Maintenance matters

Flying Safety, August, 2002

Editor's Note: The following accounts are from actual mishaps. They have been screened to prevent the release of privileged information.

Finishing the Job -- When we do our critical maintenance actions, do we finish the job? Sometimes we take care of the major parts but forget to dean up after ourselves, or assume someone else will. We also may use workarounds that are standard practice, but should they be? Be safe and finish the entire job!

Which Way Does It Go?

An F-16 completed its scheduled 300-hour phase, and during the inspection the "A" sump lube and scavenge oil manifold line was replaced. This line is the Feed and return line for all engine oil to the Number 1 engine bearing, so it is kind of important. On the first flight after phase, the aircraft was scheduled for two sorties, with hot pit in between. Unfortunately, the pilot didn't get to complete both sorties. On the second sortie, the aircraft had problems during climbout and returned to base, where the pilot engaged the departure end cable and shut down the aircraft.

Maintenance then had to remove the engine and send it to the backshop for teardown. The engine troops found the Number 1 engine bearing had failed due to oil starvation. When the bearing failed, the engine fan lost forward support and contacted the fan stator cases and affected fan rotation. The digital engine control sensed the fan speed versus core speed relationship, and since it was out of tolerance, it automatically transferred to secondary mode. Disruption of the airflow and vibration caused the high-pressure oil line to be severed, resulting in no engine oil pressure.

The moral of the story? On the F110 engine, the lube and scavenge pump/manifold gasket is composed of soft metal and has a manifold alignment pin at each end of the gasket. This gasket is used not only on the F110 engine but on other military engines as well, and only one of the alignment holes is used on the F110 engine. T.O. 1F-16CJ-2-79JG-00-1, page 2104, contains a caution stating that misalignment of the gasket will cause oil blockage to the front frame, but only in respect to a loose, distorted or missing manifold alignment pin. Figure 2-8-2 also does not clearly identify which gasket alignment pin hole is used for the P110 engine. Do you know which way to install the gaskets on your engine? Is the tech data you use clear on how to ensure proper alignment of gaskets? If not, see your supervisor for more training or quality assurance to change the tech data.

BUFF Strut Wins, Finger Loses

A B-52 landing gear strut required the seals to be replaced, and a crew of four removed the inner cylinder from the aircraft and replaced the seals with no problems. Now the fun part starts. The crew was reinstalling the inner strut and was using an MHU-83 bomb loader to apply the pressure to compress the inner strut into the outer strut cylinder. T.O. 1B-52-2-10JG-4 calls for a 10-ton axle jack for this task, but the bomb lift has a much higher reach than the axle jack. Think of the size of a BUFF strut and how high the aircraft will be to remove the inner strut. The axle jack required by the T.O. would not reach high enough to put the inner strut back in, due to this height. To overcome this height mismatch, the unit had been using the bomb lift to provide the height and capacity to completely reinstall the inner strut. One major problem with using the bomb lift instead of the T.O.-required axle jack is that the workers can't readily tell if the strut becomes jammed during installation.

Back to the story. The workers were progressing with the reinstall, and as they were raising it into place, Worker 1 placed the strut alignment tool into position. He also placed his right thumb and index finger at the top of the alignment tool. Do you see what is going to happen next? As the strut was being compressed into the outer cylinder, it jammed (surprise., surprise!). Worker 2, who was operating the bomb lift, noticed this and stopped the bomb lift, but left pressure on the strut. The strut immediately came free and jerked upward into the outer cylinder. Unfortunately, Worker 1's finger was still in the way and the tip of the index finger was severed completely.

What's That Smell?

What could have prevented the lost fingertip? First, how about keeping your fingers and other body parts out of danger areas? Second, are you using the right tool for the job that is specified in the tech data? Third, if you are using an alternate piece of equipment, is it an approved piece of equipment? It's a fact of life in the Air Force: We all use workarounds at times to get the task at hand completed, but we need to formalize the workarounds and correct the tech data to ensure we don't damage equipment or our people.

A KC-135 was attempting to fly and after numerous maintenance problems finally got the engines started. The ground crew then noticed smoke and hydraulic fluid coming from the Number 4 engine. The crew shut it down, followed by the other engines. Troubleshooting the engine revealed that the fluid and smoke were coming from the Number 4 starter bleed air duct. Everything was inspected and found in working order. Maintenance then concluded that the fluid was residual from an earlier maintenance action.