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In a letter to the Federal Aviation Administration, the National Transportation Safety Board expressed its concern about multiple tyre failures in wide‐bodied aircraft, such as that experienced by the Continental Air Lines DC‐10 at Los Angeles International Airport on March 1st, 1978. Several actions the FAA had underway or was planning to initiate. The Safety Board acknowledges these actions as a step toward reducing the potential risk of tyre failures. However, the Safety Board's public hearing, which was convened on May 30th, 1978, as part of the investigation of the DC‐10 accident, elicited much testimony regarding factors which can affect tyre safety and reliability; and as a result, we believe that additional regulatory or advisory actions are needed in the areas of design standards, qualification testing, quality control during manufacture, and operational limits. Our concerns apply to retreaded tyres as well as new tyres.

This case seeks to illustrate the specific problem of excessive defects in radial tyres produced in a renowned tyre manufacturing company in India. This paper aims to show how lean Six‐Sigma methodology can be used to tackle the specific issues like defects reduction.

The management took this problem on top priority as it is eroding their brand value and financial performance. A Mumbai‐based lean Six‐Sigma consulting group was approached to tackle the issue. One of the authors, who is pursuing research on determinants of successful lean manufacturing implementation in Indian industries, joined this project as a part of his field study and he spent considerable time in discussing and observing the issue with people of different hierarchical levels of the company. Lean Six‐Sigma methodologies were incorporated and the problem was evaluated with root‐cause analysis. This case is formulated on the basis of the initial findings of the study in an Indian tyre manufacturing organisation keeping the actual name of the company in disguise.

On the basis root‐cause analysis of the radial tyre manufacturing process, it was found that presence of foreign particles in the manufacturing environment, under‐ageing and over‐ageing of tyre components, and inefficient bead winding process, were the main culprits of defects. It was confirmed that lean Six‐Sigma methodology can serve as a major tool to reduce defects in the tyre manufacturing process in India.

This paper provides some key insights to the successful adoption of lean Six‐Sigma tools in an Indian industrial environment, where lean practices are still in the very nascent stage and very little literature is available in this context.

A FEW brief words on the Total Quality Control concept where in embraced the whole brief of the Quality Engineer — the field of design (conformance with constructor's requirements), manufacture (conformance with specifications) and reliability (conformance with users' requirements). Ideally the Quality Engineer will liaise with both Sales and Design engineers to achieve complete drawing board conformance with customer requirements at the design stage and it is at this stage where, of course, a designer needs to know exactly what is wanted of him. More important, he needs room for manoeuvre, for alternative proposals. As far as concerns aircraft, it is not so long since the tyre designers used to be faced with the appalling difficulty of being presented with a hole of very limited dimensions in each wheel bay into which he had to fit a tyre or tyres come what may. Apart from the limited dimensions of the hole, its dimensions were usually by this time inviolable. If we were lucky we would have some idea of the aircraft take‐off and landing weights and speeds, essential parameters with which the tyre designer commences his calculations.

IT is one of the hard facts of life that tyres tend to skid more readily under wet road or runway conditions — this is a most unsatisfactory basic situation and merits the greatest possible effort to make a substantial improvement. The problem has been studied basically by various bodies including N.A.S.A.

The first touchdown moment of aircraft tyres on a runway is the critical phase where maximum of the vertical and horizontal ground loads is produced. Some valuable drop tests have been performed at Langley research centre to simulate the touchdown and the spin-up dynamics. However, a long impact basin and a huge power source to accelerate and decelerate the landing gear mechanism have been used. Based on a centrifugal mechanism, the purpose of this paper is to propose the conceptual design of a new experimental setup to simulate the spin-up dynamics.

A schematic view of the proposed mechanism is presented, and its components are introduced. Operating condition of the system and the test procedure are discussed in detail. Finally, tyre spin-up dynamics of Boeing 747 is considered as a case study, and operating condition of the system and the related test parameters are extracted.

It is shown that the aircraft tyre spin-up dynamics can be simulated in a limited laboratory space with low energy consumption. The proposed setup enables the approach velocity, sink rate and vertical ground load to be adjusted by low power actuators. Hence, the proposed mechanism can be used to simulate the tyre spin-up dynamics of different types of aircraft.

It is important to note that more details of the setup, including the braking and actuating mechanisms together with their control procedures, should be clarified in practice. In addition, the curved path introduced as the runway will cause errors in the results. Hence, a compromise should be made between the tyre pressure, path curvature, the induced error and the cost of the experimental setup.

The proposed experimental setup could be constructed in a limited space and at a relatively low cost. Low power actuators are used in the proposed system. Hence, in addition to the performance tests, fatigue tests of the landing gear mechanism will also be possible.

Based on a centrifugal mechanism, the conceptual design of a new experimental setup is presented for simulating the tyre spin-up dynamics of aircraft. Considering that the drag load developed during tyre spin-up following initial touchdown is an important factor governing the design of the landing gear mechanism and aircraft structure, the authors hope this paper encourages engineers to continuously make efforts to increase the transparency of the touchdown process, enabling optimisation of landing gear design.

The aircraft’s tyres are forced to spin up at touchdown. A considerable amount of frictional energy will be converted into heat, raising the tread temperature and leading to thermal wear. This study aims to develop a model to analyse the tread heat and discuss the effectiveness of two wear reduction methods.

The tread temperature is calculated using Laplace’s Equation. The efficiency of pre-rotation and soft landing in reducing tyre heat is studied using a developed three-dimensional heatmap method.

The result indicates that pre-rotation can significantly lower landing gear’s heat generation at touchdown. The soft landing, instead, has an insignificant or counterproductive effect.

The pre-rotation can significantly increase the tyre’s lifespan and cut the replacement cost. The emission of tyre particles into the environment can be reduced to protect the planet and human health.

Few studies have used a theoretical model to estimate the tread temperature. The existing studies have only dealt with the maximum tread temperature or the tread centreline temperature, which is insufficient to discuss the heat across the entire tread. However, the heatmap method in this paper can do the job.

Since the 1950's the radial ply tyre has gradually penetrated all fields of ground transportation to the situation today where it enjoys a dominant position, particularly in the Western World where road surfaces are of a high standard. The advantages offered by the radial ply construction for passenger car and road vehicle applications are well known, although their lack of robustness has prevented their more general adoption in areas where roads are of an inadequate standard.

Due to the static condition of the wheels at touchdown, they skid on the runway, which may cause the tyres to burn and wear. This phenomenon occurs in a fraction of a second, known as the spin-up period. The purpose of this paper is to introduce a new strategy to reduce the horizontal force, tyre temperature and wear during the spin-up period.

First, the dynamics of two different phases of landing, namely, spin-up and breaking phases, are reviewed. Second, a strategy to prevent excessive temperature and wear of the tyre is presented.

It is found that using a lubricant and coolant, such as water, at the spin-up stretch of the runway is a simple and practical solution to prevent excessive temperature and wear of the tyre. It is revealed that, despite increasing the spin-up period, the rise of the tyre temperature is eliminated and the material properties are preserved for effective braking. A rough quantitative analysis demonstrates that the wetting of tyres in the spin-up phase decreases the loads and tyre wear effectively.

Wetting the touchdown region of the runway without significant areas of standing water is the most practical strategy with the technology available today.

A new strategy is presented for landing with reduced tyre wear. It is the hope that this paper can inspire continuous efforts to realize the implementation of the strategy.

NOWHERE IN BRITISH INDUSTRY has Barber's mini‐Budget been greeted with more relief than among tyre manufacturers. For them, the Chancellor's action in cutting purchase tax will not make a new pennorth of difference to the price of their product. And only a tiny fraction are sold on hire purchase.