What It’s Like to Work on a Chinook T55 Engine

It’s no surprise that Anthony San Filippo knows the T55 turboshaft engine like the back of his hand. After all, he’s been working on the venerable engine since 2003, the year he joined Honeywell as a T55 maintenance technician in Greer, South Carolina.

“My dad was in the Navy and I wanted to be a pilot when I was a kid,” he remembers. “But as I got a little older, the mechanical side of aviation really caught my attention. I went to school to be an airframe mechanic and aircraft maintenance tech, so when I graduated and got the chance to work at the Honeywell maintenance, repair and overhaul (MRO) facility, I took it.”

Working on the best

Working on the Honeywell T55, the engine that powers the legendary CH-47 Chinook twin-rotor helicopter, was a real eye-opener for Anthony. “There is no substitute for hands-on experience,” he said. “I was lucky enough to work with some very good technicians at Honeywell who taught me all about these amazing engines and how they work, from the inside out.”

Anthony was able to take what he learned at Honeywell to his next job at a civilian CH-47 operator, Columbia Helicopters in Oregon. During his almost 16 years at Columbia, he worked on the T55 and the AL5512, a commercial T55 variant.

“We did everything from performing routine maintenance on the engine, to overhauling the gearboxes and compressor, to traveling to remote locations to work on the aircraft,” Anthony said. “Working in the field can be very challenging, but it’s also rewarding and a lot of fun. You actually become an extension of the flight crew for however long the repair takes. Your job is to solve a problem so the crew can complete their mission and return to base.” 

Elevating careers and Chinooks alike

In 2021, Anthony joined Billings Flying Service, a Montana-based operator of CH-47 helicopters used for aerial firefighting and heavy-lift missions, as director of MRO. At Billings, his team of seven handles end-to-end MRO for the company’s seven Chinooks, one UH-60A and two Bell 206Ls.

Over the course of his career, Anthony has flown to remote locations like Afghanistan, Ecuador and Papua New Guinea to service T55 engines in the field. “One of the great things about this engine is that it is easy to work on with minimal specialized ground equipment, which really helps us find and address problems quickly and get the helicopter back in the air, where it belongs,” he said.

“I remember flying to Ecuador with a gearbox and some other parts in my suitcase,” he added. “I arrived after just two hours of sleep and a five-hour drive, only to find that the problem wasn’t in the gearbox at all. Fortunately, I was able to troubleshoot the engine and get the right parts ordered to make the necessary repairs.”

Anthony finds it satisfying to work directly with pilots and crew chiefs, who have a unique understanding of their aircraft and its engines. “I once took a check-flight with a CH-47 crew after an engine change, which was an amazing experience,” he said. “Pilots and crew chiefs love to fly the CH-47 and they know they can count on the T55 engines to deliver the power they need, when they need it.” 

The T55 is legendary for the right reasons

After almost 20 years of working on the T55, Anthony is still impressed with the Honeywell engine. “It’s almost without fault and it’s fairly simple to work on. I call it a ‘squatty little powerhouse’ because it’s so compact and powerful.”

A pair of T55 engines has powered every Chinook since the helicopter made its maiden flight in 1961. Honeywell has produced more than 6,000 T55 engines, which have flown over 12 million hours. The company is currently testing the newest version of the engine, the T55-714C, which is much more powerful and reliable than its predecessors.