This page contains a Flash digital edition of a book.
FAILURE: ROOT CAUSE ANALYSIS


Recent turbine failures and the root cause


From lapses in


manufacturing quality to the introduction of new technologies, wind turbine


INTERMEDIATE PINION – CAUSE


components are still at risk of costly failures. Determining the root cause of the failure can not only prevent future liabilities for equipment manufacturers and reduce risk for operators but also improve production procedures and industry design standards.


The following recent wind turbine failures illustrate the Root Cause Analysis (RCA) process.


INTERMEDIATE PINION – PROBLEM


Multiple wind turbine gearboxes had catastrophic intermediate pinion failures during a similar timeframe. Gear tooth fractures resulted in liberated pieces of metal and consequential damage to other components. The gearboxes had been refurbished by an aftermarket supplier other than the OEM and had been in service less than 3 years.


Metallurgical analysis on cross- sections of the fractured teeth determined that the cracks originated at subsurface material defects. Further testing identified them as oxide inclusions containing aluminium and silicon. During normal cyclic loading the inclusions act as localised stress concentrations which cause cracks to form prematurely. It was determined that the batch of steel used by the gear supplier didn’t meet the cleanliness grade.


INTERMEDIATE PINION – SOLUTION A gearbox repair specification was established for the suppliers of the refurbished gearboxes which defines that material cleanliness must meet certain standards and gear manufacturing quality control processes must be added using non-destructive testing.


RCA BENEFITS


Intermediate pinion tooth fracture caused by a material defect


Gearboxes in the same batch were identified and proactively repaired, saving them from significant consequential damage. The supplier’s processes were improved by adhering to the stricter repair specification, a good outcome for both the owner and the supplier.


28


www.windenergynetwork.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92