ENGINE OVERHAUL AND REPAIR MANAGEMENT
Owners of Rolls-Royce 501K gas turbines are sometimes in danger of spending too much, or even not enough, for overhaul and repair services when they arise. Many decisions can be made by the customer that will have a dramatic difference in overhaul or repair cost, engine durability, and engine performance and longevity of service. TSS Ltd can help an owner to make decisions that will best balance overhaul or repair costs, reflecting that all important per fired hour cost.
Accepting there are a number of fundamental questions which arise when considering major repair and overhaul, let’s walk through some of these now: Click on the question of interest.
- ARE YOU READY FOR YOUR NEXT OVERHAUL?
- HOW CAN TURBINE SUPPORT SERVICES LTD HELP?
- WHY SHOULD AN OWNER PLAN IN ADVANCE?
- WHY USE OEM PARTS & MATERIAL?
- ARE YOU QUALIFIED TO MANAGE YOUR OWN OVERHAUL?
QUESTION: ARE YOU READY FOR YOUR NEXT OVERHAUL?
The length of service prior to overhaul for a gas turbine engine is a function of operating conditions, duty cycle, and many other factors. In general and as a rule of thumb, an operator of a Rolls-Royce 501K gas turbine engine with over 25,000 operating (fired) hours (TSN/TSO) should already be planning his next hot section overhaul.
Although heavily dependant on engine modification standards and firing turbine temperatures (TIT), by the time the engine reaches 30,000 hours, arrangements should be in place to remove the turbine module from service and either have it replaced on exchange, or route it for a zero-hour overhaul.
Typically, turbine module operation is currently limited to 35,000 to 40,000 hours due to lifecycle limitations on some of the key rotating components. Compressor modules are able to achieve in excess of 50,000 > Hrs, subject to efficiency.
QUESTION: WHY SHOULD AN OWNER PLAN IN ADVANCE?
It is not uncommon today for new replacement MRO parts to have lead-times from the OEM of six months or more. It is a fact that all modern manufacturing industries, including gas turbine manufacturers and their associated suppliers have reduced inventory levels to improve profitability, embrace lean flow manufacturing techniques and thus maximise shareholder value.
Further complicating the overhaul business is the availability of key hot section components in a variety of materials, designs and coatings. Some of these parts/coatings may be available only on a special order basis. A prudent owner will arrange for the pre-ordering of these key materials to insure that his turbine / compressor module will spend a minimum amount of time outside of the package.
Pre-ordering of parts also lends itself to modular exchange programmes, a highly viable alternative to current MRO practices.
QUESTION: ARE YOU QUALIFIED TO MANAGE YOUR OWN OVERHAUL?
For many owners the cost of a gas turbine engine overhaul is the largest single maintenance expenditure they will ever make. Such an enormous expense takes a high profile in any organisation and generally brings intense scrutiny from senior management. Further complicating the ability of an owner to plan and manage an overhaul is the fact that the event occurs once every four to five years. Typical turnover in operating and management personnel often results in the responsible parties facing their first and perhaps last and only overhaul. The hiring of an outside contractor, such as TSS Ltd, to assist the owner in the overhaul planning and implementation is a prudent and cost efficient investment that generally has a minimal payback period.
HOW CAN TURBINE SUPPORT SERVICES LTD HELP?
TSS Ltd does not itself currently overhaul gas turbine engines.
TSS Ltd does however provide an overhaul management consultancy service to Rolls-Royce 501K engine owner/operators and can arrange to manage overhauls/repairs at the workshop of a Rolls-Royce authorised facility (AMC). Unlike an owner who may face an overhaul every five years, TSS Ltd has experience of many engine overhauls, which are undertaken regularly each year. It is this imparting of experience in overhaul trends and cost effective techniques which adds value to the product.
TSS Ltd is constantly working with authorised companies on component selection and improvement of component repair(s) and process and techniques. TSS Ltd can match the hardware to best suit a particular application.
Beyond the selection of parts that must be replaced, many owners are surprised to learn that a large percentage of the parts are replaced or reworked at the discretion of the authorised facility and although there is an official "overhaul manual", there are a great many judgement calls involved which can have a major impact on the final cost to the customer, both in the short and long term.
It is a fact that given product developments, most Rolls-Royce 501K engine owners expect at least 35,000 hours between overhauls, yet the RR authorised facilities only generally guarantee only one year of operation. Crucial choices made by the RR authorised facility and the engine owner/operator will largely determine the durability of the engine during those hours from 8,000 to 35,000 and beyond, where the engine owner carries the full risk of unplanned maintenance and repairs including those which fall under the various contract exclusion titles.
TSS Ltd support will give the turbine owner the best chance of making prudent decisions in the engine overhaul and repair process.
The use of Rolls-Royce “authorised” new and refurbished parts has for 501K owner/operators been a question debated many times in recent years.
It is certainly true to say that in times gone by, non-OEM material was potentially of a lesser quality standard than that of the OEM material, and thus it was more susceptible to premature and catastrophic failure. However, with today’s modern and quality enriched manufacturing processes, this is not so much the case and most parts are sold “fit for purpose”.
In general terms, most operators who purchase and embody non-OEM material do so because of a perceived cost saving. But is that truly the case and who has the risk should a part fail? Quality, warranty, sustainability and cost are certainly factors for consideration in this decision making process.
Gas turbine engines are by default, highly tuned pieces of mechanical excellence, designed to rotate at high speeds whilst generating higher levels of energy. It is generally accepted therefore that companies which manufacture gas turbine engines are best suited to supply parts for gas turbine engines.
The policy of TSS is simple: TSS supports and actively promotes the use of OEM material at all times. TSS does also recognise that once purchased, ownership of an asset passes from business to customer. TSS acknowledges and respects the client’s rights and ability to make there own decisions.