Maintenance squadron phase and letter checks keep aircraft mission ready Published July 5, 2022 By Staff Sgt. Darius Sostre-Miroir, 920th Rescue Wing Public Affairs 920th Rescue Wing PATRICK SPACE FORCE BASE, Fla. -- The aircraft that carry out the 920th Rescue Wing’s mission of rescuing isolated personnel take on various levels of wear and tear and after hundreds of hours flying they require intensive maintenance known as letter checks, or phases, which the 920th Maintenance Squadron provides throughout the fiscal year. The 920th MXS is responsible for back shop and heavy maintenance on the wing’s six C-130J Combat King II aircraft and ten HH-60G Pave Hawk helicopters. “Keeping our aircraft well maintained improves the overall health of the fleet. We look for and fix any wear and tear so we can minimize the risk of any failing components, keep our crews’ safe, and successfully complete the mission,” said Senior Master Sgt. David Carden, 920th MXS flight chief and production superintendent. To keep the C-130J Combat King II operational the 920th MXS performs letter checks, which are routine inspections of various levels. Letter checks are broken down in four categories A, B, C, and D. These checks go from a basic inspection, (A), to the much longer more intensive check, (D), where the aircraft is stripped down, thoroughly examined, and then restored at the depot facility. Each letter check is 270 days apart with an A check in-between each new letter grade. Similarly, the HH-60G Pave Hawk has a phase inspection conducted on an hourly interval. A phase inspection will begin at 50 hours flown and be much like an A check for the HC-130J. After that, it increases to a 150, 300, and finally a 600-hour phase. During each advanced phase they incorporate all previous phases into the new one as well. A 600-hour phase will also see the Pave Hawk stripped, inspected, and reassembled. Letter checks and phases for the aircraft are detailed inspections with many items on them to review. Engines are thoroughly inspected for discrepancies. Aircraft inner floors are removed which allows for corrosion inspection and repair. Every part from the furthest screw to the most inner wire is looked over, tested, and rebuilt or replaced as needed. Letter checks are effective at combating corrosion which is a common problem for any aircraft that fly over the ocean. Sea breezes blow salt in the air which slowly corrodes the aircraft’s frame or contributes to failure of electronic components. This negatively affects the performance and reliability of the aircraft so maintenance personnel clean and repair any defective parts throughout the process. “The end goal of these inspections is to have a fully mission capable aircraft ready to fly. An example of this is during a recent real-world rescue, the HC-130J used to refuel the Pave Hawks was on its first flight after a letter check. It completed the lifesaving mission with no issues at all,” said Colonel George Cole, 920th Maintenance Group commander. Doing the final check on both types of aircraft effectively resets it back to its original state and allows it to continue another long cycle of use for missions. Every aircraft is meticulously maintained through these checks so they are flight ready the moment they are completed. “The maintainers are the backbone of how the Air Force stays in the air. They are needed to maintain all flying missions. It takes time to become an experienced maintainer, and the people here at the 920th MXS are phenomenal at their job,” said Senior Master Sgt. Carden.