Team Solves CH-53K Engine Integration Issues

Colored oil smoke indicates rotor wake and wind effects while external “tufts” adhere to the outside of the CH-53K King Stallion showing surface airflow during testing, which validated a modification mitigating exhaust gas re-ingestion.  (U.S. Navy photo)     

Industry and government engineers have mitigated an ongoing engine integration issue for the CH-53K King Stallion—the Marine Corps new heavy-lift helicopter.

This “tiger team” of experts from a variety of engineering backgrounds came together to find and optimize aircraft modifications using state-of-the-art computational modeling methodologies, risk management, flight test data and systems engineering tools.

“Bringing together the tiger team exemplifies the importance and purpose of an integrated test team,” said Col. Jack Perrin, program manager, Heavy Lift Helicopter Program Office. “It was great to see the team turn the corner for the program and produce a resolution to an ongoing problem. This was a priority for the Naval Air Systems Command, industry and the Marine Corps, and the team hit it out of the park.”

The program office oversees both the CH-53E Super Stallion, which is currently in use by the Marine Corps, and the CH-53K.

The CH-53K is the premier heavy-lift helicopter that will expand the fleet’s ability to move more material more rapidly. That power comes from three new General Electric T-408 engines, which are more powerful and more fuel-efficient than the T-64 engines currently outfitted on the CH-53E.

According to Debbie Cleavenger, assistant program manager for engineering and the program office’s chief engineer, three engines created several integration issues, including the most troublesome—exhaust gas re-ingestion (EGR).

“EGR occurs when the hot engine gasses are ingested back into the system,” Cleavenger said. “It can cause anything from increased life-cycle costs, poor engine performance and degradation, time-on-wing decreases, engine overheating and even engine stalls.”

Since April 2019, the tiger team completed more than 30 test events and evaluated 135 potential design solutions for engine integration.

“The systems constraints were significant,” Cleavenger said. “One change impacted multiple systems.”

Team members worked different root cause analyses in parallel, determining the cause and developing design models to mitigate causes for EGR. From those models, iterative flight testing resulted in a validated model to assess the most promising answer.

That model was then used to construct components for one of the test aircraft that flew a rigorous series of test flights to collect data to validate the model. The extensive set of flight test data was then condensed, analyzed and presented in December 2019 to show that the result performed as predicted and provided an overall design modification that would meet the needs for the CH-53K fleet aircraft.

All CH-53Ks built for the fleet will incorporate this production solution. Only one test aircraft has been modified to the production solution, since it would not be cost-effective or beneficial to the program to modify them all.

“This is exactly what an integrated test team is supposed to do,” Perrin said. “Bring their expertise to a project, look for resolutions in a dynamic and collaborative environment, determine the best path forward and keep this aircraft on track to the fleet.”

EGR testing was executed within the reprogrammed CH-53K program execution timeline to support Initial Operational Capability in 2021. The CH-53K is continuing toward completion of developmental test, leading to Initial Operational Test and Evaluation in 2021, followed by first fleet deployment in 2023/2024.

Victoria Falcon provides strategic communications for the Heavy Lift Helicopter Program.

CH-53K Logistics Demo Improves Maintenance for Fleet

Marines with Marine Operational Test & Evaluation Squadron (VMX) 1 load the main gearbox of the CH-53K King Stallion onto the aircraft aboard Marine Corps Air Station New River, N.C., as part of a Logistics Demonstration. (U.S. Marine Corps photo by Cpl. Ethan Pumphret)

Data collected during a recent Logistics Demonstration (LogDemo) for the CH-53K King Stallion heavy-lift helicopter is already paying dividends as the aircraft moves closer to fleet introduction for Operational Test and Evaluation in 2021.

Maintenance data collection and analysis is an ongoing part of the King Stallion program, but the LogDemo was a unique opportunity to put the CH-53K through its paces in test and development, while giving fleet personnel touch-time on the aircraft. Marine Corps participation in evaluating the integrated product support (IPS) elements is key to future readiness.

During the past 15 months, the CH-53K Supportability Test and Evaluation (ST&E) team, including industry and government partners, conducted the LogDemo with the Marine Operational Test and Evaluation Squadron (VMX) 1 maintainers at Marine Corps Air Station New River, North Carolina. The team completed more than 3,500 hours of ground test events.

“Although the window for performance is considered complete for LogDemo, we are still making opportunities to evaluate maintenance for data collection,” said Todd Winstead, CH-53K ST&E LogDemo lead.

The LogDemo kicked off an on-going process of observation, identification and analysis in the logistics process for the CH-53K, he added.

“LogDemo has helped us in early discovery of maintenance deficiencies, providing lead-time for improving product support prior to commencing operational test,” he said. “It will also increase efficiency for aircraft availability.”

“In LogDemo, we took an actual CH-53K aircraft apart and rebuilt it, documenting the process every step of the way,” said Lt. Col. Julian Rosemond, CH-53K product support lead. “The LogDemo gave our Marines advanced practical experience and improved problem-solving skills. They were able to obtain qualifications and improve their capability to perform function tests to be prepared for squadron stand-up.”

LogDemo was a win-win for all involved, he said. The team received real-time assessments by working with fleet Marines. The entire program gathered valuable data to correct and improve logistics support products that will lead to increased efficiency and accuracy in the performance of future maintenance operations.

A key to the LogDemo is the verification of data in the Interactive Electronic Technical Manual (IETM) modules using an iterative approach. The IETM is a digital manual that contains technical procedures that guide the maintainers in accurately removing and installing components; performing troubleshooting and functional tests; identifying replacement parts; and interfacing peculiar support equipment to perform tasks.

The team evaluated critical maintenance tasks while conducting verification of IETM procedures—from the use of support equipment to the specific tools used to perform maintenance. For example, during the evaluation for removing and installing a major component, Marines identified discrepancies with IETMs and steps missing to adequately perform torqueing and measuring for installing a main rotor head, thus requiring technical/engineering support to correct procedures.

“If not for LogDemo and the discovery of the improper procedures, serious damage or failure to a critical safe-for-flight component could have occurred,” Winstead said.

However, because of LogDemo, that risk was avoided and the documentation has been corrected, he said.

Though the LogDemo is now complete, the team’s work continues in providing deficiency reports and report summaries. The team is also preparing for future testing, including the CH-53K sea trials, which will occur later this year.

Written by Victoria Falcon, who provides strategic communications for the Heavy Lift Helicopter Program.