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- Block, J., et al.
(författare)
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Evaluation of preventive maintenance task intervals using field data from a complete life cycle
- 2008
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Ingår i: IEEE Aerospace Conference Proceedings. - Piscataway, N.J : IEEE Communications Society. - 9781424414871 ; , s. 1-11
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Konferensbidrag (refereegranskat)abstract
- In this paper the appropriateness of initial preventive maintenance task intervals and the improvement of changed intervals are evaluated. The evaluation criteria are partly derived from logic found in the RCM (Reliability-Centered Maintenance) methodology. Empirical data is related to the whole life cycle of the Swedish military aircraft system FPL 37 Viggen, from 1977 to 2006. The analysis shows that the maintenance intervals are partly appropriate and that some performed changes are improvements. These conclusions are strengthened if the phase-out of the aircraft system is considered, where the preventive maintenance strategy has been replaced with a corrective one, in order to achieve cost-effectiveness. Considering the perfect repair assumption, it seems that the overhaul tasks essentially bring the items back to a state as good as new. The performed evaluation mostly considers when the failures are recognized, i.e. during operation or during maintenance. Hence, aspects such as item accessibility, personnel skill levels, and maintenance task intervals for other items are not included in the evaluation.
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| 2. |
- Block, Jan, et al.
(författare)
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No Fault Found events during the operational life of military aircraft items
- 2009
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Ingår i: 8th International Conference on Reliability, Maintainability and Safety, 2009. - Piscataway, NJ : IEEE Communications Society. - 9781424449040 ; , s. 920-924
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Konferensbidrag (refereegranskat)abstract
- No fault found (NFF) events are critical and well-known problems for certain aircraft items. This paper presents a study of these events for repairable items with on-condition maintenance, based on operational data from a military aircraft. Some findings are that: the number of NFF events is influenced by item type and number of repairs; most NFF events are initiated by faults recognized during operation; and different inspections contribute to NFF events. Hence, item design and tests at different operational modes and maintenance echelons should be better aligned to reduce the number of NFF events
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| 3. |
- Block, T, et al.
(författare)
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Diagnostic accuracy of plasma biomarkers for intestinal ischaemia
- 2008
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 68:3, s. 242-248
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Intestinal ischaemia is a life‐threatening condition with high mortality, and the lack of accurate and readily available diagnostic methods often results in delay in diagnosis and treatment. The aim of this study was to investigate the accuracy of different plasma biomarkers in diagnosing intestinal ischaemia. Material and methods. Prospective inclusion of patients older than 50 years with acute abdomen admitted to hospital in Karlskrona, Sweden, between 2001 and 2003. Venous blood was sampled prior to any surgery and within 24h from onset of pain. D‐lactate, alpha glutathione S‐transferase, intestinal fatty acid binding protein, creatine kinase B, isoenzymes of lactate dehydrogenase (LD) and alkaline liver phosphatase (ALP) were analysed. D‐dimer was analysed using four different commercially available test kits. Results. In‐hospital mortalities among patients with (n = 10) and without (n = 61) intestinal ischaemia were 40% and 3%, respectively (p = 0.003). D‐dimer was associated with intestinal ischaemia (p = 0.001) independently of which assay was used. No patient presenting with a normal D‐dimer had intestinal ischaemia. D‐dimer >0.9mg/L had a specificity, sensitivity and accuracy of 82%, 60% and 79%, respectively. Total LD, isoenzymes of LD 1–4 and liver isoenzyme of ALP (ALP liver) were significantly higher in patients with intestinal ischaemia, and accuracies for LD 2 (cut‐off 2.3µkat/L) and ALP liver (cut‐off 0.7µkat/L) were 69% and 66%, respectively. Conclusions. D‐dimer may be used as an exclusion test for intestinal ischaemia, but lacks specificity. The other plasma biomarkers studied had insufficient accuracy for this group of patients. Further studies are needed.
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