Maintenance and Certification

Maintenance and Certification

Sharing Best Practices—Managing the Risk of Maintenance Error

by Alan Hobbs, Ph.D., Australian Transport Safety Bureau

The following is an excerpt from “An Overview of Human Factors in Aviation Maintenance” in the Aviation Research and Analysis ReportAR-2008-055, which is published by the Australian Transport Safety Bureau. It is reprinted with permission. To read the complete report, visit

Organisational influences on maintenance error
Although maintenance occurrences usually involve errors made by technicians, investigations of airline maintenance events also identify organisational-level factors such as: training and qualification systems, the allocation of resources, and the cultural or value systems that permeate the organisation. For example, a maintenance violation—such as using an incorrect tool—may occur because the correct tool was not available, which in turn may reflect equipment acquisition policies or financial constraints. One of the most common reasons given for maintenance violations is time pressure, and this in turn may be symptomatic of organisational conditions such as planning, staffing levels or work scheduling.

An acknowledgement of the organisational influences on maintenance error is sometimes misconstrued as an attempt to absolve maintenance technicians of responsibility for their work, or to shift blame from workers to management. Yet just as positive outcomes such as profitability, on-time performance, and customer satisfaction are indicative of the performance of the entire organisation, so too, negative events such as maintenance lapses are often a product of organizational processes.

Although human factors problems in maintenance are usually revealed through the actions of technicians, the solutions to these problems usually require system-level solutions, as described in the next section.

“While all involved in aviation safety must
be prepared to take responsibility for their
actions, a punitive response to genuine
errors is ultimately counterproductive.”

Managing the risk of maintenance error—Error management systems
Within airline maintenance, there is an increasing emphasis on error management as an integral part of an organisation’s safety management system (SMS). An SMS is a coordinated approach to the management of safety that goes beyond regulatory compliance. According to the International Civil Aviation Organization (ICAO), an effective SMS requires strong management commitment and attention to concerns ranging from corporate culture to event investigation and human factors training.1

A significant problem facing maintenance organisations is how to encourage the disclosure of maintenance incidents that would otherwise remain unknown to management. Despite the extensive documentation that accompanies maintenance, the day-to-day work of maintainers may be less visible to management than the work of pilots or controllers. Pilots work under the constant scrutiny of quick access recorders, cockpit voice recorders and flight data recorders, not to mention passengers and the public. The performance of air traffic controllers is carefully monitored, and their errors tend to become immediately apparent to either fellow controllers or pilots. In contrast, if a maintenance engineer has a difficulty with a maintenance procedure at 3 a.m. in a remote hangar, the problem may remain unknown to the organisation unless the engineer chooses to disclose the issue. Once a maintenance error has been made, years may elapse before it becomes apparent, by which time it may be difficult to establish how it occurred.

Incident reports are one of the few channels for organisations to identify organisational problems in maintenance, yet the culture of maintenance around the world has tended to discourage the open reporting of maintenance incidents. This is because the response to errors has frequently been punitive. In some companies, common errors such as leaving oil filler caps unsecured will result in several days without pay or even instant dismissal. It is hardly surprising that many minor maintenance incidents are never officially reported. When Australian maintenance engineers were surveyed in 1998, over 60 percent reported having corrected an error made by another engineer without documenting their action, to avoid potential disciplinary action against the colleague.2

While all involved in aviation safety must be prepared to take responsibility for their actions, a punitive response to genuine errors is ultimately counterproductive. Some in the aviation industry have proposed that a “blame free” culture is necessary to encourage reporting. This could imply that no-one would ever be held responsible for their actions. More recently, the concept of “just culture” has been promoted, in which some extreme violations will result in discipline; however, most will not.

“To arrive at the organisational root causes of
a mishap involving human performance,
we need to ask ‘Why?’ repeatedly:
Why did the behaviour occur?”

Incident reporting programs in maintenance
Progress is slowly being made towards error reporting systems that enable maintenance engineers to disclose genuine mistakes without fear of punishment. Part 145 of the European Aviation Safety Agency (EASA) regulations requires maintenance organisations to have an internal occurrence reporting scheme that enables occurrences, including those related to human error, to be reported and analysed. In 2001, prior to the release of the EASA requirements, the UK Civil Aviation Authority released Airworthiness Notice 71, outlining best practices on maintenance error management. These included corporate commitment, a clear discipline policy, and an event investigation process. Transport Canada has also promulgated regulations requiring safety management systems for airlines. This requirement includes the reporting of errors and other problems, and the internal investigation and analysis of such events.

In the United States, the Federal Aviation Administration (FAA) encourages airlines and repair stations to introduce Aviation Safety Action Programs (ASAP) that allow employees to report safety issues with an emphasis on corrective action rather than discipline. Incident reports are passed to an event review committee comprising representatives of the FAA, management and the union.3 Despite the advantages that these programs offer, they have been adopted more widely for flight crews than for maintenance personnel. Not all incidents are accepted into ASAP programs. Some of the key conditions for accepting a report are as follows:

  1. The report must be submitted in a timely manner, generally within 24 hours of the reporter becoming aware of the problem.
  2. The incident must not involve criminal activity or substance abuse.
  3. The incident must not involve intentional falsification.
  4. The incident must not involve intentional violations or actions that reflect “intentional disregard for safety”.

The first three of these criteria are unlikely to pose a problem in most cases. However, when it comes to violations or actions that involve an “intentional disregard for safety”, the matter becomes more subjective. Many routine violations in maintenance could fit this criterion.

The issues of blame and justice apply to more than just maintenance personnel on the hangar floor. Managers and supervisors are also responsible for the performance of the personnel who report to them. It has been proposed that when workplace violations occur, there should be consequences not only for the individuals directly involved but also for managers. For example, if an incident involved a routine rule violation, managers should be called to account for their failure to ensure compliance or their failure to change the rule if it was an unnecessary one.4

Human factors training
From the 1970s onwards, airlines around the world began to provide human factors awareness training for flight crews. Until relatively recently, human factors training was rarely provided to maintenance personnel.

In the 1990s, an initial wave of maintenance human factors training courses began in the U.S., modelled on successful cockpit resource management training. This early training was typically referred to as maintenance resource management (MRM) and focused on topics such as: assertiveness, stress management, decision making, awareness of norms, communication skills, and conflict resolution. Courses typically aimed not only to change attitudes among maintenance personnel but also to provide them with practical skills that could be applied in the workplace, such as assertiveness skills and conflict resolution techniques.

A second wave of maintenance human factors training has been generated by new requirements from ICAO, EASA, and Transport Canada that call for maintenance staff to have knowledge of human factors principles. EASA Regulation 66 lists human factors knowledge among the basic initial knowledge requirements for certifying maintenance staff on commercial air transport aircraft. The recommended syllabus includes teamwork, working with time pressure and deadlines, communication, and the management of human error. Although these syllabus items are listed in the appendix to the regulation as an “acceptable means of compliance,” EASA has not listed alternative means of compliance, so this syllabus effectively has the force of a regulatory requirement.

The related EASA-145 contains extensive human factors requirements for maintenance organisations. Among the requirements in these regulations and the associated support documents, are that personnel receive training in human factors principles. This training is required not only for certifying staff, engineers and technicians but also for managers, supervisors, quality control staff, store personnel and others. Human factors continuation training must occur every two years. Over 60 human factors topics are listed in the guidance material associated with EASA-145, including violations, peer pressure, memory limitations, workload management, teamwork, assertiveness, and disciplinary policies. The Civil Aviation Safety Authority has indicated that similar regulations will apply to maintenance organisations and personnel in Australia in the future when Civil Aviation Safety Regulation (CASR) Part 145 is introduced.5

Learning from incidents
In most cases, the immediate circumstances of a mishap are symptoms of deeper, fundamental problems. Treating the symptoms of a problem will rarely lead to adequate solutions and may even make things worse. For example, enforcing compliance with a routinely ignored procedure may cause more harm than good if the procedure is unnecessary or poorly conceived. To make lasting improvements, we need to identify and treat the underlying fundamental origins, or root causes, of mishaps.

To arrive at the organisational root causes of a mishap involving human performance, we need to ask “Why?” repeatedly: Why did the behaviour occur? Why did risk controls fail? Why did the contributing factors exist? Repeatedly asking “Why?” eventually leads us to fundamental aspects of the organisation that can have powerful and wide-ranging influences on safety and quality.

Incident investigation systems
Incident reports provide valuable raw material from which safety lessons can be extracted. In recent years, several investigation techniques have been developed specifically for airline maintenance.

The oldest of these, Boeing’s Maintenance Error Decision Aid (MEDA) presents a comprehensive list of error descriptions, such as “access panel not closed”, and then guides the investigator in identifying the contributing factors that led to the error. Over 70 contributing factors are listed, including fatigue, inadequate knowledge, and time constraints.6 The system, however, does not include psychological descriptions of errors.

The Aircraft Dispatch and Maintenance Safety System (ADAMS) was developed in Europe by a team based at the Psychology Department of Trinity College Dublin. In common with MEDA, ADAMS includes a range of maintenance errors but also enables the investigator to describe the psychological form of the error using a large range of descriptions such as habit capture and memory failure. The investigator is provided with a choice of approximately 100 performance influencing factors covering the task, the work environment, the organisation, and the error-maker’s physical and mental state7.

The Human Factors Analysis and Classification System (HFACS) is based on the Reason model and was originally developed to assist in the investigation of mishaps in the U.S. military. A maintenance extension of this methodology (HFACS-ME) was developed by the U.S. Navy to analyse aviation incidents.8 HFACS-ME assists the investigator in identifying maintenance actions using a taxonomy based on that of Reason, and provides 25 potential latent conditions that contribute to maintainer errors. Perhaps due to their military origins, HFACS and HFACS-ME emphasise supervisory factors.

There are two key advantages of using a structured and systematic error investigation system such as those described above. First, structured investigation systems have been shown to improve the effectiveness of investigations. Structured systems serve as prompts or checklists that assist the investigator with uncovering relevant issues during the investigation process. Second, once the system has been in use over time, a bank of incident data becomes available in a standard form that is suitable for statistical analysis. It then becomes possible to search for trends and associations in the data that may not otherwise have been identifiable.

This work is copyright. In the interests of enhancing the value of the information contained in this publication, you may copy, download, display, print, reproduce and distribute this material in unaltered form (retaining this notice).
©Commonwealth of Australia 2008.

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1 International Civil Aviation Organization (2008). Safety Management Manual (SMM). 2nd ed. (Doc 9859).

2 National Transportation Safety Board (1992). Continental Express, Embraer 120. Aircraft Accident Report 92/04.

3 Federal Aviation Administration, Advisory Circular (AC) 120-66B.

4 Hudson, P. (2000). Safety culture and human error in the aviation industry: In search of perfection. In B. Hayward &A. Lowe (Eds). Aviation Resource Management. Ashgate: Aldershot.

5 Civil Aviation Safety Authority (2006), Notice of Proposed Rule Making. A Proposal to Modernise and Harmonise Rules for the Maintenance of Australian Aircraft and Licensing of Aircraft Maintenance Personnel (Document NPRM 0604MS), Canberra: Author.

6 Rankin, B. &Allen. J, (1996). Boeing introduces MEDA, Maintenance Error Decision Aid. Airliner, April–June, 20-27.

7 Russell, S., Bacchi, M., Perassi, A., &Cromie, S. (1998). Aircraft Dispatch And Maintenance Safety (ADAMS) reporting form and end-user manual. (European Community, Brite-EURAM III report. BRPR-CT95-0038, BE95-1732.) Dublin, Ireland: Trinity College.

8 Schmidt, J. K., Schmorrow, D. &Hardee, M. (1998). A preliminary human factors analysis of naval aviation maintenance related mishaps. SAE Technical Paper 983111. Warrendale, PA: Society of Automotive Engineers.

Repair and Overhaul Challenges

by Brad Taylor, Civil Aviation Safety Inspector, Maintenance and Manufacturing, Standards, Civil Aviation, Transport Canada

The majority of aircraft owners and operators currently enjoy an established product support base that includes the original equipment manufacturer (OEM) as well as distributors and maintenance, repair or overhaul (MRO) facilities. When they require services or spares, aircraft owners and operators have many options to choose from and rarely need to concern themselves with the acceptability of the products or services they receive. Not everyone is so lucky!

During the design and conception phase of new aircraft development, the manufacturer attempts to determine the anticipated service life of new models, including variants thereof, in order to build an airframe capable of lasting that duration. In many cases, aircraft have found niche markets where they are utilized far longer than anticipated and in unpredictable ways. Operators with businesses founded on satisfying these market needs with unique aircraft—which sometimes operate far past any projections—are faced with a unique challenge in keeping their aircraft in the sky and their business afloat. In many cases, the established support industries are long gone or exist in parts of the world where the aircraft is still found in numbers sufficient to warrant their existence.

What would you do if the support network for your aircraft started to shrink as the aircraft model aged and was slowly removed from service? Perhaps, through word of mouth and the Internet, you might discover that the parts and/or services you need are available in another country. You do the research by reviewing Airworthiness Notice (AN) B073 and the Canadian Aviation Regulations (CARs) and by consulting your principal maintenance inspector (PMI) or local Transport Canada office. Through your research, you discover that Transport Canada Civil Aviation (TCCA) doesn’t have an agreement to allow for acceptance of parts manufactured or repaired in the country you identified. You’re stuck in a situation where it appears that you cannot maintain your aircraft due to regulatory barriers. Have you exhausted all your options within the boundaries of the regulatory system, or could you have done more? You have four real options that should allow you to achieve acceptable results:

  • Locate a Canadian approved maintenance organization (AMO) capable of performing the work required or willing to add the ability to their existing capabilities list.
  • Locate a foreign MRO facility that is acceptable within the scope of TCCA’s international agreements.
  • Consider modifying your aircraft with newer equipment through one-off approvals or supplemental type certificates (STC).
  • Contact TCCA to discuss other possibilities as a last resort.

When you have exhausted all domestic options and begin to look at foreign sources, you will find that TCCA doesn’t currently have any Foreign Approved Maintenance Organizations (FAMO) outside of the current international agreements. Therefore, a search in this genre should start and end within the current list of countries with which Canada has developed agreements. Companies within the scope of the agreements must also have CAR 573 approval, unless they are Federal Aviation Administration (FAA)-approved repair stations. The bilateral agreement between Canada and the United States is different from the agreements with the European Aviation Safety Agency (EASA) and other countries in this regard. In fact, each agreement is different, which means that you must familiarize yourself with the details of the relevant agreement before doing business in that country.

Another common misconception is that foreign OEMs are automatically granted the ability to maintain their product because it has been approved for use in Canada. The distinction between manufacturing and maintenance approvals becomes blurred by the fact that you are dealing directly with an OEM. The person signing the maintenance release assumes complete responsibility for the work performed and the parts used during maintenance under CAR 571.10. Therefore, it is their responsibility to ascertain whether the maintainer of the product is acceptable under the CARs. The origin, condition and supporting documentation that accompanied the product must be evaluated prior to deciding whether or not you will install it on an aircraft. This holds true even if you’re releasing an aircraft with your Aircraft Certification Authority (ACA) approval granted by an AMO. In this particular situation, you must be certain that the MRO side of the OEM has received Canadian approval to maintain the product and that they certify it in accordance with the terms of the applicable international agreement.

Many people believe that simply having a completed Authorized Release Certificate in hand makes the identified part acceptable for installation. In reality, the document must be reviewed closely to ensure that it is completed properly, is actually for the part in question, and has been issued by an acceptable facility. There are many FAA-approved repair stations capable of issuing 8130-3 repair certificates that TCCA does not recognize, simply because they are located outside of the United States. Aeronautical products maintained and certified by these facilities are not acceptable for installation on Canadian aircraft, despite the fact that they have what appears to be acceptable documentation. The reason for this is really quite simple and is explained thoroughly in AN B073, but it bears repeating here. Our bilateral agreement with the United States extends only to the parts of the industry over which the FAA exercises direct oversight. When the FAA enters into an agreement with another country and that country has agreed to perform oversight on behalf of the FAA, the FAA no longer exercises direct oversight with the repair stations located there. The same is true for EASA and any countries with which it has additional agreements.

In reality, the onus is on you to stay abreast of the changes and keep current in your understanding of how to conduct business. It would be convenient if there were a system to throw up red flags anytime changes that affect you and your organization occur, but that just isn’t the case. A keen eye on industry publications will generally assist you in this effort; monthly review of the CARs revisions and international agreements applicable to your operation should do the rest. Only you know where your liabilities lie, and only you can be held accountable in the end for compliance with regulations. You are expected to manage your risk and proactively deal with the challenges of repairing and overhauling your aeronautical products by staying informed.

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