Aircraft health monitoring and smarter maintenance started out decades ago with main propulsion engines. It stands to reason that some of the biggest opportunities to save money from predictive maintenance are for the components most similar to the big engines, auxiliary power units.
OEMs like Honeywell and United Technologies and MROs like Revima and AFI-KLM E&M’s EPCOR offer predictive tools for APUs. Revima Director of Fleet Management Mimi Correa says these tools provide significant benefits now and are on cusp of providing much bigger ones in the future.
Correa ticks off some benefits of APU predictive maintenance: improving availability with preventive maintenance before faults occur; reducing repair costs by preventing no fault founds and removals; and scheduling removals based on algorithms, not the soft times now used to limit disposal of APUs too damaged to be worth repairing.
For a fleet of ten aircraft with good maintenance data coming from the APU, Correa estimates current predictive applications can save about $300,000 in direct maintenance costs. Adding in revenue saved from reducing cancellations and delays would at least double those gains, she estimates, based on Revima’s experience with over 100 aircraft and information from several airlines, including Etihad Airways.
These are still early days in predictive maintenance for APUs. “Everyone says they are using big data, but currently we are really in the infancy of data collecting and not yet applying Big Data Analytics,” Correa argues. “The systems available mostly use simple changes in parameter trends and differences from expected APU performance for predictive maintenance.” The Revima exec estimates more sophisticated analysis of all data relevant to APU maintenance could double or triple the gains from trend analysis. And she thinks this next step will come fairly soon.
To take this next step, airlines need to team with a predictive maintenance supplier to share all APU data, including Aircraft Condition Monitoring reports, fault messages, as well as data from components in other relevant ATA chapters. Correa says it is difficult for an airline to hire and maintain data scientists to develop really sophisticated tools independently.
The trick may be getting the predictive service at the least cost. Several MROs and OEMs, and well as some independent firms, offer predictive services. Correa urges airlines that are sharing data to retain ownership of the data to ensure they will be able to negotiate the best contracts, not only now, but in the future. She believes MROs like Revima have a lean enough cost structure to be very competitive in this market.
So far, the company seems to be succeeding. Revima repairs about 500 APUs a years, and its predictive maintenance services increased 30% in 2017.