0. Introduction

Our contribution towards a smooth operation

 In this guidebook problems and duties of the operator of a gas turbine should be made clear using the example of a owner- driver.

Even when we are well covered by insurance, this is no alternative for a operation without losses when we are permanently burdened with the feeling of uncertainty. At least deadlines will get into a misorder. Will planings fail trouble may be near.

We as technical thinking its a matter of cause to give attention to a „faithful friend“. That means we are willing to avoid at first problems, faults and failures. For this we have to pay attention to some things: Wear parts have to be replaced, commodities and additives have to be changed or added. We should also pay attention to outward appearances like ‘exhaust clouds’ or oil spills. So we look professionally during operation into every unnormal behavior. If our technical qualification is not good or sure enough, we delegat these tasks to an expert. We leave necessary repairs or overhauls to providers where we can expect competence and seriosity.

Such a care is not based on distrust about the reliability of our car. Rather we are pride about our contribution for a save operation. The car will thank us therefore reliableness so we can use it relaxed. This is also true for the „driver“ of a gas turbine.

You could make your own contribution towards letting this advantage work for you as long and as efficiently as possible. The present book will help you towards the understanding of relevant rules, manufacturers statements and specifications. It will also offer help in cases where you are required to handle things independently and serve as a means towards the active avoidance of problems, a strategy to be consciously practised, in order to operate a reliable engine.

Experience, gathered over years, is imparted in this book, which should accompany you in your role as a gas turbine operator and help make this long term investment a joy.

If we have based the acquisition of the gas turbine on the right criteria of choice, as described in chapter one, we have taken an important step towards a smooth operation, without which the second step, technical support, cannot be made.

To the normal operation behavior if a gas turbine belong:

  • Notably noises,
  • the leakage of air, gas oder auxiliary substances and operating fluids ( "Ill. 3.6.1-6"),
  • heavy vibrations ( "Ill. 4.1-11"),
  • formation of smoke,
  • intensive smell,
  • unnormal soot production,
  • flying sparcs in the exhaust gasstream (insofar the exhaus gas is observable).
  • external discolorations at the casings and on the piping system that indicate local overtemperatures ( "Ill. 4.1-10").


What one does not see through sufficiently can lead to serious problems through apparently incidental actions.

An important help to avoid failures and problems is the experience. Because there is always the maxim „get wise by failures“. Naturally we should aspire to collect experience without own failures and corresponding costs. For this reason we use in this book known examples. The long years experience presented in this book will accompany you on the way as gas turbine operator. So you will be sensibilized for the „desires and neede“ of your engine to have pleasure with it over a long time.

Did we succeed in taking the correct selection criteria (see Chapter 1) as a basis of the acquisition and found the corresponding gas turbine a first important step to a failure-free operation is done. This is the requirement for the successfull second step, the maintenance.

Our gas turbine needs technical support during the whole operation (Chapter 2). This begins with running it according to the rules. It includes the monitoring and goes beyond maintenance and overhaul (Chapter 4). This technical support naturally follows the manufacturer’s (OEM) statements and suggestions founded on experience and technical considerations (e.g. construction of the components, Chapter 4.1. Competent and motivated personnel, equipped with the necessary auxiliary materials, is required in order to understand and implement instructions. If the engine has finally been chosen under the aspect of friendly maintenance, our motivation is strengthened. Our personnel should also be in a position to avoid undesired operation conditions and to recognize and classify unusual operation behavior. It is not sufficient merely to observe the engine. Proper decision is dependent on one being in a position to evaluate which influence the periphery (Chapter 3.7) in front of and behind the engine can have. Instructions and handbooks should give sufficient and practical help to facilitate decisions. One can therefore react quickly and meaningfully, according to instructions, in unusual situations. The manufacturer has already contributed decisively to the success of our efforts through his instructions. Additionally, there are questions to answer such as:

  • Which parts should be operated until repairs on them are no longer possible?
  • Should new or repaired parts be used?
  • Which parts are repairable and when ?
  • Are the components life limited and according to which criteria?
  • Which are the necessary overhaul and inspection intervals?
  • How is maintenance to take place and what points should be considered?

One of our contributions to undisturbed operation will be to follow these instructions.

The following considerations show how multi - layered, e.g., the establishing of overhaul intervals is. As in all technical plants, the probability of the occurrence of failure changes according to the operation. It follows a “bath tub curve“ ( "Ill. 4.1-2").This performance shows that the failure rate does not automatically increase with the length of life. One has to reckon with multiple failures at the beginning of operation, which are to be traced back to problems related to production and assembly or lack of experience. That is why, e.g., the pass of test (Chapter 1.2.) and existing experiences are of special importance. On account of the initial, i.e., after each overhaul procedure renewed, ( "Ill. 4.1-2") higher failure probability alone, the overhaul interval should be possibly large, so that the period with lower failure probability, corresponding to the horizontal curve, is used as far as possible.

The preventing of failures by machine monitoring.

The prevention of failures is the best way for a reliable operation of your stationary gas turbine. An important help towards early failure recognition and the avoidance of failures is the continual monitoring and documentation (Chapter 5.1) of important operation parameter (temperature, speed, pressures, velocity of flow/flow rates etc.) and rating (e.g., frequency and acceleration of vibrations "Ill. 4.1-11").). The evaluation of these ratings for trend analyses, regarding the alterations of the degree of efficiency and operation performance („deterioration“), as well as for life monitoring, contributes towards the hindering of failures as a preventive security measure for failure avoidance ( "Ill. 5.1-5" and "Ill. 5.1-6"). We can also deduce important statements from regular analyses of filter residues, magnet chip detector deposits and oil samples ( "Ill. 3.5-4", "Ill. 3.5-5" and "Ill. 3.5-7").So measures for the engine safety to avoid failures become possible.

If, nevertheless, a failure occurs

If, nevertheless, problems or failures occur, a failure investigation with problem analysis is the condition for a selective and successful remedy. Such a problem/failur analysis has three main steps:

  • 1st step: Collection of Facts: To these belong the dokumentation of the operating data and the failure sequence. Keep in mind: the outcome can only be as reliable as the „quality of the facts“ allows. A frequent affirmation is recommended.
  • 2nd step: Developing of the hypothesis: This is normally carried out „creative“. A preselection between aggravating and favourite hypothesis is forbidden.
  • 3rd step: Verifying the hypothesis on basis of the facts: Of essential importance is that also apparently negligible discrepancies suspend a hypothesis. This can afford some iteration steps between the 2nd and 3rd step till a consistent theorie is found.

Such an approach has the benefit of transparency. The confirmability and traceability at a much later time is possible when new facts give doubt to the existing conclusion, for instance when against expectaion a parallel case occurred.

Parallel failures are often negated with the wrong argumentation, that there is apparently a different cause for every case. Such an argumentation usually ignores, that in the acute case several influences are failure causative effective. The different assessment usually emerges later in parallel cases as rather arbitrary.

Of course, the engine manufacturer (OEM) will maintain the right to take hold of the damaged part, although these belong to the operator - he paid for it! If the operator wishes to get a deeper glimpse into the failure, he should have the possibility of being able to bring in a specialist to carry out the examination and failure analysis, either separate from or with the manufacturer. This consultant should have the possibility for an information about the investigation activities of the OEM or an insurance company. In case the OEM makes the investigation it is anyway strongly recommended to fix priviously type, extent and deadline. The option for such an approach has to be early enough fixed, for example during acquisition of the engine. If not possible, there can not be reconed with a satisfactory feedback, at least from experience.

The option for such a manner of procedure should be discussed beforehand, e.g., when procuring the engine. In the rarest of cases, there is only one cause responsible for a failure. Experience shows that usually an interaction of many unfavorable influences lead to a failure. Consequently, one differentiates conciously between failure investigation and failure analysis. Failure investigation determines, with the aid of the most modern laboratory techniques, the findings of the failed parts, and, if necessary, the periphery. From that, the failure analysis works out the influences of the causes of failure and their emphases, by means of a recognized system. A typical sign of ineffective, corrective measures, e.g., through the manufacturer, a false emphasis of the influences or inadequate analysis, give rise to parallel failures for which there is apparently a different cause each time. Important aids to failure analysis are the records in the frame of the mentioned operation monitoring. Together with the trend, the time shortly before and during the failure occurence is important. A conclusive agreement of data is inevitable. It would be worth striving to gather the expensive and correspondingly valuable experiences for evaluation in a central documentation, so that the operator can derive optimum usage of the analyses of weak areas. The attitude that failures are not to be taken seriously, because an insurance company pays or the manufacturer guarantees, cannot be of long term advantage for the operator, as he does finally pay for the failure through high purchasing costs or premiums, to say nothing of irritations involved when a failure occurs.

To minimize those problems a statistic is needed. Therefore a cooperation of as much as possible opererators at least of the same engine type is recommended. A weak point analysis enables the development of directed and effective remedies. So the failure can be „a blessing in disguise“ for the operator and gives the chance to have a benefit despite the high costs. Often its a matter of a characteristic weakness of the particular engine type. Is this renowned by the operator, possible also new personnel that came with the new enging, it is possible by adequate advancement to avoid failures also over a long periods of time.

 Illustration 0-1

"Illustration 0-1": After a failure the question after prevention respectively remedies arises. Those are usually prepared/developed by the OEM and authorised from the agency in charge. The assignment occurres in the respectively suitable form conform to the mandatory procedures.

The picture shows on typical measures how it is possible to minimise the risk of failures. So especially in many cases so a further operation or short time recommissioning is possible. Measures first are based on instructions, respectively overhaul and maintenance manuals. Ar the definitions and descriptions of toöeerable flaws respectively specific approaches unsatisfactorily the OEM must be consulted.

Supervisory measures come into consideration, when the failure did not yet lead to impermissible consequences or an unbearable risk. Examples are slow propagating or resting thermal fatigue cracks in static parts (e.g., combustion chamber, "Ill. 3.2.3-1"; or turbine guide vanes, "Ill. 3.3-9").

Boreskopinspektions permit preventing surveys, e.g., FOD at the blading.

Non destructive testing (NDT) like inspections with penetrant, eddy current or ultrasonic can ( "Ill. 5.3-3") be carried out in the assembled situation when the position and size of the failure is convenient or the part is tempeorarily disassembled (e.g., at blade roots).

Chip control (oil, fuel) of filters ( "Ill. 3.5-3")and magnetic chip plugs ( "Ill. 3.5-5") can as well show the begin of a failure, as permit conclusions on concerned parts.

Operation limitations will be normally necessary, if at least over a certain time, we „can/must live with the failure“. That is the case when there is no time for specific measures or the lack of spare parts. The constraints comply with the mechanism and the progress of the failure.

During fatigue problems in the LCF- region, like under cyclic laoads of discs or thermal fatigue of hot parts, frequently the number of starts till the exchange will be limited. Thereby the crack propagation ( "Ill. 5.3-1"), in relation to the starts and/or operation time must be known. That requires an analysis of the fracture surfaces of the failed parts. Also an abatement ot the thermal stresses and temperature peaks with an optimised, respectively „cautious“ start procedure can be promising ( "Ill. 3.3-5").

Problems with impermissible heavy oxidation will rather demand a constraint of the operation lifetime.

Elevated temperatures of the blading by clogging of cooling passages or unfavourable temperature distribution in the hot gas ( "Ill. 3.3-11") can make it inevitable to limit the performance.

Repairs on site are limited to manual instructions. To this belongs, e.g., the smoothening of mechanical damages (FODs) on the blading ( "Ill."). Cracks in gas ducts behind the gas turbine can often be repaired by welding. In some cases, in which no unacceptable leakage is to be expected, the crack propagation can be slowed by drilling a hole.

Maintenance can prevent failures with additional measures. To these belong especial efforts for the cleaning of the compressor blading ( "Ill. 4.2-1.1" and "Ill. 4.2-1.2") and/or the turbine. Further, frequent checks of the oil (oil analysis, "Ill. 3.5-4") can assure the operation. Also a lubrication, improved or adapted to the problem, can ease difficulties with sluggish or stuck parts.

Exchange and reconditioning of aggrieved components. To those belong blades with critical fretting, or hot parts (turbine blades, combustion chamber) with damages by thermal fatigue or oxidation. If there are not yet fatigue cracks at potential endangered parts, shot peening can minimise the risk.

What can be learned from failure statistics:

For the car driver, failure statistics make for interesting and variously useful reading: they help him in choosing a new car, reveal the possible weak spots of his present one, and prompt him to timely sale. The gas turbine operator can gain similar knowledge from experiences represented in statistic evaluation of failures. This includes evidence to prevent failures, as well as help in the evaluation of an engine to be acquired or procedures during operation and repairs.

Useful publications originate primarily from engine insurance companies. Here one can assume a similarity of interests with the operator: the wish to prevent failures, which is why the statements of the insurer are especially significant.

According to R.E. Dundas (Lit 0-1), the component dependent failure costs on engine derivates in individual cases differ absolutely from the corresponding costs on heavy frame engines (HFM). "Ill. 0-2" reveals these connections and one can recognize that a higher portion of the failures are to be blamed, at least partly, on the manufacturer. Uprating through steam injection ( "Ill. 2.1-3.4" und "Ill. 3.2.2-3") has, in the time of evaluation, led to numerous very costly failures, illuminating the problematic of new technologies and the subsequent power increase. The failure behavior is also different in the ranges of performances of derivates and HFM ( "Ill. 0-3").

J.Leopold observes ( "Ill. 0-4") the primary causes, i.e., the actual causes of failures and affected parts (Lit 0-2). "Ill. 0-5" shows the high percentage of product faults, mainly problems for which the manufacturer is responsible. These failures had, indeed, apparently slightly receded in the newer period of evaluation time, but are still of a very high niveau. The introduction of new technologies, the further improvement in the degree of efficiency, e.g., temperature increases in the hot gas area, as well as performance increase did not bring about any decisive diminishing of the problems to be expected. In "Ill. 0-5", the performance of individual components beyond operation time is represented. Here also, turbine blades and guide vanes are strongly failure prone.The maximum failures appear at the time of revision, as here, the damages were discovered before the breakdown of the engine and are to be booked as repair or replacement costs.

"Ill. 0-5" (Lit. 0-4) shows the course of failure frequency at operation time. It is remarkable that special causes of failure show a typical distribution of incidents in the course of operation. The phenomenon of the „bath tub curve“ should be mentioned here (compare "Ill. 4.1-9").

"Ill. 0-7" can serve as a direct comparison between the variations of aero engines and the derivates belonging to them (Lit.0-5), although the evaluations date back very long. The main difference is that the life limitation caused the repairs of the aero engines, whereas acute problems on turbine and compressor were the cause of derivate repairs. An explanation could be that the derivate was run without a corresponding life limitation, until the problem appeared at the parts, while at the areo engines the philosophy of safety of aviation units came into consideration.

 Illustration 0-2

"Illustration 0-2": (Lit. 0-1): This relevant literature (Lit.0-1) from the year 1994, regarding the evaluation of failures on industry gas turbines in the USA, enables us to draw some interesting conclusions. Such a statistic is dependent on the number and the type of individual engines and is, therefore. limited in it’s general validity. It is connected with cause related costs of individual failures, divided between engine derivates and heavy frame engines ( "Ill. 2.1-7" and "Ill. 2.1-8").

Combined causes of failure:

Stall in the compressor: This is apparently much more expensive for aero engine derivates as for heavy frame engines. Up until 5 years ago the failures on derivates often occurred in relation to steam injection in order to uprate performance. This shifted the operation point of the compressor to the surge line ( "Ill. 3.1.1-1"). As a result, the stall was so violent that massive destruction in the compressor took place. Through appropriate monitoring and control of the engine such problems can be overcome. This can serve as an example for the problem of uprating performance ( "Ill. 2.1-3.4").

Fatigue failure (HCF) on compressor blades: This concerns a type of failure for which the manufacturer is responsible in most cases. The compressor guide vanes in base load engines seem to be especially affected, which is actually surprising as the engines run in a small operation speed band, with relatively few start cycles. Thus, a dangerously long operation in the resonance area of the blades should be simpler to avoid during design, as derivates with typical peak load operation. The extensive trials of the engine variations, with their typically large number of engines, possibly play a part in the safe control of the frequent load changes and start cycles.

Fatigue failures (HCF) on turbine blades: The cost of damages for heavy frame engines are clearly higher than for derivates. It appears that the derivates also profit here from the extensive trials of engine variants. These failures usually fall in the area of responsibility of the manufacturer. The cause is mainly the excitation of the blade in the resonance ( "Ill."), through periodical disturbances of flow in the gas duct. Even flutter excitation, (self exciting aerodynamic process), was identified as a cause of failure. In the blade tip area, relatively thin, turbine rotor blades, (narrow chord), were endangered by engines whose performance was uprated. Here also, the problem of uprating is clearly seen.

Failures on engine derivatives ( "Ill. 2.1-7").

Thermal crack initiation (thermal fatigue, "Ill. 3.3-16"): In connection with the steam injection to increase performance, crack initiation followed, in the area of struts, at the turbine casings of a particular manufacturer. More precise details are not given in the literature: it seems to concern crack initiation that occurred because of higher thermal stresses.

Turbine disc failure: This has apparently to do with a design weak point (notch, "Ill. and 6" to "Ill. and 8") on the discs of a certain type of engine that led to LCF fatigue ( "Ill. 2.2-5" and "Ill." ), through start cycles, and is thus life limited.

Damages on heavy frame engines ( "Ill. 2.1-8")

Cooling air loss on T-rotor blades occurred apparently only on heavy frame engines with an extreme external air/air cooling system, that, after malfunctioning of the steam injection, developed internal icing on being shut down. Thus, there was insufficient cooling air for the hot parts and the outcome was creep failure, apparently first noticed after longer runs. Not only were turbine rotor blades affected but also the turbine discs belonging to them. In such an arrangement, a monitoring of the cooling air flow is urgently recommended to stop this kind of ‘creeping’ damage’ in time.

Creep fractures ( "Ill. 2.3-1" and "Ill. 2.3-2") on turbine blades: They are often the consequence of insufficient cooling air. This situation can enter when the manufacturer had underestimated, e.g., the deterioration of the sealing systems ( "Ill. 1.1-3" and "Ill. 3.3-11") during operation, or material data was unduly optimistically extrapolated concerning long running times.

Also clogging in the cooling system by intake of dust or forbidden intensive oxidation can trigger creep damages ( "Ill. 3.3-12"). A similar effect can be expected if material data were i mproper optimistic extrapolated for long durations or the operator ignored the advised (OEM) lifetime.

Internal fire and explosions: These events are closely connected to the extinguishing of the combustion or instant shut down, and insufficient drainage of the residue fuel at the end. A special problematik are backlashs of the flame ( "Ill. 3.2.1-5.2") or self-ignition in premixers of combustion chambers. In derivates of aircraft engines with titanium alloy compressor blades a titanium fire as secondary damage (for example after a blade failure) can not be ruled out (in this Ill. not documented).

 Illustration 0-3

"Illustration 0-3": In this picture (Lit 0-1), the percentage of the engines and the distribution of the failures according to performance classes is represented. The sum of the percentage of all performance classes is 100%. Further, the failure costs pro kilowatt, given delivered output, is shown. The evaluation is related to the statements of many insurance firms in the USA.

Performance range up to 9000 Kilowatts: Contrary to expectations, clearly a lesser number of derivates in the relatively lower performance range up to 9000 kilowatts is insured than heavy frame engines (HFM). If one relates the failure costs of the installed kilowatts and compares the range of both engine concepts up to 9000 kilowatts, one notices that the failure of a HFM causes higher average costs as those for a „derivate“. Against that, the percentage of the HFM failures in the performance area up to 9000 kilowatts is lower than the comparative value for derivates. This can be due to the different operation cycles. For the HFM, the base load operation is typical, for the derivate, the peak load operation. These differences are most noticeable in engines up to 1500 kilowatts. Apparently, derivates have less frequent failures. If a HFM breaks down, one has to reckon with higher costs. The costs of the unavailability of the engine, surely higher for engines that deliver base load than for those with peak load, are not given.

Performance class 9000 to 25000 kilowatts: Almost 80% of all derivates find themselves in this performance range, against only approximately 20% of the HFM. In this performance range, the failure rate and costs of moderate failures between both engines are absolutely comparable.

Performance range above 25000 kilowatts: It is noticeable that the share of the affected engine on the current total number is many times higher in derivates as in HFM (700000 kilowatts). Against that the moderate failure costs are thoroughly comparable.

Conclusion: Heavy frame machines show comparatively fewer failures in the lower and higher performance range, but are very costly in lower classes relative to output performance. In the middle performance range, there is hardly any difference between the failure performances of HFM and derivates. It is to be hoped that a levelling of failures to a lower niveau will be reached for all classes of performances.

 Illustration 0-4

"Illustration 0-4": This illustration touches upon works from J.Leopold (Lit.0-2) from the years 1980 (time period 1970 up to 1979 with approx. 240 failures) and 1987 (time period 1981 up to 1986 with over 180 failures). 110 engines were observed (1980) with a performance of 900 kilowatts up to 88 MW. The variation of the distribution over the years is of interest next to the distribution of the causes of failure and affected parts, from which, information regarding the developments and successes of failure prevention are to be expected.

Causes of failure: The biggest share of failures is to be traced back to so called product defects. These are faults that, true to definition, are the responsibility of the manufacturer, planning and assembly. Around 20% of the causes of failures are due to operation faults, divided equally between maintenance and service failures.

Affected parts: Hot parts in the combustor and turbine are most affected, whereas turbine rotor blades and guide vanes take the lion’s share. In contrast, failures in the compressor area are clearly more seldom. The relatively high share of bearing failures is remarkable (Chapter 3.5.2). Valves, air passages and pipes are not to be overlooked in this regard.

Trends and conclusions: Product defects have slightly decreased with time, but are still numerous. What J.Leopold found already in 1980 may still be valid: „Despite extensive efforts to repair, on the grounds of earlier failure trends in new developments, the improved version was not always defect free. Weak points in the design were clear only after many more running hours and starts“. The increase of service faults to above 20% was traced back to a clear increase in maintenance faults, while service defects drop under 5%. This spoke of an increase in the competence of the service personnel. The share of foreign objects (Chapter as a primary cause of failure was given as approximately 10%, which justified higher efforts towards their avoidance.

 Illustration 0-5

"Illustration 0-5": The background to this evaluation is described in Fig.-3. This is related to statements from J.Leopold from the year 1980 (Lit.0-2), but can still be evaluated as a remarkable and impressive confirmation of the bath tub shape of failure frequency being above that of operation time ( "Ill. 4.1-9").

Conspiciuous is, that the installation and early guarantee phase shows an especially high failure incidence on hot parts, although one should actually expect long term failures at these parts at a later point of time. There follows a phase with a relative low failure rate, which then clearly increases during the time of big inspections (Chapter 4.1.2) between 15000 and 20000 operation hours. As reason for these observations, Leopold says that one recognizes these weak spots only on opening the engine. In the following phase, new improvements and alterations in the form of a lower failure rate seem to prevail.

 [[@en:0:ex_en0dash1.svg|Example 0-1]]

Example 0-1: During the inspection of an opened „pipeline-gas turbine“ a further gas turbine in full operation was running nearby. When passing by it, the air jet from this not to be inspected engine was clearly felt. A search for the cause showed that an air removal pipe in the machine was already torn. A complete disruption of this hot air pipe was imminent, which may have resulted in comsiderable life-endangering damage. The operator was unaware of this situation, although he was often in this area during the day. Possibly a certain „blindness to schortcomings“ in the daily work played a role.

 Illustration 0-6

"Illustration 0-6": In this presentation, according to T.D.Matteson (Lit0-4), it is recognizable that at least in flight engines, most failures (about 90%) do not show any definite increase with operation time. It is, however, to be seen that cost intensive, hot part and compressor failures like fatigue ( "Ill. 2.2-5" ) and creep ( "Ill. 2.3-2" and "Ill. 2.3-3") show a typical operation time dependency.

Despite that, maintenance and inspection procedures needs to be worked out ( "Ill. 4.1-1") which minimize revisions with disassembly. Progress in the monitoring sensors allow new perspectives also in industrial use. The progress in control/ monitoring (Chapter 5.1.1) and the sensor technology allow also in the industrial use new prospects.

 Illustration 0-7

"Illustration 0-7": This workout (Lit.0-5) was carried out by an overhaul shop and originated as early as 1974. It shows experiences with the aero engine type JT-4 and compares this with the derivate GG4.

With these types of engines, except for bearing and oil system problems, there seem to be serious differences between derivate and aero engine. Thus, the reasons for the repairs on the engine version are the given lifetime limitations. In derivates, the problems relate to the compressor and turbine. The high share of foreign object damages is noticeable when it comes to industrial use, whereas it is rather to be expected that aero engines have more problems due to the intake of foreign objects. That there was a lack of filters in front of engines in the early seventies, or that they were less effective is no plausible explanation for the high foreign object attack.

Conclusion: The weak spots of engines and their derivates can be very different.The steady state operation in industrial use strains the engine apparently differently. These problems show up only in long term use. The stationary use in the industry application seems to demand the engins different than in air traffic. Often the difference becomes clear in the temporal distribution ( "Ill. 0-5").

Literature of chapter 0

Lit. 0-1 R.E.Dundas,“A Statistical Study of Gas Turbine Losses and Analysis of Causes and Optimum Methods of Prevention“, ASME Paper 94-GT-297, (1994).

Lit. 0-2 J.Leopold, Allianz Versicherungs-AG, „Experience with Stationary Gas Turbines of Modern Design“, Der Maschinenschaden, Vol 53 (1980).

Lit. 0-3 J.Leopold, Allianz Versicherungs-AG,“Bemerkenswerte Schäden an Industriegasturbinen“, Der Maschinenschaden 61 (1988) Heft 3.

Lit. 0-4 T.D.Matteson,“Do We Really Understand Maintenance?“, AIAA, New York, NY, USA (1987).

Lit. 0-5 J.K.Goodwine,R.C.Stradley,“Maintenance Considerations in Aircraft-Derivative Industrial Gas Turbines“,SAE Paper 740847 (1974).

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