Turbine Technology: The CF34 Turns 20

Oct. 26, 2012
A model for reliability with 10 versions to date.

This year marks the 20th anniversary for GE Aviation’s CF34 family of engines. The military version TF34 which powers the U.S. Air Force A-10 and U.S. Navy S-3A, was a key factor in developing engines for the regional jet market.

There have been 10 versions of the CF34 to date, beginning with the CF34-1 that was used on Bombardier CL-601-1A through the CF34-10E used on the Embraer E-195. The first commercial -3 model was installed on the CRJ 100 and CRJ 200 aircraft in 1992. This engine family has been on the GE Aviation’s best seller list for a long time.

On May 25, 2010, GE announced it had delivered the 5,000th CF34 engine. The CF34 engine has evolved over the decades with design changes and modifications to increase thrust, reduce parts, and strengthen the core engine resulting in improved performance and lower maintenance costs. The durability and reliability of these engines is incredible -- with more than 80 million flight-hours and 65 million cycles completed, the dispatch reliably remains at 99.95 percent. 

It is interesting to compare some of the specifications of the various models. The CF34-3 is 103 inches long, has diameter of 49 inches, and a dry weight around 1,650 pounds. The core engine has a fan and 20 combined compressor and turbine stages. It has a power-to-weight ratio of 5.6:1 and thrust at sea level is 9,200 pound-feet. This engine would typically power aircraft like the Bombardier CL-601. The latest model, CF34-10, is only 90 inches long, has a larger diameter of 57 inches, and a dry weight of 3,700 pounds. The core engine has a fan with three additional “booster stages” and only 14 total stages for the compressor and turbine.

The new CF34-10E has a higher thrust rating of 20, 000 pound-feet, and lower fuel burn and maintenance cost. This radical increase in thrust was produced by a single-stage high-pressure turbine, advanced wide chord fan blades, and advanced 3-D aero compressor and turbine airfoils. The CF34-10E engine powers the Embraer E190 and 195, and the new Embraer Lineage 1000 business jet that entered service in mid-2009.  

Outlook for the CF34 family

The utility of the smaller 50-70 seat regional jet in some North American markets is being questioned. According to Judd Tressler, GE Aviation’s director for CF34-3 Commercial Engines, “There will be fewer numbers of those aircraft in North America but they won’t all go away, just move to other markets with demand for that seat capacity.”

Tressler was asked if the large numbers of CF34 -3 engines that have been in service for the last 10 years are being pulled and sent to the shop for overhauls. “There was a large peak in aircraft production about eight years ago. Those engines reached their first shop visit over the last few years and there was a wave of shop visits.

"The GE overhaul facilities are seeing the back side of that peak now so they are working with operators to develop different services like shop visit optimization programs, fixed cost by the hour, and other creative ways to reduce maintenance cost.” 

MROs and GE branded service 

With more than 5, 600 CF34 engines in service, GE must have a global network of service providers operating on a 7 by 24 schedule, providing spare leasing, major overhaul of engines and components, and a ready supply of parts. Major engine overhaul is completed at GE's Strother facility near Arkansas City, KS, but GE has a network of service providers located around the globe. 

Tom Hoferer, GE Aviation’s director for CF34 Engine Services, gives some insight to GE’s vetting process. “When selecting an MRO partner, we look for one that has made the necessary capital investment to be in business for the long term. The location of their operations is very important because we must ensure we have regional service coverage for our customers. They must have FAA or country-equivalent certifications and demonstrate an allegiance to the OEM so the MRO is perceived as an extension of GE services.

"We are looking to add one service facility in Brazil and one in China sometime over the next five years. However, we are being very aggressive in the business jet market. We have 21 authorized service centers in the U.S. and are looking to grow our global centers with another 17. We will be providing mostly level 1 line maintenance at these centers. Other services are provided in a GE branded service facility or GE-authorized shop.” 

MTU Maintenance Berlin-Brandenburg

One of those service providers for the repair and overhaul of the CF34 is the German company MTU Maintenance Berlin-Brandenburg, a wholly owned affiliate of MTU Aero Engines, Germany’s leading engine manufacturer and a public listed company. 

GE Aviation and MTU have been cooperating closely both in the manufacturing of several engine types like the CF6, the GP7000, and the GENx and in the after sales market. This decision was based on MTU's ability to offer especially to European CF34 customer’s facilities, technology and services that meet GE’s quality and customer service standards. 

MTU Maintenance Berlin-Brandenburg was the first independent MRO provider that could service all models of the CF34 family of engines. MTU offers a vast array of services, among which are modifications, retrofitting, repair, and overhaul, on-wing services as well as engine condition monitoring, spare engine leasing, and AOG support.

MTU Maintenance Berlin-Brandenburg has been a GE-branded service provider since 2001 and has extended its agreement until 2022. The company also has signed a component repair development agreement with GE. There are about 650 employees in the facilities located south of Berlin.

Typically, their technicians complete a three-year dual apprentice program and are certified by EASA. According to Nils Fenske, director of sales and marketing CF34, this intensive training has a big impact on the quality, capacity, and turn-around times. Production figures given by Fenske were impressive.

So far, they have overhauled up to 130 CF 34 engines per year with a breakdown of 80 -3s, 25 -8s, and 25 -10s. Depending on the workload, the technicians can overhaul the -3 in about 45 to 55 days and the -8 in about 55 to 65 days. The time for overhaul on the -10 varies due to the fact that the upgrades in the scope of work require more collaboration and communication with the GE staff. 

I asked Fenske to give me his opinion as to why the CF34 family of engines is so reliable and durable. He suggests that it is because the engine has a very robust compressor, and hot section engines are usually pulled because of the life limits of parts and not because of wear and damage. When questioned about damage, he says that “FOD damage is usually not a significant issue and can be fixed with top case repairs rather than pulling the engine.” In fact the MTU motto is “repair beats replacement.”   

It appears that the CF34 family has a bright future and long life ahead. The CF34-10E model has been performing well and developing an excellent record with 1,100 in service and 7 million hours flown. So what is next for the CF34 family? The GE interview members say, “We will continue improving the CF34-10 engines,” however, like all things, change in aviation is inevitable, expected and necessary.

As Will Rogers, my favorite philosopher said, “You may be on the right track but you will get run over if you just sit there!” GE Aviation seems to be on the right track and not just sitting on its legacy because there is a new player in town.

Mary Hussey, GE Aviation’s marketing manager for Small Commercial Engines, says the GE Passport “Next Generation” engine will soon be powering the Bombardier Global 7000 and 8000, and GE has a technology development program, called the NG34, to mature technology for the next-generation CF34 engine. What is next for the CF34 product line? Maybe time and customers will tell. Whatever occurs, our aviation techs will have plenty of interesting engine work to perform.

About the Author

Charles Chandler | Field Editor

Field Editor Charles Chandler has a Masters of Science Degree in Adult and Occupational Education with a major in Human Resources Development. He began his aviation career as a junior mechanic for American Airlines and retired after 27 years of service. After leaving American he held both line and staff positions in six other major companies. His positions with those companies included curriculum development specialist, manager and director for organizational development, management and leadership development, and maintenance training operations departments.