The Impact of Utilization and Ageing on Aircraft Valuation 10 October 2013 John Nazareth Senior Reliability Specialist Maintenance Engineering
Introduction In this presentation I will show that aircraft with higher utilization business operators should have an equivalent or higher reliability than those with lower utilization operators This is the result of Bombardier s design practices The relationship between utilization and Dispatch Reliability The impact of maintenance programs on higher utilization aircraft Some conclusions from the study of ageing on commercial aircraft will be presented. 2
Design Practices We have the same design teams for business and commercial aircraft. Our commercial jets are designed to fly 60,000 flight-hours in 30 years, and many of our aircraft have already crossed 45,000 flight-hours. These same design practices are used for all our aircraft. None of the business jets even the higher utilization aircraft, will come close to this kind of utilization.
Design Practices Maintenance Program The maintenance programs prepared by Bombardier are designed strategically so as to keep the aircraft reliability at a constant high level. Rotable components are changed when they fail. Items with known life are replaced at fixed times with new/overhauled units
Observations on Utilization and Reliability Studies done by Maintenance Engineering in the past showed that aircraft that have an annual utilization above 1000 flight-hours have higher component reliability than aircraft flying below that level of utilization. That is so because the failure rate of components is partially dependent on component usage and partly on elapsed time (because of environmental impact). At annual utilizations above 1000, elapsed time plays only a small factor. Since reliability is calculated in terms of failures per flight-hour, the component reliability improves at the higher utilization. Higher utilization means that more components will have been changed. This gives a higher opportunity for the incorporation of higher reliability modifications. Thus aircraft that operate for higher utilization operators have a better reliability.
Study on Ageing of Commercial Aircraft Aging studies were performed on each of the 4 commercial aircraft programs we have designed: CRJ100/200, CRJ700/900/1000, Dash 8 (Q100/200/300), and Q400. Here are the results: CRJ100/200: 20 years into the program s life, the aircraft does not show significant impact of ageing on the Dispatch Reliability of the aircraft. This shows that regular maintenance and mod programs that are carried out maintains the good reliability of the aircraft. 20 aircraft have attained an age of 40000 FH and higher, another 80 have attained between 35-40000 FH. CRJ700/900/1000: 12 years into the program s life, the aircraft shows no signs of ageing on the Dispatch Reliability. 240 aircraft have attained 20000 FH or higher.
Study on Ageing of Commercial Aircraft (cont.) Dash 8 (Q100/200/300): 29 years into the program s life, the aircraft shows only a minor level of ageing on the Dispatch Reliability. Because of this, there was demand for extending the life of the aircraft (under implementation of a special Service Bulletin) to 120,000 Flight Cycles. 20 aircraft have attained in excess of 60000 FH, and a further 77 have attained between 50-60000 FH. Q400: 13 years into the program s life, the aircraft shows no signs of ageing on the Dispatch Reliability. 33 aircraft have attained 20000 FH or higher. (Cycles have a larger impact on turboprops as their stage lengths are shorter than jets.) Thus, even at a higher utilization, business aircraft should retain their high reliability, and hence, value.
Bombardier s Unique Position There isn t another large manufacturer of business aircraft that at the same time produces a large number of commercial aircraft. This fact allows Bombardier to have a pool of lessons learned (from high-utilization commercial aircraft) which we leverage to enhance the design of business aircraft. Bombardier collects more reliability data on its aircraft than any other aircraft manufacturer in the world. We are also a world leader in the analysis of such data. The knowledge so gained is used in designing better products, keeping maintenance at a minimum without impacting reliability, and working with operators to lower maintenance cost.
Bombardier s Unique Position (Cont.) Bombardier has used this knowledge to help the whole industry in that we have played a leading role in the creation of SPEC2000 Chapter 11 a specification that defines the maintenance data that is most useful in improving aircraft reliability. Bombardier has also been a leader in the creation of new reliability metrics for the industry - SPEC2000 Chapter 13.
Summary Because of a common design team (in Bombardier) between business and commercial aircraft, the robustness of our designs ensure that within the range of utilizations of our business products, the value of the aircraft are not adversely impacted by higher utilization. The use of rotable components with aircraft and their planned overhaul ensures that the aircraft are always kept in a good state of operation Higher utilization aircraft tend to exhibit higher reliability. Because of the trade-off, the aircraft used by companies like high utilization operators should have an equal value to similar aged aircraft that operate with private owners.