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100+ Free Part-66 Module 9 Practice Questions

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2026 Statistics

Key Facts: Part-66 Module 9 Exam

28 questions

Module 9 MCQ count (all categories)

Regulation (EU) 2023/989

35 minutes

Time allowed

Regulation (EU) 2023/989

75%

Pass mark per module

EASA Part-66

12 June 2024

2023/989 applicability date

Commission Implementing Regulation (EU) 2023/989

12 factors

The 'Dirty Dozen' precursors

Gordon Dupont, 1993

7 plus or minus 2

Short-term memory capacity

Module 9 Human Factors

12 June 2026

Deadline to finish under the old standard

Regulation (EU) 2023/989 transition

EASA Part-66 Module 9 Human Factors is a basic-knowledge module for the Aircraft Maintenance Licence (categories A, B1, B2, B3). It is examined by 28 three-option multiple-choice questions in 35 minutes with a 75% pass mark under Regulation (EU) 2023/989 (applicable 12 June 2024); the former essay was removed in June 2024 and the question count rose from 20 to 28. Content spans the need for human factors (Murphy's Law, maintenance accident statistics), human performance and limitations (vision, hearing, memory, perception, claustrophobia), social psychology (responsibility, motivation, peer pressure, culture, teamwork, leadership), factors affecting performance (stress, fitness, time pressure, workload, sleep, fatigue, shiftwork, alcohol and drugs), the physical environment and tasks (noise, fumes, lighting, vibration, working at height, inspection), communication and shift handover, and human error - error models (Reason's Swiss Cheese, SHELL), error types (slips, lapses, mistakes, violations), error management (MEDA) and the Dirty Dozen. This free bank uses 4-option questions for tougher practice.

Sample Part-66 Module 9 Practice Questions

Try these sample questions to test your Part-66 Module 9 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In EASA Part-66 Module 9, 'Murphy's Law' is frequently cited to explain why maintenance error controls are necessary. What does Murphy's Law state?
A.Errors are always caused by the least experienced person on the team
B.If something can be assembled or connected the wrong way, eventually someone will do so
C.The probability of an error doubles with every additional task in a shift
D.Human error can be completely eliminated through adequate training
Explanation: Murphy's Law in maintenance human factors is the principle that if a component can be fitted, connected or assembled incorrectly, sooner or later someone will do so. It justifies error-tolerant design and independent inspection.
2Why does Module 9 place such emphasis on human factors in aircraft maintenance rather than only in flight operations?
A.Maintenance tasks are always carried out in flight and so directly affect handling
B.A significant proportion of aircraft accidents and incidents have been linked to maintenance error
C.Maintenance staff are the only personnel not covered by flight crew training
D.Human factors only apply to engineering work and not to pilots
Explanation: Studies of accident causation show that maintenance human error is a recognised and significant contributor to aircraft accidents and incidents, which is why dedicated human-factors training is mandated for maintenance staff.
3A latent failure (or latent condition) in the context of maintenance human error is best described as:
A.An error that is detected and corrected before the aircraft is released to service
B.A failure of an electronic component caused by software corruption
C.An error that occurs only during the first flight after maintenance
D.An error whose adverse consequences may remain dormant and only become apparent later
Explanation: A latent error is one whose effect lies dormant within the system and only becomes evident when combined with other factors or triggering conditions, sometimes long after the maintenance was performed.
4The 1990 British Airways BAC 1-11 windscreen blow-out, often used as a maintenance human-factors case study, was caused primarily by:
A.Fitting of incorrect (undersized) bolts during the windscreen replacement
B.A design fault in the windscreen retaining frame
C.Failure to carry out a pressurisation test after the work
D.Corrosion of the airframe around the windscreen aperture
Explanation: The windscreen detached because the bolts used to secure it were too small in diameter; the engineer selected incorrect fasteners during a night-shift replacement, illustrating error-producing conditions and lack of independent checking.
5Within the eye, the cells primarily responsible for vision in low-light (scotopic) conditions are:
A.Cones, concentrated in the fovea
B.Ganglion cells in the optic disc
C.Rods, located mainly in the peripheral retina
D.The cells of the ciliary muscle
Explanation: Rods are highly sensitive to low light and are concentrated in the peripheral retina, providing night and peripheral vision, though they do not detect colour. Cones handle colour and detail in bright light.
6An aircraft technician who cannot distinguish certain wire colours may be affected by colour vision deficiency. In the human eye, colour perception is a function of the:
A.Rods
B.Iris
C.Cones
D.Vitreous humour
Explanation: Cones, concentrated at the fovea, are responsible for colour vision and detailed sharp vision in good lighting. There are three cone types sensitive to different wavelengths; a deficiency in one produces colour-blindness.
7Presbyopia, which commonly affects maintenance engineers from around their mid-forties, is the:
A.Loss of the eye's ability to focus on near objects due to reduced lens flexibility
B.Progressive clouding of the lens reducing overall clarity
C.Inability to distinguish red from green
D.Increased pressure within the eye damaging the optic nerve
Explanation: Presbyopia is the age-related loss of accommodation as the crystalline lens becomes less elastic, making it harder to focus on close work such as reading wiring diagrams or small part numbers, often requiring reading glasses.
8Prolonged exposure to high noise levels in a maintenance environment can cause noise-induced hearing loss. This type of hearing damage typically first affects the ability to hear:
A.Very low-frequency sounds
B.Only sounds above 15 kHz that are unimportant for speech
C.Higher-frequency sounds, around 4 kHz
D.Sounds in only one ear at a time
Explanation: Noise-induced hearing loss characteristically begins as a notch in sensitivity around 4 kHz, affecting higher frequencies first; this can impair the perception of consonant sounds important for understanding speech.
9In models of human information processing, the very brief store that holds incoming sensory data for a fraction of a second before it is attended to is called:
A.Sensory memory (sensory store)
B.Long-term memory
C.Working memory
D.Episodic memory
Explanation: Sensory memory briefly retains raw sensory input (visual or auditory) for a fraction of a second; only information that is attended to passes into short-term/working memory for processing.
10Short-term (working) memory is generally limited in capacity. According to the widely quoted figure used in human-factors training, it can hold approximately:
A.2 to 3 items for several hours
B.Unlimited items provided they are rehearsed
C.100 items for up to 5 minutes
D.7 plus or minus 2 items for around 15 to 30 seconds
Explanation: The classic figure for short-term memory capacity is about seven (plus or minus two) chunks of information, retained for roughly 15-30 seconds unless rehearsed; this is why long part numbers should be written down rather than memorised.

About the Part-66 Module 9 Exam

EASA Part-66 Module 09 (Human Factors) is one of the basic knowledge modules required for the EASA Aircraft Maintenance Licence in categories A, B1, B2 and B3. It teaches how human capabilities and limitations contribute to maintenance error and how to manage them, drawing on Reason's Swiss Cheese model, the SHELL model and the 'Dirty Dozen'. Under Commission Implementing Regulation (EU) 2023/989, applicable from 12 June 2024, the module is examined by 28 multiple-choice questions in 35 minutes with a 75% pass mark, and the former essay was removed. Pre-2024 courses must complete under the old standard by 12 June 2026.

Questions

28 scored questions

Time Limit

35 minutes

Passing Score

75%

Exam Fee

Approx. EUR 50-230 per module sitting (varies by NAA/Part-147 organisation) (EASA framework; examinations conducted by National Aviation Authorities or approved Part-147 maintenance training organisations)

Part-66 Module 9 Exam Content Outline

22%

Need for Human Factors & Human Error

Murphy's Law and the rationale for human-factors training, maintenance accident statistics and case studies, Reason's Swiss Cheese model (active failures vs latent conditions), the SHELL model and its interfaces, error types (slips, lapses, mistakes, violations), and error management with MEDA and independent inspection

20%

The Dirty Dozen & Hazards

The twelve common precursors - lack of communication, complacency, lack of knowledge, distraction, lack of teamwork, fatigue, lack of resources, pressure, lack of assertiveness, stress, lack of awareness and norms - their recognised safety nets, the hazard/risk distinction, and the hierarchy of controls

18%

Human Performance & Limitations

Vision including rods, cones, colour perception and presbyopia; hearing and noise-induced hearing loss around 4 kHz; information processing; attention, selective attention and inattentional blindness; perception and perceptual set; sensory, short-term (7 plus or minus 2) and long-term memory; and claustrophobia and physical access

16%

Factors Affecting Performance

Fitness and sub-clinical health; acute and chronic stress and the inverted-U arousal curve; time pressure and deadlines; workload overload and underload; sleep stages including deep NREM; the approximately 24-hour circadian rhythm and its early-morning low; fatigue and shiftwork; and the effects of alcohol, medication and drugs

14%

Physical Environment & Tasks

Noise; fumes, oxygen deficiency and confined-space/permit-to-work controls; illumination; climate; vibration and hand-arm vibration syndrome; working at height; physical and repetitive work; visual inspection and vigilance decrement; and complex systems and automation

10%

Social Psychology & Communication

Responsibility and social loafing; motivation and Herzberg's motivators and hygiene factors; peer pressure, conformity, norms and culture; teamwork; leadership versus management; just culture and non-punitive reporting; shift handover; work logging; closed-loop communication; and keeping up to date

How to Pass the Part-66 Module 9 Exam

What You Need to Know

  • Passing score: 75%
  • Exam length: 28 questions
  • Time limit: 35 minutes
  • Exam fee: Approx. EUR 50-230 per module sitting (varies by NAA/Part-147 organisation)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

Part-66 Module 9 Study Tips from Top Performers

1Memorise all twelve Dirty Dozen factors and at least one safety net for each; the exam often gives a scenario and asks which precursor or countermeasure applies
2Be able to classify unsafe acts precisely: slip (mis-executed action), lapse (forgotten step, often after a distraction), mistake (wrong plan), and violation (deliberate deviation)
3Know the error models cold - in Reason's Swiss Cheese the holes are weaknesses in defences, and in SHELL the central Liveware (human) meets Software, Hardware, Environment and other Liveware at the interfaces
4Learn the key human-performance figures: short-term memory holds about 7 plus or minus 2 items for 15-30 seconds, noise-induced hearing loss starts around 4 kHz, and the circadian low is roughly 03:00-05:00
5Understand the inverted-U (Yerkes-Dodson) relationship: both underload (boredom, complacency) and overload (stress) degrade performance, with an optimum in between
6Remember the exam logistics under 2023/989: 28 multiple-choice questions, 35 minutes, 75% pass mark, no essay in Module 9, and no negative marking

Frequently Asked Questions

How many questions are on EASA Part-66 Module 9 and how long is the exam?

Under Commission Implementing Regulation (EU) 2023/989, Module 9 Human Factors has 28 multiple-choice questions for all categories (A, B1, B2, B3), with a time allowance of 35 minutes. The questions are three-option multiple choice.

What is the pass mark for Module 9?

The pass mark is 75%, which is the standard for every Part-66 module. There is no negative marking, so it is worth attempting every question.

Is there still an essay in Module 9?

No. The essay component was removed from Module 9 (and Module 10) in June 2024 under Regulation (EU) 2023/989, and the multiple-choice count was raised from 20 to 28. Only Module 7 (Maintenance Practices) still includes essays - two of them.

What is the 'Dirty Dozen' and why does Module 9 cover it?

The Dirty Dozen is a list of twelve common human-factors precursors to maintenance error - lack of communication, complacency, lack of knowledge, distraction, lack of teamwork, fatigue, lack of resources, pressure, lack of assertiveness, stress, lack of awareness and norms - identified by Gordon Dupont in 1993. Each has recognised safety nets that the exam expects you to know.

What is the difference between a slip, a lapse, a mistake and a violation?

A slip is a correctly planned action mis-executed; a lapse is a memory failure where an intended step is omitted; a mistake is a planning or knowledge error (the wrong plan carried out correctly); and a violation is a deliberate deviation from a rule or procedure. The first three are unintentional errors; a violation is intentional.

How long should I study for Module 9?

Module 9 is knowledge-based with no calculations, so most candidates prepare in roughly 30-50 hours over two to four weeks, focusing on the Dirty Dozen, the error models (Swiss Cheese and SHELL), error types, and the performance-affecting factors such as fatigue, stress and shiftwork.

Does the 2023/989 transition affect older courses?

Yes. Regulation (EU) 2023/989 applies from 12 June 2024 and merged several former sub-modules. Courses started under the old standard must be completed by 12 June 2026; new study should follow the 2023/989 syllabus. UK CAA has diverged after Brexit, so confirm UK-specific requirements separately.