[ published originally in the Plant Engineer , A Journal on Equipment Management – Sep-Oct 1979 edition ] – A publication of The Institution of Plant Engineers , Madras , India
Preventive Maintenance and Its Impact on Equipment Management in the Army
By Major K Hari Kumar and Major PGK Atreya [ Faculty members of EME School ,Baroda]
1. The best and most efficient machine invented so far – the human body – is examined by a doctor while the machine is working. It is done with the aid of reliable and precise instruments and any malfunctioning is diagnosed and any treatment is given in the course of the machine being in operation. When an incurable failure does occur, that particular part is removed or replaced by physical operation, and the entire machine is never dismantled. The emphasis, by necessity, is on Preventive Maintenance. Here, the part played by the owner of the machine is no less important. The machine works longer mainly due to the care and caution exercised by the user.
2. No equipment has yet been designed to function without any maintenance. To perform the tasks better, the Army has become more reliant upon equipment which have become increasingly more complex and sophisticated over the years. Combat readiness Implies both personnel readiness and equipment readiness. Management thus becomes a primordial command function.
3. In the present days’ short and intense wars, maximising the availability of equipment on the hands of the troops is a decisive and vital battle winning factor. For a country like India with a developing economy and limited infrastructure for defence production, it is not feasible to rely purely on timely replacements of war like equipment. Preventive Maintenance, in our context, thus can achieve significant results and can have a great impact on Equipment Management in the Army.
WHAT IS PREVENTIVE MAINTENANCE ?
4. Preventive Maintenance (PM) can be defined as the care and servicing by personnel for the purpose of maintaining equipment and facilities in satisfactory operating condition by providing for systematic inspection, detection, prediction and correction of incipient failures either before they occur or before they develop into major defects.
5. The Army system of maintenance is based on the premise that maintenance problems must be identified and corrected before expensive, time consuming repairs are required. The foundation of the system is therefore preventive maintenance.
6. Some components of any equipment have a shorter service life than the equipment itself. If the system is to effect repair as far as possible, replacement for those short-life components must be available at each category of maintenance. Repair parts must be stocked and ordered based on usage and need at each level. PM thus involves not only inspection but also planned replacements of components and adequate inventory supported by a reliable and sound re-supply organisation.
7. Usually, the more established the technology, the greater is the degree of PM. As the plant acquires new and unusual operating conditions, the percentage of emergency or unforeseen maintenance increases. As Army Equipment are designed to operate in difficult conditions, such maintainability parameters are taken care of right at the development or weapon evaluation stage to minimise their breakdown maintenance in Service.
8. The following points form the basis for determining the degree to which PM should become involved:-
(a) Will the faulty component put the equipment or a portion of the equipment out of service?
(b) Are spares or stand by equipment available?
(c) Is it cheaper to maintain the equipment or to replace it ?
(d) Can the equipment wait for the next normal turn round?
(e) Can the equipmeet be redesigned to extend its run life?
(f) Will the equipment last longer than the system in which it is placed? If so, why not let the equipment run to destruction?
ESSENTIALS OF PREVENTIVE MAINTENANCE
9. The essentials of PM are given below:-
(a) Proper Selection and projection of requirements for equipment – In the Army, this is ensured by the General Staff through the formulation and issue of GSQR (General Staff Qualitative Requirements). The expected performance, service life, conditions of usage, average ability of handling the equipment by the user etc are given out in the GSQR.
(b) Designing equipment for optimum reliability and maintainability based on accepted standards of availability and accepted life cycle cost – The Research and development Organisation undertake the design and they consult the users and the maintenance personnel in ensuring maintainability of components/assemblies/complete equipment itself. Maintainability Advisory Groups of the Corps of Electrical and Mechanical Engineers whose role is to ensure operational fitness of all Army Equipments, are closely and intimately associated with the design and development of any newly introduced equipment in the Army whether it is indigenously manufactured or purchased from abroad.
(c) Evaluation and enforcement of norms for use- All newly introduced equipment are invariably subjected to user cum maintainability trials before acceptance for introduction into service. Based on such trials, norms for usage are issued in the forms of technical instruction which include details for upkeep such as lubrication, cleaning and the like.
(d) Periodic Inspection of equipment to uncover conditions leading to breakdowns or premature down gradation, assess mechanical state and impart classification
Right from the introduction of any equipment, inspections are mandatory till the equipment is phased out of service. These inspections mainly could be divided into :-
(i) Initial Inspection
(ii) Periodic inspection
(iii) Transfer inspections
(iv) Prefiring/After firing inspections in the case of weapons.
(v) Seasonal inspection
(vi) Inspection before and after usage in war.
(vii) Inspection before and after repairs or break-down maintenance.
(viii) Special Inspections on specific order.
(e) Upkeep of equipment by planned replacement of certain components, adjustments and undertaking repairs to minimise wear, prevent breakdown and also to keep the performance at optimum levels- This task is a logical corollary to inspections and is performed by the Corps of Electrical and Mechanical Engineers in the case of almost all the Army Equipments with a few exceptions like the light repairs to signals equipment etc which are done by the users themselves. An efficient and time-tested echelon repair system ensures that repairs are performed as far forward as possible with the minimum possible movement and down time. Whenever equipment is back loaded for extensive repairs/ overhaul, replacements are provided to the user.
(f) Defect reporting. investigations, issue of modifications to equipments, procedure or norms of usage – This aspect is ensured by extensive use or established practices in predictive and corrective Maintenance procedures. Fact finding activities – data studies-help in formulating scheduled maintenance more effectively and to predict deterioration and likely failures. The FORWARD (Feedback of Repair Workshops and Reliability Data) studies conducted by the Corps of Electrical and Mechanical Engineers go a long way in the furtherance of the above objective. They establish frequency of repair pattern, defect and symptom relationship. Defect reporting and subsequent investigations is a continuous process by all concerned right from the introduction of an equipment till It is discarded from service. Suitable modifications to design, procedure for operation or repairs and norms of usage are issued based on the findings of such investigations.
IMPLEMENTATION OF PM
10. Timely checks or inspections and proper documentation are the key points to implement PM. Some of the leading questions are :-
(a) What is the range and depth of the workload?
(b) What are the items to be checked ?
(c) What should be the frequency of checks?
(d) What should be the mode of checking?
(e) What resources are required to perform the checks?
(f) What should be the optimum inventory level ?
(g) What should be the control information required ? –for providing optimum follow up
(h) What is the training required to acquire knowledge and skill with a view to carry out inspection and repairs ?
11. Proper and satisfactory answers to above questions lead us to an effective PM programme.
12. A successful PM programme should include the following :-
(a) Preliminary Planning – Prior to developing a PM programme it is essential to establish an overall plan and to enlist the interest of all concerned, including the user as well as the staff in charge of Military Operations. A successful programme may require from several months to several years to establish. An outline programme of objectives and a definite schedule for evaluating and reporting progress are necessary in the preliminary planning.
(b) PM Organisation and staffing – Personnel must be provided to act up and operate a PM programme. The needs will vary widely with type and size of plant or variety and complexity of equipment and their population in service. Proper and healthy operation-maintenance interface is essential for success. As the Army needs more bayonet strength, the tooth-to-tail ratio acceptable is to be borne in mind while planning the maintenance organisation and its staffing. This calls for the best possible quality input of man power and the most suitable training of the staff to cope up with the workload.
(c) Frequency of PM – There are two general techniques used in the establishment of inspection frequencies. They are general inspection and specialised inspection .General inspection frequencies are developed and used for smaller and simpler equipment/plants because administration is much cheaper. The inspection of the entire equipment or a portion of it is done at one time. The basic equipment along with its accessories are inspected at the same time in accordance with a pre-established inspection checklist. Generally this inspection would be accomplished by one inspector, although he may call in one or more specialists to assist him with certain aspects of the work. Specialised inspection has a higher degree of sophistication than the general inspection procedure. It is used in larger plants or equipment and permits an inspection economy. Parts of the equipment which are longer – lasting need not be inspected as often as parts which fail more frequently. Where there is a large number of equipment under the PM programme as in the Army, considerable savings in inspection time can be affected if the frequencies employed take advantage of the full trouble free operational period of each part of the equipment. For instance control equipment may require inspection every two months. while electric motors for a given piece of equipment might be inspected annually.
(d) Schedules and scheduling -After developing the PM check sheet for each piece of equipment or facility, the next step is to develop the schedule so that the necessary inspection will be performed as needed. The base work load as represented by the maintenance inspection check sheets can be fitted into a schedule which provides a relatively even and steady flow of inspection work throughout the year, taking into account the variations and requirements arising from seasonal, operational and training commitments of the Army. Schedules can be broadly divided into two-namely check schedules and servicing schedules. In both the cases, scheduling depends on :-
(i) Type and terrain of normal usage.
(ii) Conditions affecting adjustments.
(iii) Rate of Wear.
(iv) Conditions leading to damage or deterioration.
(v) Intensity of Usage.
(e) Statistical methods of analysis. – In order to cope up with the increasing complexities of equipment, Army maintenance organisation is becoming more and more dependent on statistical methods of analysis to isolate problem areas in order to devote more and specialised attention to these aspects which increase downtime and non-availability of equipment to the user. Modern operational research techniques are widely employed to determine repair arisings and the quantum of maintenance support required for the same for advance planning. Scientific forecasting and thorough planning are undertaken to meet such situations adequately.
(f) Maintenance Recording-Two types of data are included for recording. They are firstly a permanent physical data concerning the equipment and their installation (a history sheet in certain cases) and secondly a record of repairs and adjustments carried out on it from time to time. Where these records do not exist, they should be developed as the PM programme progresses. It is very important that all significant repairs and adjustments be recorded so that the data can be carefully analysed. Only by knowing what has happened in the past can analysis be made to improve operation and reduce maintenance costs in the future. For a PM programme to operate successfully, a maintenance request or a maintenance work order must be written to cover all repair work. Such documents not only help in improving the maintenance of single equipment but also help in comparative studies to determine short comings both in procedures for usage as well as techniques adopted for maintenance. They also serve to carry out proper loading of maintenance staff and review of PM planning. In the Army, work values have been adopted for each equipment to determine the quantum of repair efforts and therefore maintenance recording is essential to account for the manpower utilised in maintenance activities. Maintenance records are necessary to provide information on equipment status, usage, location, and maintenance performed. The information is used to effect equipment improvement, improve maintenance procedures and provide a basis for procurement.
(g)) Controls-Controls are essential to identify the permissible and optimum level of Maintenance and in determining the level of maintenance actually achieved at any given point of time. Some of the indices that can be adopted are:-
(i) Percentage non-availability of the equipment to the user.
(ii) Maintenance cost per unit of equipment.
(iii) Wastage data of spares and expendables as percentage of total life cycle cost of equipment.
(h) Maintenance costs and budgeting-The most effective way to budget maintenance for any equipment is to start with the determination of the extent of the maintenance requirements and then proceed to develop the necessary cost of the maintenance service centres which group together related repair and technical functions. Some of the methods of costing maintenance are:-
(1) Rate of maintenance cost to value of facility.
(ii) Ratio of maintenance cost per unit.
(iii) Maintenance labour costs compared with maintenance material costs.
(iv) Maintenance cost per unit of operation (usage of equipment)
(v) Number of maintenance men compared with number of users.
(vi) Maintenance hours per unit of usage .
BENEFITS OF PM IN THE ARMY
13. If the PM programme is properly conceived and implemented and if proper controls exist, it is difficult to imagine a situation where no economic benefit would result. Undoubtedly, the major objective when installing a PM programme is reduced cost, however, the reduction in cost may come about in several different ways as under:-
(a) Reduction in overall maintenance costs.
(b) Reduced downtime resulting from few equipment breakdowns.
(c) Maintenance can be performed when convenient both for the user and the maintenance staff.
(d) Fewer major repairs since major repairs are circumvented by timely routine repairs.
(e) Reduced overtime costs and more economical use of maintenance workers as a result of working on a scheduled basis rather than a crash basis to repair break downs.
(f) Less stand-by and reserve equipment as the cost of the PM could be done on a stream basis.
(g) Minimum spare parts inventory.
(h) Increased reliability.
(i) Better conservation of assets and enhanced life expectancy, as a result of eliminating premature replacement of machinery and equipment
(k) Identification of equipment with excessive maintenance costs indicating the need for corrective maintenance, operator training or replacement of obsolescent equipment.
(l) improved safety conditions.
IMPACT OF PM IN EQUIPMENT MANAGEMENT
14. In the Army, equipment management aims at the RIGHT EQUIPMENT in the RIGHT PLACE at the RIGHT TIME in the RIGHT QUANTITY In the RIGHT CONDITION at the RIGHT COST, The objective is maximum availability at minimum costs or achieving the desired operational fitness at economic costs. This calls for optimising the reliability and maintainability standards and minimising the maintenance efforts.
15. Equipment management on scientific lines has become vital to ensure effective employment of weapons and equipment systems. This is particularly so when resources are limited and response periods for replenishment are long. 16. Army equipment must be physically tried out by the user and the maintenance personnel to assess its utility for introduction into service, its reliability and maintainability. The aim is to reduce the maintenance burden on the user. The aim of all equipment management in the Army is to create the user confidence in equipment and weapon systems.
17. During the in-service period, the user must ensure that its personnel are well trained to correctly operate and handle the equipment, maintain it to the extent required and thereby acquire maximum useful life out of it. This can only be achieved if PM consciousness permeates in the entire user set up and they have a high pride in equipment maintenance.
18. Since PM achieves desired operational fitness and maximum availability of equipment at economical costs, rich dividends can be reaped through PM for accomplishment of combat missions by commanders at all levels. It also develops increased awareness of personnel in maintaining the equipment and thereby enhancing the battle worthiness of equipment.
19. Ideally, all maintenance should be PM but such a situation is not economically feasible as equipment would be grossly over maintained. As PM checks are highly repetitive, good methods and procedures will add to over all efficiency. Written instructions coupled with on the job training will be highly cost effective and time saving. Standard procedures and defect analysis will aid troubleshooting or fault diagnosis. Establishment of date on defect fault co-relationship fault frequency and pattern of spares consumption will provide positive advantages in the form of better inventory control, improved training and saving in time, effort and money.
20. Concept of the PM is dynamic in nature and the decisions made and the proceduşey adopted are constantly changing. Thus it bears a great importance in equipment management which is a major contribution factor in the achievement of success in battle.
21. General Earl G Wheeler had said “As a prudent measure of combat effectiveness, we need to strengthen our maintenance system from the user level on back. We have to approach our maintenance with new enthusiasm and new insight. More importantly, we have better results. The demands of combat effectiveness permit no other course”
(a) Maintenance Management by Lawrence Man Tr.
(b) Effective maintenance Management by ET New Brough.
(c) Design-out Maintenance and Instrument Aids By Durgesh Chandra
(d) Preventive Maintenance – A handout by NPC.
(e) Proceedings of the Seminar on Engineering Support for Equipment Management 30 Nov. – 1 Dec. 72 at HQ Technical Group EME