PATRICK SPACE FORCE BASE, Fla. -- Part of the maintenance group’s routine cycle of in-depth inspections that ensure aircraft remain safe and airworthy are letter checks of HC-130J Combat King II aircraft and the 920th Maintenance Squadron recently executed one here to keep the wing’s rescue aircraft mission capable.
A letter check is a scheduled inspection where maintainers tow the aircraft into a hangar, remove panels, examine critical systems, and repair or replace components before returning it to the flight line.
“During a letter check, we get deep into the aircraft to really see what’s going on. It’s our chance to break things down, find issues that wouldn’t normally be spotted on the flight line, and make sure everything is corrected before the aircraft goes back to flying missions,’ said MSgt. Matthew White, 920th Maintenance Squadron Isochronal Inspections dock chief.
The Air Force’s letter check system is divided into four levels: A, B, C, and D. The A check is the simplest, taking three to five days. The B check, currently being performed by the 920th MXS, is more extensive and can take 30 to 35 days. The C check is even more detailed, often lasting up to 40 days. Finally, the D check is the most comprehensive. The first D check is accomplished by the unit, but the following ones are then performed at a depot facility, where the aircraft is taken apart down to its wings, tail and ramp for full rework.
Each check occurs approximately every 270 days, alternating between A, B, C, and D on a cycle. While the 920th MXS provides the bulk of the maintenance specialists to perform the inspections, crew chiefs from the 720th Aircraft Maintenance Squadron also support. Additional manpower from 920th MXS and 720th AMXS can also come from sheet metal, fuels, hydraulics, avionics, and engine shops, depending on the discrepancies found.
The inspection process can bring up issues that cannot be detected during routine flight line checks. For example, corrosion and cracks hidden beneath panels can threaten structural integrity or flight control systems if left uncorrected.
“It’s very important because we get into the weeds when we take things apart and really examine them. We find problems and cracks that aren’t normally checked during daily routines. Catching and fixing those early keeps our aircraft safe and ready to support the rescue mission,” said White.
Once the inspection is complete and all discrepancies are repaired the aircraft is returned to the flight line in a flightworthy condition; ready to support the wing’s combat search and rescue mission.
The 920th MXS is the largest squadron within the maintenance group. It provides back of-house maintenance support for both the HH-60G/W Pave Hawk helicopters and the HC-130J Combat King II. Fabrication, aerospace ground equipment, avionics, accessories, structural repair, HH-60 phase, and HC-130J letter check inspections are among the many tasks the squadron is responsible for.
The 920th Rescue Wing is Air Force Reserve Command’s only combat search and rescue wing, whose mission is to plan, lead and conduct military rescue operations to deny competitors and adversaries the exploitation of isolated personnel.