Eurocopter Maintenance Failure:

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Dickemore 1 Maya Dickemore PILT 1010 AM 15 September 2013 NTSB Report Eurocopter Maintenance Failure: Lack of sufficient sleep, a sudden change in work hours, and working without clearly written work

1 Dickemore 1 Maya Dickemore PILT 1010 AM 15 September 2013 NTSB Report Eurocopter Maintenance Failure: Lack of sufficient sleep, a sudden change in work hours, and working without clearly written work instructions can all lead to missteps at work. Employees can often go to work lacking sleep. Training on how to identify hazardous thoughts and behaviors can be life-saving for everyone involved. If employees do not receive this training they are less equipped to manage these particular risk factors. When added together, multiplied by two people and combined with the world of aviation, the consequences of these conditions can be catastrophic. Unfortunately, in 2011 they were just that for a sightseeing helicopter tour in Nevada. Errors made by a fatigued maintenance crew rendered the aircraft uncontrollable and caused it to crash in the mountains near Las Vegas, Nevada. All five of the people onboard perished. What Happened? On December 7 th 2011 a Eurocopter AS350-B2 was conducting a sightseeing tour east of Las Vegas in the Hoover Dam area. It was proceeding along its prescribed route (see figure 1) when the accident happened. The helicopter experienced a series of uncontrolled maneuvers before impact with the mountains 14 miles east of Las Vegas. According to the Aircraft Accident Report from the National Transportation Safety Board (NTSB), improper use of a degraded self-locking nut was the main cause. (Board, The purpose of the self-locking nut was to hold the bolt in place that connected the fore/aft directional input rod to the main rotor. The split pin that is used to hold the self-locking nut onto the bolt was also missing. The hydraulic belt was found to be improperly installed during the investigation, as well. With the input rod no longer connected to the main rotor the helicopter could not be controlled. (Board,

2 Dickemore 2 Figure 1. The flight path diagram shows that the prescribed tour route was followed until the sudden malfunction occurred. The flight path immediately preceding impact was short and erratic. The malfunction would have been completely unexpected by the pilot. Source: (Board, Identified Safety Issues There was a definite chain of safety errors leading up to this accident. The first one identified by the investigation was the improper use of a worn out self-locking nut. Even though there is readily available guidance on the reuse of self-locking nuts, the maintenance personnel were not following it. (Smith) In the NTSB report it was written Sundance Helicopters maintenance personnel were reusing nuts that did not meet the criteria specified by Eurocopter and FAA guidance. (Board, The second error occurred when the inspector signed off on the repair without noticing the discrepancies. It may seem that all of the blame should fall on the maintenance personnel at first, but more in depth research showed that fatigue and training deficiency may have been contributing factors. Why Would They Make Those Mistakes? If one safety error can place an aircraft and its crew in danger then errors by multiple personnel just amplifies the possibilities for disaster to strike. It was found that the two maintenance personnel connected to this repair were fatigued at work. Both the mechanic and inspector were required to work an earlier than normal shift. Even though the mechanic went to bed earlier than usual, he was unable to sleep much the night before his December 6 th shift. His shift started six hours early, lasted nearly 11 hours and he only had 5 hours of sleep the preceding night. The inspector was able to get seven hours of sleep, but his shift also started six hours early. The inspector worked a 14 hour shift the day the maintenance was done on the Eurocopter. (Board, The NTSB report indicated that these conditions were the causes of the fatigue experienced by the maintenance personnel. According to the NTSB, fatigue has several adverse effects on employees. Fatigue causes difficulty sustaining attention, memory errors, and lapses in performance. PhD Anne Rogers explains that The effects of sleep loss are insidious and until severe, are not usually recognized by the sleepdeprived individual. (Rogers) She sites from various studies that cognitive problems, mood alterations, reduced job performance, reduced motivation, increased safety risks, and physiological changes can all be related to insufficient sleep. She also mentions that rotating shifts can contribute to the problems associated with insufficient sleep. (Rogers) The maintainers in question for this accident were experiencing altered work shifts, lack of sleep, and long work hours while they were required to perform the maintenance on the Eurocopter s main rotor input rod and belt. A clear mind is not all that is required for an employee to perform to the demanding standards of the aviation industry. In order for an aviation maintenance technician to perform his or her job functions correctly they need to have clear directions for every procedure. Even the most skilled and alert maintainer can accidentally miss a step. The NTSB investigation found that the inspection steps

Dickemore 3 were not clearly stated in the work instructions. There was a reference to more detailed instructions, but there was no requirement for an inspector to sign off the individual steps.

3 Dickemore 3 were not clearly stated in the work instructions. There was a reference to more detailed instructions, but there was no requirement for an inspector to sign off the individual steps. The investigation explains that Using documentation that clearly delineates the steps to be performed and critical areas to be inspected to support the maintenance and inspection task is one way to mitigate these factors. (Board, Work cards provide individual steps for each requirement and are a great tool to keep the technician on track if they get distracted. If the technician and the inspector were fatigued why would they not be more careful to check their work more thoroughly or get a second opinion? Did They Not Know Fatigue is a Problem? Sundance Helicopters, Inc. is a Part 135 operator. This means they fall into the category of commuter and on demand operations and rules. They are not required to provide human factors training. (Transportation) Human factors training helps employees recognize human induced hazards, like working while fatigued. Within my own circle of influence most of my coworkers, colleagues, family, and friends work with sleep insufficiency at least occasionally. Since it is a somewhat common occurrence, recognizing it as detrimental may not be an obvious observation. People can get used to being fatigued so it becomes a regular aspect of their life. They need to learn how to recognize and avoid fatigue, as well as, monitor its effects on their performance. (Board, To bring the dangers and symptoms to the forefront of a technician s conscious helps reduce the chance of mistakes like the ones that lead to the Eurocopter s malfunction and subsequent crash into the mountain terrain. Something Does Not Make Sense Having been an aviation maintenance technician for over six years and an aircraft hydraulic component manufacturer for another four there is an item that disturbs me. My education and experience taught me that self-locking nuts do not get reused. Since the report specified that there was a missing split pin, I know that this was a castellated self-locking nut. Castellated nuts always require a split pin that is the whole point of that style of nut. See Figure 2 for an example of a split pin. I realize that fatigue could most definitely cause the technician to forget the split pin and the inspector to overlook that on inspection. What would make someone reuse a self-locking nut instead of discarding it during disassembly? It was mentioned in the NTSB Aircraft Accident Report that Sundance Helicopters was not following Eurocopter and FAA self-locking nut reuse guidance, which led to the repeated improper reuse of degraded nuts on its helicopters. (Board,

Dickemore 4 Figure 2. Here you can see an example of a split pin. It gets pushed through the bolt and self-locking nut then each half is bent in opposite directions. Source: https://www.google.

4 Dickemore 4 Figure 2. Here you can see an example of a split pin. It gets pushed through the bolt and self-locking nut then each half is bent in opposite directions. Source: PloM&tbnid=PRPIa6Et1pyDyM:&ved=0CAQQjB0&url=http%3A%2F%2Fwww.applegate.co.uk%2Flistings%2Fstock%2Fs3i-ltd-stainless-steel- solutions%2fselected-items-index page1.html&ei=xys_uun2f6wvial_u4cabw&bvm=bv ,d.cge&psig=afqjcnewduq3ygnyjvwcgy9ca5sqps5vg&ust= If a technician is used to tossing out certain items during the disassembly process they would be much more likely to do the same even while fatigued. This would force them into using or ordering a new one for reassembly. When working under these conditions a person subconsciously depends on their habits to get them through. A self locking nut is a critical item and the point of these nuts is that they do not need a secondary locking device like lock wire, split pins, or a chemical locking compound under normal use conditions. Therefore, they should not be able to be tightened by hand. Note the wear on the self-locking nuts from other Sundance Helicopters Inc. aircraft in Figure 3. Aircraft use dual locking devices on critical components to ensure safety. All of this I learned while working long hours and sleeping less than I should have for extended periods of time. Observing my coworkers who were working at the same fatigue rate as me I noticed that the habits formed during training and early experience helped them maintain safe work practices. After working closely with your fellow team members a level of trust is developed. Figure 3. On the red condemned tags are worn and unusable bolts, washers, and nuts. To the right are a new bolt and nuts. You can clearly see that the old hardware shows unmistakable wear. Source: (Board, What Does it All Mean to me? When I became a certifier signing off other people s work I developed certain habits. There were maintainers who I watched closely and I was extra cautious when I certified their tasks. There were those that I had a very high level of trust in and I would only check the minimum requirements. How did

5 Dickemore 5 that nut get reused? I can only answer that for some reason that particular technician could have been in the habit of reusing self-locking nuts; and the inspector could have placed too much trust in the technician to do the job right. He was not thorough enough before he signed off the task. This is when work cards would have been a saving grace. Why were they not used? Work cards are not required for Part 135 operations, so the management is not obligated to provide them. It would be prudent, however, for a company with an overworked staff to install these extra measures to be safe. A manager or owner familiar with human factors in the workplace could see the risk factors of a fatigued workforce and implement the use of work cards. If the fatigue of overworked employees was noticed and the work cards were implemented then the human factors training for technicians may be the next logical step. It would help if shift work policies were revisited to make sure the workers are rested and alert while performing such critical tasks. The human factors training would help them identify possible risk factors. The employees would be better equipped to identify the risks involved with their own physical, mental, and behavioral conditions. These steps outline a logical progression to a more safe and correct aviation maintenance environment. There were at least three missteps leading to the fatal Sundance Helicopters, Inc. crash: improper maintenance, improper inspection, and lack of proper human factors training. All of them were preventable and all of them have a logical solution. All that was needed was some observation and foresight on the part of the management and maintenance team at the maintenance facility. Works Cited Board, National Transportation Safety. 7 December PDF Report. 15 September Powerpoint presentation. 15 September Rogers, Ann E. Bookshelf. April Handbook. 15 September < Smith, Murray E. "Self Locking Nuts on Bolts Subject to Rotation." Advisory Circular. Federal Aviation Administration, 24 August Document. Transportation, U.S. Department of. "14 CFR Subchapter G Part 135." 2013 FARAIM. Newcastle, Washington: Aviation Supplies & Academics, Inc, Regulation.

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IMPROVING SAFETY: FATIGUE RISK MANAGEMENT

IMPROVING SAFETY: FATIGUE RISK MANAGEMENT Prof Philippa Gander NZAAA Conference 25/7/2017 Outline What is fatigue? Is fatigue a safety issue in general aviation? Causes of fatigue in general aviation Managing