Airmen working with the aircraft structural maintenance shop within the U.S. 92nd Maintenance Squadron (92nd MXS) (Fairchild Air Force Base, Washington, USA) recently had to repair a Boeing KC-135 Stratotanker aircraft that was heavily affected by corrosion.
Repairs at the sheet metal shop was discussed with engineers at Tinker Air Force Base, Oklahoma, because the work exceeded usual field-level repair capabilities.
“I drafted an engineering technical assistance request [ETAR] speaking directly with structural engineers at Tinker,” says Tech. Sgt. Shawn Roberge, aircraft structural maintenance section chief with the 92nd MXS.
“I developed a repair plan and forwarded it to engineers for approval, as we are not able to perform any aircraft maintenance without approved guidance,” he adds. “Writing ETARs helps prepare us for future repairs, as we can refer back to them and possibly have the repair submitted and added permanently to our technical orders.”
Guidance required the aircraft to be jacked to a no-load configuration while repairs were performed. This was done to alleviate any stresses on the airframe by using supports to take weight off of the airframe while it rests on its landing gear.
Once the aircraft was in position, a nondestructive inspection was performed using ultrasonic equipment to determine the depth of corrosion. From that point, work was completed as required and the aircraft was returned to mission-ready capability.
“The shop requests over 50 ETARs annually, as we are discovering more corrosion at the field level that must be repaired,” Roberge says. “This entire process is performed to return the aircraft to full mission-capable status as well as negating the need for a depot repair team to come here and repair it.”
With an older fleet of aircraft, there is the potential for more issues like corrosion, Airmen explain. As such, performing repairs at the home base can saves significant time. If the aircraft could not be repaired on site, an unscheduled maintenance request would have to be created to send the aircraft to the Tinker depot for repairs. The last such request lasted over a year before repairs took place.
“This was not the first time we have seen this repair,” Roberge says. “In fact, we see repairs like this almost every isochronal inspection.”
Inspections are regularly conducted every two years. In this process, the aircraft is inspected in its entirety—and any issues found are fixed by the proper maintainers.
Source: U.S. Air Force, www.mcchord.af.mil.