NAWCAD Prototyping Instrumentation and Experimentation (PIE) Department and Atlantic Test Ranges (ATR) personnel and members of the CH-53K Integrated Test Team (ITT) traveled to the McKinley Climatic Chamber at Eglin Air Force Base (AFB), Florida, to support several months of hot- and cold-weather testing on the King Stallion heavy-lift helicopter. Aircraft testing included environmental systems as well as aircraft startup, operation, blade fold, and landing gear operation.
The extreme temperatures and simulated weather provided unique challenges for both personnel and equipment.
Barry Crocker, an ATR data engineering and analysis liaison with the ATR Telemetry Systems Branch, led ATR’s effort and visited Eglin in February 2021, to perform a site survey, evaluate requirements, and determine other ITT needs during test events scheduled for the aircraft while in the chamber.
In August, PIE and ATR personnel began working with the ITT to ring out a direct-connect option to the aircraft.
“This direct connection provided the data stream to our equipment at Eglin,” Crocker explained. “Several options were tried and we settled on cabling from the instrumentation package as the primary solution and a direct coax cable hookup from the transmitter as a backup.”
In December, Crocker from ATR, and Dairel Santos, followed later by Jason Shamberger and Gordon Thompson from PIE, traveled to Florida with members of the Sikorsky instrumentation team to begin setting up for testing the CH-53K.
Additional ATR personnel supported tests at Eglin on a rotating schedule. “Dan Coyne, Mike Kerr, Chance Pulliam, and Zach Gunn swapped out as telemetry system operators,” Crocker said. “Jonathan Boyd served as systems administrator for the first two weeks of testing to ensure computer systems were functioning properly after transport to Eglin. Tim Pearson, from ATR Test Communications, set-up the communications system between the aircraft and test control booth.”
The test aircraft arrived at Eglin on December 22, and PIE and ATR performed tests on ring-outs between the aircraft instrumentation system and a portable version of ATR’s Real-time Telemetry Processing System (RTPS) through the holidays. Testing started on January 6. Hot weather testing simulated temperatures up to 122 degrees Fahrenheit.
“Other than trying to stay away from the heat lamps set up over the aircraft and wearing gloves to keep from getting burned when swapping tapes, there were no issues,” stated Santos.
In contrast, the cold-weather testing—which took a much longer seven days and in temperatures as low as 40 degrees below zero—was much more difficult on the team and instrumentation systems.
“After I got a tour of the cold chamber, I quickly ran to the store to buy warmer clothes,” Thompson said, and joked about not packing enough cold-weather gear for Florida.
In addition to having to overcome warmth issues themselves—even with the cold-weather suits provided by Eglin to wear in the chamber—the team had to develop several workarounds to keep instrumentation systems working without any major failures.
Santos explained, “We had to keep the system running for two to three days straight to avoid cold starts at negative 40 and added a heating strip and heating pads to the recording system to keep it warm.”
Other issues included having to troubleshoot flight control computer data and remote multiplexer unit loading issues in the cold temperatures.
“It was very difficult to work with gloves on—we used portable heaters on the aircraft to keep our hands warm while troubleshooting issues, and rotated out of the chamber every ten minutes,” said Santos.
Outside of the aircraft, the team used hand warmers to wrap around two main rotor clock angle sensors to keep them operational; swapping warmers out every nine hours.
“We used the hand warmers on other hardware to keep them operational as well—GoPro cameras, Magic Mirror Tablet, TC readers, etc.,” he said.
In addition to keeping equipment warm enough to operate, the team had to carefully step around Ethernet and power cords on the ground to avoid cracking and breaking the cords in the extreme cold. Keeping gadgets warm led to other unexpected problems.
“Laptops, cameras, and other support equipment became soaked with condensation once it left the cold environment and went back to the ambient building temperature,” Thompson said, “and fluctuations in temperatures caused many of the adhesives used to hold sensors to become unglued.”
During the last few days of testing at Eglin, the team also provided aircraft re-positioning support when testing in high winds at 30 to 40 knots.
“We had to disconnect, reconnect, and re-route all telemetry, Ethernet, and power supply cables—about 200 feet of cables each time they repositioned the aircraft,” said Santos.
Collectively, the hot, cold, and wind testing was completed with no major instrumentation failures and the CH-53K was ferried back to Patuxent River. Successful test results could lead to its participation in a cold-weather event planned for this winter.
“With PIE-ART instrumentation and mobile equipment in place, we not only provided real-time data observation and analysis but also an avenue for rapid post-test data evaluation,” Crocker said. “This allowed the test team to plan and progress through various test events faster. We had zero lost testing days or events due to our instrumentation or RTPS system for the duration of the deployment.”
To anyone who plans to endure the McKinley Climatic Chamber or participate in future cold-weather events, Thompson summed it up well, when he said, “I have a greater appreciation for how cold, cold can actually be.”