As the Rotor Turns.
With his flashlight and checklist in hand, he climbed aboard the aircraft to begin his inspection. Immediately, a peculiar color screamed at him: One of the main rotor blade indicators was red instead of the familiar yellow. This was an indication that the blade's nitrogen pressure was below a serviceable threshold. This was not entirely uncommon, and usually was the result of a leaky fitting. By the end of his shift, Airman First Class Hatch had completed his inspection, replaced the indicator's fitting, serviced the blade, and successfully prepped the aircraft for the next day's flight.
Two weeks later, A1C Hatch experienced an eerie sense of deja-vu as he ascended the aircraft and again was greeted by a red blade indicator. He confirmed it was the same blade, and notified his supervisor of the recurring problem. A1C Hatch discussed the situation with SrA Eddie Cano, and the two agreed that the problem could be caused by a slow leak in the indicator. They replaced the component and successfully serviced the blade. As an extra precaution, they performed a final check at the end of their shift, to ensure the blade pressure was holding steady.
The next night, as A1C Hatch pushed his toolbox to the aircraft, he had a surreal premonition of what he would discover. He grabbed his flashlight from the toolbox and shined it at the bright red blade indicator. At this point, SrA Cano and A1C Hatch both agreed that something was awry, and it wasn't as simple as a leaky indicator. Clearly the system was incapable of holding a steady pressure, despite the servicing equipment stating otherwise. They removed the blade for further inspection in an attempt to save the asset and the next day's flights.
With the blade now on a maintenance stand, several maintainers examined the entire blade for any indication of a leak. Under the scrutiny of seasoned maintainers, the blade appeared to be serviceable. The indicator held yellow, with no visible indication of structural damage.
During the next shift, SSgt Lucas Brogdon was assigned 3 key tasks to complete. First, he had to install the new blade. Second, he had to perform a track-and-balance check. Finally, he had to figure out what was wrong with the removed blade. As a Flying Crew Chief, his duties required him to fly with the aircraft to perform in-flight maintenance. Fortunately, the installation and functional checks for the new blade went smoothly, and the aircraft successfully flew for the night's training.
The next day, he was able to dedicate himself fully to working on the suspect blade. Just as before, the indicator still showed the blade to be serviceable. He covered the blade with soapy water, and led a team of Airmen in examining the blade's surface closely. If it had a slow leak, the released nitrogen would form small bubbles that would reveal structural damage; however, after an hour, the blade still showed no indication of a leak.
Something was occurring inflight that was causing this blade to leak.
SSgt Brogdon realized that the only difference between the blade sitting on the maintenance stand and the blade installed on the aircraft was its position. As the rotors of a helicopter begin to turn, centrifugal force raises the blades' tips into a level position. Inputs from the flight controls further alter the blades' angle, and their tips are raised or lowered as the aircraft ascends or descends. It was possible that the blade in question was leaking while in a flight position, instead of in its normal resting state.
Each main rotor blade on an H-60 is 26 feet long, and weighs 250 lbs. With a team of 12, SSgt Brogdon lifted the blade and placed it onto 2 saw-horses. Again, he covered the surface with soapy water, and manipulated the assembly into positions simulating flight. With the blade's tip raised, SrA Louis Severson spotted a small cluster of bubbles forming near the blade's cuff, a location not easy to inspect when the blade is installed. They removed the protective paint and primer to reveal a severe crack.
The discovery of the cracked blade drove a joint investigation by Army and Air Force Engineers. In the end, 3 other suspect blades were linked to potential manufacturing defects.
The creative and adaptive thinking of the Crew Chiefs of the 55th Helicopter Maintenance Unit undoubtedly prevented a catastrophic mishap. More importantly, it saved lives. Their thorough inspection and commitment to excellence restored the aircraft's safety of flight with positive fleet-wide and DoD impact. Their exemplary efforts also resulted in their being recognized by Air Combat Command as the Crew Chief Safety Award winners for the First Quarter of FY21.
BY SMSGT JOHN B. KNEEN