect on the placement year has always been an important feature of Aston Business School’s approach to learning. More recently, however, feedback from employers indicated that, although our students have excellent employability skills, “they do not think about them” (Aston Business School Advisory Panel, 2001). We, therefore, began some activities which would encourage students to go beyond the mere acquisition of skills and knowledge. This work became the basis of a programme of introductions to reflective learning, mentoring and awareness of different learning styles written up in Higson and Jones (2002). The idea was to get students used to the idea of reflection on their experiences well before they entered the placement year.

IT support for managing aircraft spares in a closed-loop supply chain

This paper reports on the development of elements of an e-supply chain management system for managing maintenance, repair and overhaul (MRO) relationships in the aerospace industry. A standard systems development methodology has been followed to produce a process model (i.e. the AMSCR model); an information model (i.e. business rules) and a computerised information management capability (i.e. automated optimisation). The proof of concept for this web-based MRO supply chain system has been established through the collaboration with a sample of the different types of supply chain members. The proven benefit is a reduction in the stock-holding costs for the whole supply chain whilst also minimising non-flying time of the aircraft that the supply chain supports. This type of system is now vital in an industry that has continuously decreasing profit margins, which in turn means pressure to reduce servicing times and increase the interval between maintenance actions.