Fatigue, human error, bad management?

Recently the National Transportation Safety Board (NTSB) issued a statement regarding the December 2011 air tour helicopter crash near Las Vegas.

The NTSB states the crash was the result of the operator’s “improper reuse of a degraded self-locking nut in the servo control input rod and the improper or non-use of a split pin to secure the degraded nut, in addition to an inadequate post-maintenance inspection. Contributing to the improper (or lack of) split pin installation was the mechanic’s fatigue and lack of clearly delineated steps to follow on a ‘work card’ or ‘checklist.’ The inspector’s fatigue and lack of a work card or checklist clearly laying out the inspection steps to follow contributed to an inadequate post-maintenance inspection.”

There are several disturbing parts in this statement. First and foremost, of course, is the loss of life caused by human error. Secondly, the two statements that come from basic hardware and maintenance training at every A&P school in the country: A fiber lock nut is never to be reused. It loses its properties to stay locked when reusing it. It was also castellated, so a cotter pin is used as a secondary method to secure it. How is that forgotten? Fatigue was definitely an issue, as these were obvious errors.

“This investigation is a potent reminder that what happens in the maintenance hangar is just as important for safety as what happens in the air,” said NTSB Chairman Deborah A. P. Hersman.

This is an understatement. If you need a reminder of this, please do not fly! Whether you realize it or not, you trust your maintenance professional with your life and the lives of your loved ones. The majority of maintenance professionals know this as well, which is why I would like to ask management some questions that the NTSB didn’t.

Why was a castellated fiber lock nut reused? For efficiency in getting the job done because of pressure that it must fly? Because a castellated fiber lock nut for this installation is expensive? They did not have a new nut in inventory? These questions are not entirely the mechanic’s fault based on the answers we do not have. It could be a work environment set up by the company, down to the managers and supervisors and flows out to the employee. Those of us who have been around a while have heard these stories. It is unacceptable on two parts.

As an aviation maintenance professional, it needed to be recognized that the aircraft was grounded until a new nut was available, if it wasn’t — no matter the cost. The aircraft should have been grounded. Secondly, the possible work environment that sets up this scenario is unacceptable. The lack of understanding of fatigue on all parts, management and technician, needed to be addressed. Ask your shop how this is addressed. If the work environment was possibly an unsafe one based on standard procedures set by management, the technicians should address it no matter what the cost, even job loss, as the costs mentioned here do not even come close to the costs of the loss of life in a crash.

As aviation maintenance professionals we do not need to be reminded that what happens in the maintenance hangar is as important for safety as what happens in the air. In the last decade maintenance-related fatalities were 5% of all fatal accidents. Still too high, which is why we work on it continually.

One thing that may help is the realization by everyone else in our industry, including management, that what happens in the maintenance hangar is important to safety. Step back and look at the work environment.

For more information: PAMA.org


  1. Ray Klein says

    Bravo Tim an 40,000 hrs. accident free! This is a terrible, avoidable loss of life and equipment. non reuse of friction locknuts on aircraft is A/P 101. I know this enviroment is hurried and thankless. But integrity must prevail.

  2. says

    As a recently retired construction crane operator with a lifelong interest in aviation, I am finally able to devote time to my interest in flying. On the safety issue addressed in the subject article by Dale Forton, it is my beleif that tremendous safety increases could be achieved, were it not for the often times negative work site influences. There is always the need to impress upper management or the bean counters or whoever and if this can be done by ignoreing standards that we know can and will eventually prove problamatic, then the price paid is reduced safety and loss of human life. The paralelle safety standard that must be maintained in construction crane operation and aviation has always been interesting to me and I have benefited in my crane operations by studying aviation safety and applying those standards whenever possible in crane operations. I like to beleive that the far more rigerous aviation standard was a large influencing factor in my 40,000 hours of accident free hoisting experience.

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