REGARDS
SANDEEP KEELU

First, Licensed Aircraft Maintenance Engineers (LAME) fall under the demarcations set out by the local airworthiness authority and the rules within Part66 of CAA rules. Maintaining the maintainers? LAME's have a delegation authorized by the CAA to certify maintenance iaw the above rules within the boundary's of his/her ratings and category.
Those who do not reflect on history are distend to repeat it. Human Factors research has influenced the overall safety of aircraft operations and maintenance.

A better question to ask is, Without Human Factor Research and interventions within aviation, how would this effect overall aircraft safety? I assume in the essence of safety, the answer is reasonably clear.

REGARDS
SANDEEP KEELU

REGARDS

SANDEEP KEELU

Does anybody has knownledge about Rolls Royce's Direct Accumulation Counts (DACs) for LLP's Calculation for RB211-535E4?

I have just read your email. Probably at this time you have made your decission.

Your diploma in A/C maintenance Engineering should be also applicable to work in modifications to the certified design ( called Type Design or Supplemental Type Design STC _ you may check FAA and EASA sites for more information). Within this field, you may dedicate to aircraft interiors design. As an engineer you will be not only able to draw a nice artistic concept but ALSO consider the technical complexities of the certification (ie Cabin Safety) , installation, testing and maintenance. There is a huge working area in Aircraft Interiors wnere creativity and artistic care are very appreciated. You may take a look on the site www.aircraftinteriorsinternational.com.
Good luck and go ahead! Then I wish you Selamat Jalan……

Warm regards

Juan

maintaining the maintainers? What impact has human factors research and intervention had on overall aircraft safety?

Myself and other Aircraft Engineers will agree the above statement is rubbish!

First, Licensed Aircraft Maintenance Engineers (LAME) fall under the demarcations set out by the local airworthiness authority and the rules within Part66 of CAA rules. Maintaining the maintainers? LAME's have a delegation authorized by the CAA to certify maintenance iaw the above rules within the boundary's of his/her ratings and category.
Those who do not reflect on history are distend to repeat it. Human Factors research has influenced the overall safety of aircraft operations and maintenance.

A better question to ask is, Without Human Factor Research and interventions within aviation, how would this effect overall aircraft safety? I assume in the essence of safety, the answer is reasonably clear.

Background

Embedded as a customer within an overseas-based aviation contractor working on an aircraft avionics upgrade project, I observed and experienced multiple safety incidents related to standard operating procedures. Documented below are two examples which highlight the importance of following procedures, describe the consequences of not following procedures, and demonstrate poor communication within an aviation organisation. Arguably, these examples demonstrate defences preventing potential accidents.

INCIDENT 1: CAPTAIN YOUR TEST FLIGHT IS DELAYED.

During the flight testing program the aircraft was configured for a particular serial and dispatched by the contractor in preparation for flight. As a part of this standard procedure/process the contractor maintenance team was to brief the aircrew on the serviceability state of the aircraft (during the pre-flight brief). The brief included the following:

• Project installations which had occurred since previous flight,
• Maintenance and repair carried out on the aircraft since last flight,
• Long term acceptable defects to be carried on the flight,
• General servicing and replenishment information,
• And any other relevant information pertaining to maintenance on the aircraft.

On this occasion the brief was completed and it was announced that the aircraft was serviceable for flight. When aircrew pre-flight was complete the contractor produced its maintenance release form fully signed, the aircraft maintenance log book was signed and the aircraft was released for flight.

As the aircrew were strapping into their seat and the aircraft ladder was about to be lifted the contractor’s quality assurance lead wandered into my office and handed me some paperwork. The paperwork indicated that during the evening the nightshift maintenance team had carried out rectification on a long-term defect on the autopilot system. Further inspection of the paperwork suggested that after a re-wire of a connector in the autopilot system, no functional and independent functional had been carried out. These are standard maintenance procedures. The contractor who briefed the aircrew on maintenance made no reference to this autopilot work and in fact had no idea the work had been carried out over night by the other shift.

After a quick exchange of words with the contractor I immediately went out to the aircraft to explain to the captain that his flight was going to be delayed, and that he needed to sign the aircraft back to maintenance so the contractor could carry out the functionals prior to the aircraft flying. Of note, in 25 years of working in aviation maintenance it was the first time I had to prevent an aircraft from flying.

Potential Safety Implications

The safety implications of this maintenance error have the potential to be catastrophic. An example would be an incorrectly wired autopilot system has the potential to place the aircraft in an incorrect sense (attitude). A functional and independent function confirms the autopilot system operates in the correct sense.

Incident Cause

• Lack of adherence to standard operating procedures.
• Poor communication between the two functional elements in the contractor’s maintenance team.

Human Factors Lessons

It could be argued system defences captured this error prior to the aircraft taxiing but in reality it was a matter of timing which allowed this error to be picked up. Equally it could be argued if there was a problem on engaging the autopilot the pilot's skills, expertise and SOP's would mitigate the likelihood of an accident. However, if this maintenance error remained latent and lined up with other active and latent errors, and defences were breached, then a major accident could occur (Accident Causation Model).

Two important lessons can be derived from this incident:

• Standard operating procedures are an important element in a safety management system. Procedures are put in place to reduce error and mitigate consequences of error so they should be followed, and this ethos should be followed in all levels of the organisation.
• Communication is an important aspect of a safety management system. It allows information flow from top/down and bottom/up. The positive aspects of good communication contribute to safety and efficiency. In this case good communication between the maintenance shifts would have highlighted the functionals were not carried out and the customer would have been fully informed that the work had been completed.

INCIDENT 2: SAFETY LOCKING DEVICES AND PROCEDURES.

During standard post-flight maintenance on the aircraft described in incident one, the contractor’s maintenance staff were required to follow the customer’s standard operating/maintenance procedures, and these were laid out in the form of work cards.

On this aircraft there are two hydraulically activated large doors on the underside of the aircraft. To make these doors safe there is a safety pin (locking device) which is inserted at all times on the ground which prevents the inadvertent or accidental actuation of the doors with the aircraft hydraulic systems powered on the ground.

In short on two occasions this procedure was not followed correctly and the safety pin was inserted incorrectly, and on both these occasions the error was made by the same tradesman. On both occasions the error was noticed by customer representatives and brought to the attention of the contractor’s line management. Of note, no ground safety incidents were raised for these errors because an easily accessible, non-punitive and anonymous safety reporting system was not in place, and if there was it was not communicated well.

In the weeks following this incident another procedural issue occurred with contractor’s staff which involved the application of external power to the aircraft without using standard operating procedures. On this occasion, one of the aircraft hydraulic systems was left on when power was applied and there were people standing in area where the doors close. If this error had occurred with an incorrectly inserted safety pin and incorrectly positioned door switch (a part of external power on check), an accident would have been inevitable. This tradesman’s failure to follow procedures was investigated as a result of this incident and she was given remedial training.

Potential Safety Implications

The safety implications of this error have the potential to be fatal. In short, if a person was caught in these doors as they were being closed they would be literally cut in half.

Incident Cause

• Lack of adherence to standard operating procedures.
• Poor or lack of thorough training for the contractor maintenance team on aircraft type.
• The competence of the tradesman could be questioned.
• After discussing the incident with the tradesman he was hesitant about notifying his management of uncertainty or lack of confidence in carrying out the task correctly.
• Poor design on the aging aircraft which could allow the pin to be fitted incorrectly.

Human Factors Lessons

This incident highlights latent errors documented in the Accident Causation Model. Important lessons can be derived from this incident:
• Standard operating procedures need to be trained, followed and their use embedded in the organisations safety culture.
• Training to generate expertise is an important aspect to be managed in a safety management system.
• Building a safety culture with open communication is important in aviation organisations. A ‘rule with an iron fist’ type attitude has no place in aviation at all organisational levels. This would help to mitigate tradesman having fears of ‘putting their hand up’ when they are uncertain, uncomfortable or feel safety and efficiency is being compromised.
• The value in having an easily accessible, non-punitive and anonymous safety reporting system has a necessary place in aviation organisations to allow collection of data on near-misses, incidents and accidents. This will provide data for reducing error and mitigating error consequences.
• Redesign of the safety pin (locking mechanism) is a valid option.

Interestingly I work for the same organisation as others who have posted information on maintenance fatigue in this forum, and I would like to comment on an experience I endured while working on a project team.

The organisation I am employed with and its management are well known to employ insufficient manpower on project teams to save costs and this particular project was no different. The project involved the upgrading of the avionics systems on an aging, turboprop aircraft by an overseas based contractor. The project team to be discussed was the customer in this upgrade and our responsibilities involved:
• Maintaining quality assurance,
• Ensuring the project met the contract specification,
• Providing operational and engineering liaison with the contractor,
• Ensuring the basic aircraft systems (non upgraded systems) were serviceable,
• And to ensure my organisation’s standards and documentation were correct and complete.
My role was the lead flight line/hanger specialist on aircraft type in a small engineering and maintenance team with four members (2x engineers and 2x senior technicians).

Over three and half years the aircraft was subjected to a major upgrade to its systems followed by integration and test phase. While the aircraft was in the hangar it was regularly inspected and serviced while in preservation. Prior to the flying phase the aircraft was subjected to a comprehensive wake-up servicing plus functional testing.

As the customer, our under-manned engineering team was responsible to ensure we were ready to fly and all the documentation was complete by a certain date, and this dead line had been set under the contract. The final few weeks leading up to the first flight (Functional Check Flight) were hectic due to the significant amount aircraft documentation, recording and aircraft inspections required. In short, to achieve this task our team worked on average 14-18 hours per day and weekend work for over a week to achieve the deadline. The task was complicated by poor and slow documentation of the work completed by the contractor. In the end our small team met the deadline and the aircraft completed its post-upgrade flight with reasonable success, apart from a flight safety incident which was unrelated to any of the engineering teams actions.

This experience has left lasting impression for me personally of what not to do in aviation and as an aviation human factors manager. Our small team was physically and mentally fatigued after 4-5 days but we pushed on to achieve the task, with a ‘can do attitude’. Key fatigue issues experienced included:
• Making mistakes with the documentation (which were corrected),
• Lost concentration during inspections where I had to walk away at times to clear my thoughts,
• Behavioural issues (Short temper),
• General tiredness and malaise with degrading health and appearance,
• Observation similar issues with my fellow team members.

At one point in the process one of the engineering leads and I put our hands up to demand a break, which did occur but was still not sufficient to relieve our fatigue. We also requested more staff during this period but continually had replies suggesting there was no money to make this happen and no staff available to supplement the team. Operational staff observed and expressed their concern to management of the hours worked by engineering, but the reality was that meeting the deadline was more important, especially for the contractor. Eventually, during the flight testing program, our concerns were recognised and the team’s composition was increased. However, it could be argued the manpower increase was valid and still required at the later date but should been actioned prior to the start of flight testing.

From this experience I learnt the following lessons:
• Fatigue in aviation maintenance is a real threat. Fatigue has the potential to generate latent errors which may go unnoticed until errors line up to create an accident (See Accident Causation Model)
• As a human factors manager in aviation projects or any aviation maintenance operation it is important to ensure there is enough employees or time to allow careful management of employee health and fatigue. This approach will maintain safety and keep the operation more efficient.
• As a human factors manager in aviation maintenance there is a requirement to be aware and understand the risks of pushing team members to their extremes and in this circumstance there was no true requirement. Note, it must be understood in some organisations like the military, there may be a necessary requirement to work to extremes (although it is discouraged).
• As a member at all levels in aviation organisations, and in the interest of maintaining safety and efficiency, there should not be any hesitation in notifying management of unsafe circumstances and practices.
• There is no place for the ‘can do’ approach in aviation if it has negative consequences on safety and efficiency.
• I would like to endorse the lessons learnt on fatigue described by Charger007 and Robere in this forum.
• SAFETY is a key requirement or outcome in any aviation maintenance or project activity so contract deadlines and financial drivers must NOT take precedence.

This shift pattern had substantial potential for a team of four individuals to become extremely fatigued via substantial changes in their sleeping patterns and circadian rhythms.

I was part of an early team who had a shift pattern very similar to the one described. We had worked the previous week’s night shift, had dispatches to undertake to facilitate flying in the weekend and then the aircraft we were responsible for had parachute tasking during the week which required us to start most days at 4:30 am. This shift pattern, in hindsight, left us very fatigued and greatly increased the risk of errors to occur.

An error did occur during the early shifts, thankfully though it was not a substantial one and certainly no one was in any danger, but it was an error none the less. The aircraft we had to dispatch required that their fuel tanks have a fuel drain conducted every dispatch. On the Thursday morning of our shift the four of us all assumed that someone else in the team had conducted the fuel drains. This assumption was incorrect. Normally this sort of assumption would not have occurred, so to speculate was it the fatigue that led the four of us to an assumption. This error was picked up by the aircrew when they queried if the fuel drains had been completed. Each of us then realised that our assumption was incorrect. The fuel drains were subsequently completed and the aircraft was only delayed 20 minutes.

Lessons

Shift patterns and work-loads have a massive impact in maintenance technicians fatigue levels and need to be managed better than in this example.
There is absolutely no place in aviation for assumptions.

Wonder who you were working for.

An excellent lesson on maintenance fatigue. I work for the same organisation and became aware through a variety of experiences how fatigue was managed differently for aircrew and maintenance.

Aircrew have strict rest and duty requirements that are exceeded in only rare instances and with good justification. Yet maintenance crews work exceedingly long shifts in order to present serviceable aircraft for the scheduled flying. On deployments shifts can be over 12 hours long with short rests. On occasions I noticed the effects of this cumulative fatigue manifesting in behaviors and maintenance events. One event that was reported, involved a propeller almost being lifted incorrectly. Had an aware technician not stopped the lift the result surely would have been damage to the tune of thousands of dollars not to mention the indirect costs of lost flying time and experience.

I made a couple of deductions from that experience. Firstly fatigue on maintenance can have similar effects to safety and efficiency that it does on aircrew and therefore needs to be managed just as carefully. Secondly as a manager on the organisation I relied to much on my 'know how' style of management and needed to incorporate other styles such as a functional perspective and dare I say it a legislative approach in order to impose some limits to the hours the maintenance shifts were pulling.

How the crew dynamics worked whilst transiting internationally was that once the aircraft was on the ground and at its allotted parking spot for the night it was the maintainers job, usually one aircraft trade & one avionics trade, to conduct the after-flight servicing as quick as possible, as the air crew waited for the maintainers before travelling to the hotel as a group. This situation put an amount of pressure on the maintenance team to be as swift as possible with their maintenance. At the time I was not overly aware of Human Factors and its various disciplines, but now with the benefit of hindsight and some extra training I can fully see that this situation could have lead to errors occurring during the after-flight maintenance. The solution is a simple one, looking back, have two separate transports to the crews allotted hotel.

During one of the after-flight maintenance checks a fault was discovered. Luckily we had the spares for the fault on board the aircraft but the testing post the component replacement was lengthy. The aircrew left for the crew accommodation without the maintenance team to prepare for the next days flying and get the required amount of rest. The component replacement and subsequent testing went well but took the maintenance team approximately 6-7 hours. We then also travelled to the hotel to get some rest. The next morning (very early) when the entire crew left the hotel to ready the aircraft for the days flying we had only had limited sleep and travelling through time zones didn't make things any better. To confound the issue even more we were heading home after two weeks away where the flying schedule was constant. So for us as maintainers we had three individual factors that fatigued us that morning; we had limited sleep the night before due to working late on the aircraft, we were travelling through time zones and we were nearing the end of two weeks flying. Subsequently on that pre-flight I failed to secure the panel correctly which covered the Integrated Drive Generator (IDG) poppet inspection area. This error was also missed by my aircraft maintainer and the co-pilot on their walk around.

On engine start and push back the panel popped open and the engine start was aborted via the airport ground crew alerting the air-crew to the issue. The ground crew at the airport subsequently closed the panel and the flight continued as per the schedule.

Again looking back at this incident I can recognise the Human Factor considerations that were not considered. The aircrew, as they rightly should, strictly adhere to their crew duty periods. However the maintenance team did not have a rigid duty period as the aircrew. This usually was not a major issue but in this case there where three separate factors that came together and created a level of fatigue where I failed to conduct my duties as a I would have if I had not been fatigued. Luckily in this instance the panel was spotted and remedied before any catastrophic incident could have occurred.

Lessons

• Don't be pressured into hurrying work when there is no real urgency present.
• Be aware of your and your fellow workers limitations in terms of fatigue. Be especially vigilant when ending a long period of duty or other when other factors create excessive fatigue

Background

The engine in question was a rental engine which was being used by an operator while the operator’s engine was being overhauled at an engine shop.

Once the operator’s engine was completed the rental engine was removed by an engineer and the rental engine was then to be sent to another operator ASAP. The engineer was placed under pressure to ensure that a 2 day engine removal and install job was done in 8 hours. The pressure came from management who required the rental engine to be sent to another aircraft that without the rental engine would cause the aircraft be AOG (Aircraft on the Ground). If the aircraft went AOG the contract the aircraft was carrying out could have been cancelled. Therefore the engineer was being placed under a large amount of pressure which was totally commercially based.

The engineer removed the rental engine and placed it into the transportation box without carrying out the companies standard practices that dictate what should be done to an engine after it is removed from an aircraft. These checks included but are not limited to a check of the engine intake for the condition of the compressor and a look over the engine for any obvious signs of damage. The standard procedures also dictated that the engine should have a removed serviceable tag placed on the engine after these checks had been carried out, and an entry needed to be made into the engine log book. This is done so that the serviceability status of the engine was known in line with standard CAA regulations.

The engine arrived after a few days at the next operator’s aircraft supposedly ready for installation. The engineer fitting the rental engine noticed that the log book had not been filled in and the engine did not come with the standard serviceable tag attached. He then decide to carry out the checks that are required before fitting an engine and found the compressor had damage beyond the manual limits which made the engine unserviceable and caused the aircraft to be grounded.

Findings:

The engineer who removed the engine did not follow company procedures and CAA regulations.

The engineer who removed the engine was placed under pressure to carry out a job that was meant to take 2 days but the engineer was only given 8 hours thus leading to crucial steps in the process being missed or skipped.

Human factors were a major cause in the errors that occurred because of the pressure placed on the engineer to carry out the task in an unachievable time period. Thus short cuts were taken to meet those targets

Conclusion:

Management placed undue commercial pressure on the engineer to perform a task in an unachievable time period. The engineer had to take short cuts to ensure that the time targets set for him where achieved thus causing a chain of events to occur that led to the eventual grounding of an aircraft.

Human factors played a large role in this instance due to the fact that pressure placed upon an individual caused the individual to take steps that they would normally not even consider. The pressure was caused by management who may have thought at the time they were looking after the companies interests by getting an engine to the operator as soon as possible but in the end that decision led to a chain of events that eventually ended up costing the company anyway.

The root cause of this incident has to be placed on the management of the engineers company as they placed undue pressure on an individual who in the end made errors that led to the grounding of an aircraft.

Staff who feel that a manager looks after their needs in terms of ensuring they have all the necessary equipment,training and adequate pay to carry out the tasks that are asked of them, will in my experience have a positive attitude towards the work they are carrying out. This in turn leads to a reduced rate of human error within the maintenance organization as well as ensuring that a no blame culture exists between staff and management.

A maintenance organization that has a no blame culture ensures that when staff make a mistake they feel that they can inform management of the mistake and the failures within the systems and procedures will be looked at not the individual themselves. By ensuring that the systems and procedures are assessed when a mistake is made by a staff member, organizations show their employees that a no blame culture exists and that management are committed to a safe working environment.

Aviation maintenance managers have a rather difficult task of ensuring that maintenance is carried out within a budget and on time which ensures that aircraft operations are not affected. The only way that maintenance can be carried out properly on time and on budget is by ensuring that the safety systems in place are adequate and that staff are well trained and aware of their own human limitations. I have found that often engineers will work past their limits in terms of the length of time they will work in one shift. This will increase the risk of human error occurring and it is of utmost importance that a manager keeps track of the times his people are working and monitors the work they have carried out.

A good manager will have a positive influence on his staff and will ensure that safety and the reduction of human error is his main focus.

Background to the Incident

The turboprop engine was being run on a test rig after a hot section inspection had taken place in the engine shop. All parameters where normal for the first 1 hour of operation on the test rig when for no apparent reason there was a sudden increase in the EGT (Exhaust Gas Temperature). The two engineers carrying out the test run carried out an emergency shutdown of the engine immediately. Once the engine had stopped turning the engineers were then unable to turn the rotor by hand and the entire rotating group had locked up.

Investigation

The engine was stripped down and subsequently found that the internal oil feed tube which supplies oil to the rear internal bearing had fractured causing the oil to flow past the bearing and leading to a subsequent rear bearing failure caused by a lack of oil. The bearing failure caused the entire rotating group of the engine to move forward connecting with the stators inside the engine and subsequently destroying a large quantity of internal parts.

The investigation found that the rear bearing oil feed tube had not been installed correctly during final assembly of the engine. The tube had been installed on an angle and the stress placed on the tube had caused the pipe to fracture at the weld. The engineer who installed the tube was a very experienced engineer but he was new to the role and was still learning how to build this particular type of turboprop engine. The engineer insisted that he followed the procedure laid out in the maintenance manual which describe how to install and tighten the oil feed tube during assembly.

After checking the engine build sheets used to build this particular engine and the latest revision of the maintenance manual it appeared that all the build steps had been followed. It was only after speaking with an experienced engineer who had built many of these engines that the crucial step which had been missed was identified.

The experienced engineer explained that there were two manuals that they work out of depending on the maintenance that was required on the engines. For a hot section inspection the maintenance manual was used and for overhaul of this type of engine the overhaul manual was used. He explained that the overhaul manual calls for the use of an alignment tool when installing the rear oil feed tube but the maintenance manual does not. He explained that he used the alignment tool no matter what level of maintenance was called for on the engine as that area of the engine was always disassembled no matter what level of maintenance was being carried out.

Conclusion

1.The engine failed due to a lack of oil supply to the rear bearing because the rear bearing oil feed tube had failed.

2.The engineer used the correct manual for the assembly of the engine and followed the correct build procedures.

3.The maintenance manual failed to call up the use of the alignment tool for the installation of the rear bearing tube even though the overhaul manual calls up the use of the tool when carrying out the same task.

4.The experienced engineer in the shop accepted that the maintenance manual was incorrect and relied on his years of experience to ensure that the correct tool was used for the task.

This event is a very good example of human error playing a role in the failure of an engine during heavy maintenance. The maintenance manual for this particular engine type was written in the late 70’s and the task of using an alignment tool had never been written into the manual at the time it first came out. During the investigation it was found that the OEM (Original Engine Manufacturer) had never been told it was missing therefore I would suggest that engineers just accepted as a norm that the tool was not in the manual but used it anyway as part of their experienced gained over the years.

This is a very good example of a latent error as the maintenance manual was written almost 30 years ago and when an inexperienced engineer was following the manual step by step he inadvertently installed the tube without the alignment tool causing the tube to crack and the engine to fail on test. It took almost 30 years for this error to occur due to a step missing from the OEM maintenance manual but eventually the missing information in the manual was the catalyst for a failure to occur.

There are checks and regular scheduled maintenance that must be done on an aircarft, at the same time, due to normal wear and tear, there are also unscheduled ones. For example, when find a small crack on the wing spar during a routine inspection, the operator will be required to fix it. However, when times like in the case of the engine drinks a lot of oil, and sometime after a flight, there are oil on the gear door, and no apparent leaks or cracks are found, and from personal expereince, the aircraft was signed off and kept on flying, and continue to use large mount of oil, compare to the rest of the fleet.

Or in the case of the rule requires only one altimeter, according to Min Equip List (MEL), but the aircraft is fitted with two. When one reads significantly higher than the other, which one would you trust? From personal experience, I reported this to the engineer, and under IFR, I would want to have an accurate altitude indication. However, the response I got was average the altitude out. Imagine flying in a dark stormy night, with one altimeter in front of you, the other 1 meter away on the other side of the instrument panel, unlighted, at the same time of doing a NDB approach where tracking is already difficult enough, you have to work out the average indication between the two important instruments.

In organistions with strong financial back grounds, fixing those little problems is no big deal, such as big flying schools, or mainline airliines. But in the competitive commercail environment, for small aeroclubs, small cargo companies, fixing the "unneccessaries" are just not that practiccal, and it is a big risk for pilots out there.

The helicopter had been in the hanger for a scheduled 2000 hour airframe and engine check and the incident occurred during the post maintenance test flight.

The pilot took off and immediately after take-off had no tail rotor pedal control. He reported that the tail rotor pedals were jammed and he had no way of moving them or controlling the helicopter. The helicopter did a 180 degree spin and the pilot managed to land the helicopter safely on the grass facing the opposite direction it had taken off in. No injuries to personal or damage to the helicopter occurred during this incident.

The subsequent investigation found that a standard bolt had been used as a rigging pin (instead of the specified tool in the maintenance manual). A new tail rotor servo had been installed during the 2000 hour check and the bolt had not been removed post maintenance and had locked the tail rotor system when it was powered hydraulically during the flight test.
The subsequent investigation found that Human Factors had a major role to play in this incident and the following factors were identified:

1. Lack of resources to carry out the task:

A bolt was used as a rigging pin because management had decided that the stipulated rigging pin in the manual was to expense to purchase. This in turn led to the use of a standard bolt which was missed as it was not identified as a rigging pin and looked as if it was a part of the assembly.

2. Norms:

The lack of tooling in the company’s hanger was an accepted problem by the engineering staff. Maintenance personal was used to working with the incorrect tooling or no tooling at all and therefore did not see anything wrong with using a bolt as a rigging pin. It had become a norm and was accepted that management did not spend money on tooling

3. Lack of communication:

The pilot who carried out the post maintenance test flight and the maintenance personal had no formal way of communicating what post maintenance tests needed to be carried on the ground before the helicopter was flown for the first time. Both the pilot and chief engineer assumed that each person knew what was expected of them and this was not the case.

4. Complacency and assumptions:

During the investigation and after speaking with the maintenance personal and pilot it was found that the chief engineer assumed that the full rigging check had been carried. This was not the case and therefore the full rigging check was signed off on the maintenance tasks but nobody had actually carried out a full rigging check. The junior engineer assumed that a partial rigging check was called for as only a servo unit had been changed and therefore he thought that the rest of the control system was not disturbed. The MM calls for a full rigging check after a new tail rotor servo is installed.
The pilot did not carry out a full travel check of the rotor pedals during his pre-flight as he assumed that it would be ok. Therefore he did not follow the company standard operating procedures to carry out a full pre-flight especially for the first flight after heavy maintenance.

5. Pressure, fatigue and stress:

The chief engineer had to carry out to many functions during the maintenance check including managing the whole check, supervising the tradesmen, assisting with planning issues, assisting with material shortages and answering phone calls from other customers. This placed a large amount of pressure on him to complete the check on time as well as deal with running the day to day business in the hanger.
The chief engineer had a large amount of stress placed on him by the customer as the helicopter was already 3 days late and needed to be out making money for the customer.

Due to the hours the chief engineer and his staff were working to complete the check fatigue played a role in this incident and the staff where working way past the duty hours laid out in the NZCAA duty hour regulations for engineers.

Conclusion

The final conclusion of the investigation found that a whole range of human factors played a role in the bolt being used as rigging pin as described above. The root cause of the incident was a decision by management not to spend money on the correct tooling which in the end led to a situation where engineers had to use other means to get the check completed. Staff accepted that tooling and a lack of general resources was a part of working for the company and therefore nothing was done about the problems as engineers were tired of being told no by management when they asked for necessary things to be purchased.
Safety was not the first concern of management and commercial pressure as well as financial restraints led to an incident that could potential have been a lot worse.

In New Zealand the maximum duty time for persons involved in the maintenance of aircraft was changed by the NZCAA on the 1st March 2007. Two new rules where introduced; CAR 43.53 (11) and CAR 145.52.
Excerpt from CAR 43.53 below:

(11) not perform the maintenance unless he or she has been relieved
from the performance of maintenance on an aircraft or
component for—
(i) a period of at least 8 consecutive hours in the 24-hour
period immediately before the maintenance is performed;
and
(ii) at least 4 periods of at least 24 consecutive hours each in
the 30-day period immediately before the maintenance is
performed.

The two most significant changes introduced by these rules are:

1. The rules apply to ALL persons involved in the maintenance of the aircraft, not just the certifying persons as previous.
2. The time frames are based on rest proceeding the duty time as opposed to the requirement to rest after duty.

Although I believe that these rule changes are a step in the right direction they still allow for the development of significant fatigue. For example a person that has had four days off duty (96 hours) at the start of the month, would still be compliant after 20 plus days of 16 hour shifts with only 8 hours between. I for one, would not want to have such an individual performing maintenance on an aircraft.

Over the last 10 years there has been a marked improvement in the understanding of the effects of fatigue on the performance of maintenance personnel. It has been a few years since I have been asked to work more than 16 hour straight (my own personal record is around 26 hours).

The unfortunate thing about the above rule changes is that most organizations will incorporate them as is, into their procedures. Instead of a more active fatigue management process, which could account for other variables such as; heat, cold, noise, time of day etc.

I am interested in other people opinions on fatigue management in the aviation industry, be it in the maintenance sector or any other.