THE HH-60W LFT&E PROGRAM: AN UPDATE
By: Samantha Block
The HH-60W (shown in Figure 1) is the U.S. Air Force’s replacement for the aging HH-60G Pave Hawk helicopters, whose primary mission is combat search and rescue and personnel recovery. Based on the in-production UH-60M, the HH-60W has been modified to meet unique mission needs. including larger internal fuel cells, increased survivability, updated mission systems, and aerial refueling capability. This article, which is a follow-on to articles in the fall 2017 and fall 2019 issues of Aircraft Survivability, presents as overview of the HH-60W aircraft, the status of the LFT&E program, and an overview of the plan for the next year.
Due to the commonalities among the -60 Hawk fleet and the many years of relevant combat data, the Combat Rescue Helicopter (CRH) Live Fire Test and Evalutation (LFT&E) team is operating under a full-up, system-level (FUSL) waiver, approved by the Director, Operations Test and Evalution (DOT&E). Therefore, the HH-60W Alternative Test Plan LFT&E strategy focuses on new and modified components and subsystems to determine the system-level survivability (susceptibility and vulnerablity) of the aircraft as well as to assess the occupant force protection. Leveraging the combinations of exisiting LFT&E test data and combat data helps the Department of Defense (D0D) and industry to understand the challenges of balances operational needs and the state of technology/industry to continue to improve aircraft survivability.
The first flight of the HH-60W was completed on 17 May 2019 at Sikorsky’s Developmental Flight Center in West Palm Beach, FL thus kicking off the joint Sikorsky/Air Force flight test program (sees Figures 2 and 3). Flight testing will occur in phases as the aircraft hardware and software configurations are modified and new airworthiness releases and obtained.
A building block approach is being used in the refueling line testing to maximize test efficiency and understand test variable effects before conducting production-representative testing. The overarching goal of the test series is to determine the vulnerability of the HH-60W to threat-induced damage to fuel lines (including aerial refueling lines), such as leaks, fires, and starvation. Phase I LFT&E testing of the refueling lines, which was conducted to evaluate self-sealing lines leak characteriics, was completed in late 2019, giving the team actual data to inform Phase II testing.
Phase III, conducted in April 2019, was completed using an iron bird replica to evaluate the potential for sustaining dry bay fires underneath the cabin floor. Production-representative fuel transfers lines and fittings were used along with realistic threats, assessing various shotline configurations impacting fuel hoses, fittings, and structural components. Dry bay conditions were monitored using thermocouples, external standard-speed cameras, and external high-speed cameras. Any damage caused by sustained fires was documented thoroughly. The results of Phase II testing is being used to determine the need for Phase III testing, which if required, will be conducted on an HH-60L surrogate aircraft.
CABIN AND COCKPIT ARMOR
Given the expected operational use of the aircraft, the HH-60W is designed with parasitic armor in the cabin and cockpit to increase occupant force protection against realistic operational threats. Designed to afford a greater level of protection than the HH-60G, ballistic qualification of the armor system is aimed at maximizing effective coverage. The joint Air Force/Sikorsky/supplier team worked through the challenge of maximizing ballistic performance around unique features in the armor design, including quick release pucks, attachments/fittings, high-use occupant areas, and panel edges.
Qualification testing, completed in May 2019, included vibration testing for aircraft installation and ballistics, with completion of environmental testing to follow. During ballistics qualification, the team encountered a concern with excessive backface deflection and worked to evaluate the risk of significant occupant injury by using a test procedure described in body armor testing. Using a combination of test standards as a result of actual results encountered in testing is an example of the integration of the systems specification qualification and LFT&E teams. This approach creates efficiency in the overall program schedule as well as better overall occupant protection while meeting qualification standards and LFT&E standards.
LFT&E of the armor system will begin with representative coupons to determine baseline performance of the armor against operationally relevant threats using DOT&E-approved statistical analysis methodologies. The results of the coupon testing will inform testing of full panels installed on a surrogate H-60L aircraft. The results of this testing, which is planned to take place in late 2019, will be incorporated into the overall aircraft vulnerability analysis report, and then into the consolidated LFT&E report, prior to the full-rate production decision.
The HH-60W fuel cell was completely redesigned to account for the extended combat radius and increased aircraft weight (as compared to the UH-60M baseline aircraft). Qualification test activities began in late 2016, continued throughout 2017 and 2018, and were completed in early 2019. LFT&E testing of the fuel cell will begin in 2019 and will include testing to characterize the system’s performance against the combat environment in which the HH-60W is designed to operate. The system will be tested to operationally relevant threats in a production-representative installed configuration, and the results will be analyzed for incorporation into the Integrated Survivability Assessment.
The HH-60W incorporates various design upgrades intended to increase overall aircraft survivability, including an upturned exhaust system. The inclusion of this system is anticipated to change the aircraft’s infrared signature when compared to the HH-60G. A joint test that encompasses developmental test, operational test, and LFT&E objectives will be conducted to determine the aircraft’s signature in a variety of flight modes. The signature will then be analyzed against the anticipated operational environment to determine the aircraft’s posture. If required, the tactics, techniques, and procedures will be updated to reflect the changes. Once again, this joint approach provides efficiencies in the overall test program and reflects the truly integrated nature
of the CRH LFT&E team.
In 2020, the CRH LFT&E team will aim to complete all LFT&E testing and work to incorporate the results into the various analyses in support of the consolidated report, including Ballistic Vulnerability Analysis, Occupant Casualty Analysis, Integrated Survivability Analysis, and Low-Energy Laser Analysis.
ABOUT THE AUTHOR
Ms. Samantha Block is the CRH LFT&E team lead for the Air Force Life Cycle Management Center (AFLCMC/WITH) Helicopter Program Office. She is a graduate of Michigan Technological University and was commissioned through the Air Force Reserve Officers’ Training Corps program. Ms. Block was formerly an active duty contracting officer before becoming a civilian program manager and then the CRH LFT&E lead.