Keeping APUs Humming.jpg Cathay Pacific

Keeping APUs Humming: The Airline View

Cathay Pacific looks to gain increases in APU reliability.

Cathay Pacific Airways has made substantial progress in increasing the reliability of, and speeding the repairs of, its auxiliary power units (APUs) with the help of APU-OEM Honeywell. The carrier is looking into expanding its use of Honeywell’s predictive maintenance tools, says Philippe Christol, technical services manager for powerplants in Cathay’s engineering department.

The new initiative has already given Cathay a significant increase in APU reliability. There has been a 13% reduction in inoperable APUs, a 14% cut in the number of delayed flights and a 26% reduction in the duration of delays. These gains have been achieved by just addressing a portion of possible APU defects.

APUs to cool cabins and provide customer comfort are critical in Hong Kong’s warmish climate, notes Christol. Yet APU reliability had sometimes been an issue on Airbus A330s, and traditional APU troubleshooting took significant time. As at other airlines, on-time performance for Cathay is a key service goal.

So about a year ago, Cathay Pacific and Honeywell jointly agreed to launch an initiative aimed at developing a predictive maintenance tool. Honeywell suggested that if Cathay Pacific could provide data from quick access recorders, aircraft health management and pilot reports, the OEM could predict which APU line replaceable unit was likely to fail. The airline gave Honeywell a year of proprietary QAR, AHM and pilot data, and Honeywell developed algorithms to look for significant trends. The data covered 61 A330s operated by Cathay and its regional subsidiary Cathay Dragon.

The Honeywell approach worked, at least for the five LRUs it initially looked at. Four of these were APU LRUs. The other LRU was related to, but not actually a part of, the APU. The Honeywell system works similarly to health monitoring of main engines: Honeywell recommends the component to be removed before it actually fails. The recommendations are right 90 to 95% of the time, Christol estimates.

Moreover, providing Honeywell with the data was relatively easy, as Cathay gets pilot reports from its Ultramain tech log and receives QAR and health data from Airbus’ AIRMAN service.

Cathay and Honeywell have now begun another program. Instead of predicting failures, this one will accelerate troubleshooting after an APU failure by focusing on the most likely cause of the problem. The carrier is also considering extending the predictive approach on Airbus APUs to its Boeing 777 fleet and to predicting failures of more non-APU components that could affect APUs, for example fuel-system components.

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