What if

Flying Safety, August, 2003 by Jeff Moening

This issue is mainly about aircraft maintenance and mistakes we have made in the past that have caused mishaps. Now, is every mishap preventable? Yes, it's possible. Can we maintain the number of aircraft we have in the USAF and not have accidents due to faulty maintenance? Yes, if we train our people correctly, give them the tools needed to perform safe quality maintenance and provide quality supervision. Hindsight is 20/20, and it's easy to sit in an office and second-guess a mishap based on accident investigations. But we need to learn from others mistakes, and that is the purpose of this article. Let's look at a few accidents and see what could have happened if steps had been taken to stop the chain of events or different choices had been made.

At a depot, two workers were tasked to remove the ball screw and sprocket assembly from a C-5 landing gear. A common task at the depot. The workers were working overtime, and on the day of the mishap, the gear was disassembled to a point where the main outer cylinder was ready to be removed. Like all things mechanical, this strut had become attached, and many attempts to remove the cylinder had failed. The strut was stuck. This caused the workers to deviate from procedure and remove the sprocket and ball screw before removing the main outer cylinder.

The two ball screws on the gear are removed one at a time and they use a padded four-inch stand to support the ball screw while they lower the disassembly stand. This, in turn, lowers the ball screw to the padded stand, preventing the ball screw from contacting the concrete floor, and holds it in place while the final bolts are removed. When the bolts are removed the disassembly stand is raised, allowing the ball screw and sprocket to slide out of the yoke. A worker positioned on the floor holds the ball screw and sprocket assembly upright and guides it out of the yoke until clear of the stand.

Because the main outer cylinder had not been removed, the task was more difficult and workers could not lower the ball screw down to the floor as normal; it was six to eight inches above the padded four-inch stand. The two workers were positioned on the floor, and a third worker was watching. The two workers removed the last two bolts holding the ball screw and sprocket assembly, and it, too, was jammed and would not release. One of the workers used a drift punch and three-pound steel hammer to hammer on the top of the ball screw to loosen it. After it had moved about an inch, the bearings had moved past the landings and the sprocket assembly started to turn. The worker not hammering on the strut reached up to stop the sprocket, the ball screw let go and he suffered an injury to his hand, costing the government $250,000 and lost job time while the individual received treatment.

"What If" time. What if the workers had made the choice to take the steps to remove the main outer cylinder first instead of pressing on with the ball screw? What if, seeing as how they were using a workaround, they had created another workaround to allow the padded four-inch stand to cover the gap made by the main cylinder still being installed? What if the third worker, who was overseeing the operation, saw the dangers and stopped the task until the risk could have been mitigated? ORM is out there, and it works great when you have to deviate from normal procedures. The workers were trained on the task and were trying to get the job done. What if one of them had stopped the task until they could have better ensured their own safety? What would you have done differently if this were you performing the task?

Here is another example of a past mishap. An F-15E was traveling cross-country for an air show. At the air show location, the travel pods were downloaded and the aircraft performed the show. The next day, the travel pods were uploaded and the aircraft took off for the next location. During the flight, the flight lead did a battle damage check on the mishap aircraft and found the front lug on the right travel pod had released and the pod was turned 90 degrees. The pod lost the front and back ends, and they struck the aircraft as they departed. The aircraft then landed uneventfully.

Now, the hooks for the pod can be in one of three positions--full open, full closed, or intermediate. Post-mission inspection of the aircraft showed the hooks for the right pod to be in the intermediate position. This would hold a store and it would appear to be closed, but the over center feature has not been reached. In this condition, air loads may exceed the holding strength of the hooks. The front hook, the one that came open, passed the 150-pound release test as required by the tech data.

The main cause of this $125,400 mishap can't be told here, but you can get the report from the safety office. I'm sure you can guess why the front lug let go inflight. Time to "What If." What if the crew chief and pilot had performed better preflights to ensure the pod's integrity? Many of the unit pilots thought the weapons security requirements didn't apply to travel pods. What if the travel pods had stayed on the aircraft for the air show flyby and were not removed? The aircraft configuration had changed while at the air show, so the crew chief was unprepared for the last-minute change. Since he didn't know of the change, he did not have the proper T.O. with him on the TDY. What if the crew chief had told the aircrew that he couldn't remove the travel pod, since he had no tech data for the task? Could the crew have completed their mission as, planned? If you don't have the T.O. for the task, don t perform the task. If you are going to change procedures, make sure everyone can adapt to your changes. Have the guts to stand up and do what s right.