GE Aviation has tested a 35% additive manufactured demonstrator engine to validate 12 additive parts in its Advanced Turboprop engine.
The ATP engine is set to power the all-new Cessna Denali single-engine aircraft. The additive components, which have replaced 855 subtractive manufactured parts, will reduce the ATP’s weight by 5% while contributing a 1% improvement in specific fuel consumption.
An additive CT7-2E1 technology demonstrator engine, which reduced over 900 subtractive manufactured parts to 16 additive manufactured parts, was used as inspiration for the architecture of the ATP engine. It also allowed for part commonality between the two additive test programs.
GE’s ATP will utilise more additive parts than any production engine in aviation history. The 12 additive parts include sumps, bearing housings, frames, exhaust case, combustor liner, heat exchangers and stationary flowpath components.
A team of eight engineers, who designed the additive fuel nozzle tip on the CFM LEAP engine, led the design effort for the 16 additive parts tested in the CT7. GE is building more additive hardware for additional CT7 tests, which will include even more additive parts than the first test. These additive components for CT7 and ATP tests are built at GE Aviation’s Additive Development Centre in Ohio. The first full test of the ATP engine is expected to be conducted before the end of 2017.
“With subtractive manufactured parts and assemblies, you traditionally use bolts, welds or other interfaces to attach the parts together, which adds weight to the engine,” said Gordon Follin, ATP Engineering GM at GE Aviation. “On the ATP, additive reduces weight by eliminating those attaching features while also optimising design of the parts.”
Additionally, beneficial to the ATP is an expedited engine certification schedule. GE recently completed ATP combustor rig tests six months ahead of schedule due to the faster part production speeds allowed by additive manufacturing. For instance, the combustor liners were printed in just two days.
“A huge benefit of additive is expedited test schedules,” added Follin. “For a program like ATP, one of our big philosophical points of emphasis is getting hardware to test faster instead of spending too much time with models on a computer. By putting real hardware on test as quickly as we can, we can use the resultant data to help us design the next iteration for a better product, and we get that product much faster than if we were to use conventional manufacturing methods.”
The new 1,240SHP-rated ATP is GE’s first entry in their new family of turboprop engines aimed at Business and General Aviation aircraft in the 1,000-1,600 SHP range. Featuring an industry-best 16:1 overall pressure ratio (OPR), the engine can achieve as much as 20% lower fuel burn and 10% higher cruise power compared to competitor offerings in the same size class with 4000-6000-hour maintenance time between overhauls (MTBO) and class-leading performance retention.