Maintenance matters

Flying Safety, Oct, 2003

Here we have an expensive training mission that must be flown again. For what reason? The initial writeup for the engine run came from the previous sortie when the crew wrote up that the number four engine EGT approached the overtemp limit. Maintenance performed a Jet-Cal check of the system and found the gauge to be reading 20 degrees Celsius high. To verify the system, they removed the indicator from the number one engine and checked it on the number four system during an engine run. After verifying that the number four indicator was high, they reinstalled the number one indicator back into the number one position and installed a new indicator in the number four system. A writeup was then entered into the forms that both engines required an engine run before flight. Now, T.O. 1E-8C-2-77JG-00-1 requires that an operational check should be performed using the Jet-Cal analyzer. Due to the time crunch to launch this aircraft, they asked the aircrew to perform the engine run instead of using the Jet-Cal analyzer. The crew ran the engines, and the rest is history.

Another example of where we took the shortcut to meet a deadline and didn't get anywhere. The aircraft didn't meet its mission, and we had a bunch of extra work to do after the mishap. Had the crew taken the time to perform the Jet-Cal test, as the tech data required, the mishap never would have happened. I know the Air Force is busy, but do we have to make more work for ourselves so often?

A Sparky F-15

An F-15 was prepared for a normal 1v1 basic fighter maneuver flight, and all preparations were normal. Once the pilot was onboard, things went great until the right Multi-Function Display (MFD) became unreadable. The pilot informed the ground crew, and a red-ball maintenance team was called to troubleshoot the problem. The team showed up, and after discussion with the pilot, it was determined that the MFD processor (MFDP) had failed and needed to be changed. Following the red-ball checklist, the pilot shut down the left engine and pulled all the applicable circuit breakers for the MFDP. The expeditor brought the replacement part and the ground crew went about changing the part. The next thing that happened was the pilot shutting down the engine and ground-egressed the aircraft. They had to take one of the workers to the emergency room for treatment after he received a shock from the aircraft.

How did a worker receive a shock during normal red-ball maintenance that was following the checklist? In this case, an after-the-fact inspection of the aircraft found no evidence of shorted wires on the MFDP. They did find shorted wires on the radar unit wire bundle that sits behind the MFDP. The wire bundles were chafed due to the frequent removal and installation of the MFDP. Over time, the insulation had broken down and allowed a path for 115 Volt 3 phase stray electrons to reach the MFDP when it was installed. Luckily, the maintainer was only disoriented and had to spend a couple of days on quarters.

We must always be ready for the unexpected. Here was a case where a worker could have received a life-ending shock, but we were lucky. Make sure when you are changing a black box that you take a few seconds to look around for things that aren't right...like chafed wire bundles!