Power of Performance is as Easy as APU

When you hear the words “jet engine” you probably think of the large, powerful and reliable propulsion engines that hang on the wings of airliners and business aircraft, power military fighters and keep the rotors turning on helicopters. But don’t forget that most aircraft also have another jet engine onboard, called the auxiliary power unit, or APU.

APUs are smaller turbine engines that usually reside in the aircraft’s tail section. They make flying safer, more efficient and more comfortable. They generate electric power to run the air conditioning, lights, communications system and cockpit displays while the aircraft is on the ground. When needed, an APU can restart an engine or provide power to the cabin and cockpit during flight.

The most famous example is the “Miracle on the Hudson” landing by Capt. Sully Sullenberger. After his main engines were disabled in a bird strike, Sully fired up the Honeywell 131-9A APU on his Airbus 320. It provided the power he needed to use his avionics and control surfaces to execute the one-shot river landing and save the lives of 155 passengers and crew members.

Of course, heroic landings are the exception. Honeywell APUs usually live a much quieter “life,” reliably providing secondary power on tens-of-thousands of flights worldwide every day. We’ve had a lot of experience in the field and have produced more APUs than anyone else – more than 100,000 since we introduced the first one in the mid-1950s.

APU technology has come a long way since then and our talented APU engineering team is constantly boosting the performance of our products, which equip commercial, business and military aircraft and helicopters. Today, we provide the industry’s widest range of secondary power solutions ranging from smaller engines that provide around 100 shaft horsepower to our most powerful, which generates 1,700 shp.

Our latest APUs, like the HGT1700 that flies on the Airbus A350, truly represent the state of the art and are much more powerful, efficient and reliable than previous generations of systems. The HGT1700 features variable speed capability to increase starting power while lowering specific fuel consumption by 6-10 percent.

Our APU product line has been at the forefront of Honeywell’s GoDirect Connected Maintenance portfolio of solutions, which now extends to systems throughout the aircraft. For our connected APU offering, we collect data and use advanced data analytics to predict when a part will fail, 4-5 days in advance. This lets operators address problems before they can disrupt normal operations. Some of our connected APU customers have seen a 35 percent reduction in APU-related flight delays.

We’re now looking for opportunities to expand our software and service offerings for both airlines and business aviation operators, building on Honeywell’s core strengths in data analytics, prognostics, and predictive and prescriptive maintenance. For example, we’re ready to show how connected maintenance can reduce downtime and maintenance costs for business aviation operators.

Looking back, we’ve seen a consistent increase in the demand power on the aircraft. Looking ahead, we see the trend continuing as aircraft become more connected, electric and autonomous. Before long APUs will routinely provide power during flight for environmental controls, avionics, wing anti-icing and other aircraft systems – all while using less fuel than the propulsion engines that generate power for those purposes today.

With this in mind, Honeywell is already working on new secondary-power solutions that will meet the needs of the next generation of aircraft for APUs that are even more powerful, reliable and fuel efficient than the ones we have today.